3.10 hydrology and water quality -...

Hydrology and Water Quality

UC Davis Volume 1 2018 Long Range Development Plan EIR 3.10-1

3.10 HYDROLOGY AND WATER QUALITY

This section discusses the existing hydrological setting for the plan area, including runoff, storm drainage, and flood control. It describes regulations and policies affecting local hydrology and water quality, discusses the existing hydrologic and water quality conditions on campus, identifies impacts that may result from 2018 LRDP implementation, and recommends mitigation measures to reduce potential impacts, where appropriate. The focus of this section is hydrologic features of the campus and receiving water quality. Information and analysis relating to domestic and irrigation water supplies and the adequacy of water/wastewater infrastructure (including treatment facilities) are presented in Section 3.17, “Utilities and Service Systems.”

Public comments on the NOP included concerns regarding floodplain management, drainage plans, discharge of treated effluent, stormwater runoff, dewatering discharge, and groundwater resources. These impacts are described and addressed within this section.

3.10.1 Regulatory Setting

FEDERAL

Clean Water Act The U.S. Environmental Protection Agency (EPA) is the federal agency primarily responsible for water quality management. The Clean Water Act (CWA) is the primary federal law that governs and authorizes federally mandated water quality control activities by EPA and the states. The CWA provides for the restoration and maintenance of the physical, chemical, and biological integrity of the nation’s waters. Various elements of the CWA address water quality, as described below.

CWA Water Quality Criteria/Standards Pursuant to federal law, EPA has published water quality regulations under Title 40 of the Code of Federal Regulations (CFR). Section 303 of the CWA requires states to adopt water quality standards for all surface waters of the United States. As defined by the act, water quality standards consist of designated beneficial uses of the water body in question and criteria that protect the designated uses. Section 304(a) requires EPA to publish advisory water quality criteria that accurately reflect the latest scientific knowledge on the kind and extent of all effects on health and welfare that may be expected from the presence of pollutants in water. Where multiple uses exist, water quality standards must protect the most sensitive use. As described in the discussion of state regulations below, the State Water Resources Control Board (SWRCB) and its nine regional water quality control boards (RWQCBs) have designated authority in California to identify beneficial uses and adopt applicable water quality objectives.

CWA Section 303(d) Impaired Waters List Under Section 303(d) of the CWA, states are required to develop lists of water bodies that do not attain water quality objectives after implementation of required levels of treatment by point source dischargers (municipalities and industries). Section 303(d) requires that the state develop a total maximum daily load (TMDL) for each of the listed pollutants. The TMDL is the amount of the pollutant that the water body can receive and still comply with water quality objectives. The TMDL is also a plan to reduce loading of a specific pollutant from various sources to achieve compliance with water quality objectives. In California, implementation of TMDLs is achieved through water quality control plans, known as Basin Plans, of the State RWQCBs. See the state regulatory setting, below, for information on the Water Quality Control Plan for the Sacramento and San Joaquin River Basins (Basin Plan).


Volume 1 UC Davis 3.10-2 2018 Long Range Development Plan EIR

National Pollutant Discharge Elimination System The National Pollutant Discharge Elimination System (NPDES) permit program was established in the CWA to regulate municipal and industrial discharges to surface waters of the United States. NPDES permit regulations have been established for broad categories of discharges including point source waste discharges and nonpoint source stormwater runoff. Each NPDES permit identifies limits on allowable concentrations and mass emissions of pollutants contained in the discharge. Sections 401 and 402 of the CWA contain general requirements regarding NPDES permits.

“Nonpoint source” pollution originates over a wide area rather than from a definable point. Nonpoint source pollution often enters receiving water in the form of surface runoff and is not conveyed by way of pipelines or discrete conveyances. Two types of nonpoint source discharges are controlled by the NPDES program: discharges caused by general construction activities and the general quality of stormwater in municipal stormwater systems. The goal of the NPDES nonpoint source regulations is to improve the quality of stormwater discharged to receiving waters to the maximum extent practicable. The RWQCBs in California are responsible for implementing the NPDES permit system (see the discussion of the state regulatory setting, below).

Dredge and Fill Permits Section 404 of the CWA allows the discharge of fill material into waters of the United States, including wetlands, lakes, streams, and rivers, as permitted under approval by the U.S. Army Corps of Engineers (USACE) and EPA. To discharge dredged or fill material into waters of the United States, including wetlands, Section 404 requires projects to receive authorization from the Secretary of the Army, acting through the USACE.

Federal Antidegradation Policy The Federal Antidegradation Policy was enacted to provide protection to high-quality water resources of national importance. It directs states to develop and adopt statewide antidegradation policies that include protecting existing instream water uses and maintaining a level of water quality necessary to protect those existing uses and the water quality of high-quality waters. In the EPA Clean Water Act regulations regarding water quality standards (40 CFR Chapter 1, Section 131.12[a][3]), the criteria for requiring an antidegradation standard includes: “where high quality waters constitute an outstanding National resource, such as waters of national and state parks and wildlife refuges and waters of exceptional recreational or ecological significance, that water quality shall be maintained and protected.”

Regulated Floodplain Floodplain Management Executive Order 11988 (May 24, 1977) directs all federal agencies to evaluate potential effects of any actions it may take in the floodplain and to avoid all adverse impacts associated with modifications to floodplains. It also directs federal agencies to avoid encroachment into the 100-year floodplain, whenever there is a practicable alternative, and to restore and preserve the natural and beneficial values served by the floodplains.

The Federal Emergency Management Agency (FEMA) oversees floodplain management and runs the National Flood Insurance Program (NFIP) adopted under the National Flood Insurance Act of 1968. FEMA prepares Flood Insurance Rate Maps that delineate the regulatory floodplain to assist local governments with land use and floodplain management decisions to meet the requirements of the NFIP. In general, the NFIP mandates that new development is not to proceed within the 100-year regulatory floodplain, if the development is expected to increase flood elevation by one foot or more. Very limited development is allowed in designated 100-year floodways (i.e., flood flow channels and areas with sufficient directional flow velocity of 100-year floodwaters).



STATE

State Water Resources Control Board In California, SWRCB has broad authority over water quality control issues for the state. The SWRCB is responsible for developing statewide water quality policy and exercises the powers delegated to the state by the federal government under the CWA. Other state agencies with jurisdiction over water quality regulation in California include the California Department of Health Services (for drinking water regulations), the California Department of Pesticide Regulation, the California Department of Fish and Wildlife (formerly Department of Fish and Game), and the Office of Environmental Health and Hazard Assessment. Regional authority for planning, permitting, and enforcement is delegated to the nine regional water boards. The regional boards are required to formulate and adopt water quality control plans for all areas in the region and establish water quality objectives in the plans. The Central Valley RWQCB is responsible for the water bodies in the project vicinity.

Term 91 Curtailment Permit and license holders having Term 91 as a condition of their water right must cease surface water diversions from the Delta watershed under the permit or license when SWRCB serves notice. A Term 91 Curtailment Notice is triggered when “Supplemental Project Water” is required to meet water quality objectives in the Delta watershed, and the Delta is in what is referred to as “Balanced” condition (i.e. water quality objectives are only being met as a direct result of Supplemental Project Water releases). Supplemental Project Water refers to the net storage releases from Shasta, Folsom, and Oroville reservoir, plus water imported from the Trinity River Central Valley Project facilities.

Water Quality Control Plan for the Sacramento and San Joaquin River Basins The Basin Plan presents water quality standards and control measures for surface and ground waters of the region. The Basin Plan designates beneficial uses for water bodies and establishes water quality objectives, waste discharge prohibitions, and other implementation measures to protect those beneficial uses. The Basin Plan contains both narrative and numeric water quality objectives for the region. Ambient water quality standards are set as objectives for a body of water and effluent limits (or discharge standards) are conditions in state or federal wastewater discharge permits, such as the NPDES permits. Land uses and activities that could degrade water quality and best management practices (BMPs) that could be used to address various nonpoint sources of pollution are identified in the Basin Plan.

Beneficial Uses The Basin Plan defines and designates the existing beneficial uses for surface and groundwater in the project area. Beneficial uses for Putah Creek are identified in Table 3.10-1.

Table 3.10-1 Designated Beneficial Uses for Waterbodies in the Plan Area Beneficial Use Definition of Use

Surface Water – Putah Creek

Municipal and Domestic Supply Community, military, or individual water supply, including drinking water supply.

Agricultural Supply Farming, horticulture, or ranching activities, including irrigation, stock watering, and support of vegetation for range grazing.

Contact Recreation Recreational activities involving body contact with water where ingestion of water is reasonably possible. These include, for example, swimming, water-skiing, or fishing.

Noncontact Recreation Recreational activities involving proximity to water, but not normally involving body contact with water. These uses include picnicking, sunbathing, hiking, beachcombing, camping, boating, and others.



Table 3.10-1 Designated Beneficial Uses for Waterbodies in the Plan Area Beneficial Use Definition of Use

Wildlife Habitat Uses of waters that support wildlife habitat including preservation and enhancement of vegetation and prey species such as waterfowl.

Freshwater Habitat Uses of water that support warm (and potentially cold) water ecosystems including, but not limited to, preservation and enhancement of aquatic habitats, vegetation, fish, and wildlife, including invertebrates.

Warmwater Spawning, Reproduction, and Development

Uses of water that support high quality aquatic habitat necessary for reproduction and early development of fish and wildlife.

Groundwater – All Groundwaters of the Central Valley Region

Municipal and Domestic Supply Community, military, or individual water supply, including drinking water supply.

Agriculture Supply Farming, horticulture, or ranching activities, including irrigation, stock watering, and support of vegetation for range grazing.

Industrial Service Supply Uses of water for industrial activities that do not depend primarily on water quality, including mining, cooling water supply, hydraulic conveyance, gravel washing, fire protection, or oil well repressurization.

Industrial Process Supply Uses of water for industrial activities that depend primarily on water quality. Source: Central Valley RWQCB 2016

Porter-Cologne Water Quality Control Act The Porter-Cologne Water Quality Control Act of 1969 (Porter-Cologne Act) is California’s statutory authority for the protection of water quality. The act sets forth the obligations of the SWRCB and RWQCBs under the CWA to adopt and periodically update water quality control plans, or basin plans. Basin plans are plans in which beneficial uses, water quality objectives, and implementation programs are established for each of the nine regions in California. The Porter-Cologne Act also requires waste dischargers to notify the RWQCBs of such activities by filing Reports of Waste Discharge and authorizes the SWRCB and RWQCBs to issue and enforce waste discharge requirements, NPDES permits, Section 401 water quality certifications, or other approvals.

NPDES Permits The SWRCB and RWQCBs, through powers granted by the federal CWA, require specific permits for a variety of activities that have potential to discharge pollutants to waters of the state and adversely affect water quality. To receive an NPDES permit a Notice of Intent (NOI) to discharge must be submitted to the RWQCB and design and operational BMPs must be implemented to reduce the level of contaminated runoff. BMPs can include the development and implementation of regulatory measures (local authority of drainage facility design) various practices, including educational measures (workshops informing public of what impacts result when household chemicals are dumped into storm drains), regulatory measures (local authority of drainage facility design), public policy measures (label storm drain inlets as to impacts of dumping on receiving waters), and structural measures (filter strips, grass swales, and retention basins). All NPDES permits also have inspection, monitoring, and reporting requirements.

General Permit for Storm Water Discharges Associated with Construction Activity The SWRCB adopted the statewide NPDES General Permit for Storm Water Discharges Associated with Construction Activity (General Construction Permit) in August 1999. The state requires that projects disturbing more than one acre of land during construction file a NOI with the RWQCB to be covered under this permit. Construction activities subject to the General Construction Permit include clearing, grading, stockpiling, and excavation. Dischargers are required to eliminate or reduce non-



stormwater discharges to storm sewer systems and other waters. A stormwater pollution prevention plan (SWPPP) must be developed and implemented for each site covered by the permit. The SWPPP must include BMPs designed to prevent construction pollutants from contacting stormwater and keep products of erosion from moving off-site into receiving waters throughout the construction and life of the project; the BMPs must address source control and, if necessary, pollutant control.

General Permit for Storm Water Discharges from Small Municipal Separate Storm Sewer Systems UC Davis is covered by the NPDES General Permit for Storm Water Discharges from Small Municipal Separate Storm Sewer Systems (Phase II Small MS4 Permit). The Municipal Stormwater Permitting Program regulates stormwater discharges from municipal separate storm sewer systems (MS4s). Stormwater is runoff from rain or snow melt that runs off surfaces such as rooftops, paved streets, highways or parking lots and can carry with it pollutants such as oil, pesticides, herbicides, sediment, trash, bacteria and metals. The runoff can then drain directly into local natural and man-made waterbodies. Often, the runoff drains into storm drains which eventually drain, untreated, into a waterbody.

MS4 permits are issued in two phases: Phase I, for medium and large municipalities, and Phase II for small ones. The Phase II Small MS4 General Permit provides coverage for small municipalities, and covers permittees statewide. The Phase II Small MS4 General Permit requires the discharger to develop and implement best management practices through a coordinated storm water program with the goal of reducing the discharge of pollutants to the maximum extent practicable, which is the performance standard specified in Section 402(p) of the CWA. The SWMPs specify what BMPs will be used to address certain program areas. The Phase II Small MS4 General Permit was updated in 2013 with permit language containing minimum control measures, timeline for implementation, and reporting requirements.

General Permit for Storm Water Discharges Associated with Industrial Activities The General Permit for Storm Water Discharges Associated with Industrial Activities (Industrial General Permit) was adopted by SWQCB in April 2014 and went into effect in July 2015. The Industrial General Permit regulates stormwater discharges for specified categories of industries, which are identified by their Standard Industrial Classification Code. The permit requires that discharges comply with stringent requirements for the protection of receiving waters, including the elimination of unauthorized non-stormwater discharges, implementation of SWPPPs and BMPs, monitoring and reporting, and executing response actions when discharges exceed results. UC Davis files NOIs for facilities that would be subject to the Industrial General Permit, as necessary. There are currently several industrial facilities on campus that have coverage under the Industrial General Permit.

State Nondegradation Policy In 1968, as required under the federal antidegradation policy described previously, the SWRCB adopted a nondegradation policy aimed at maintaining high quality for waters in California. The nondegradation policy states that the disposal of wastes into state waters shall be regulated to achieve the highest water quality consistent with maximum benefit to the people of the state and to promote the peace, health, safety, and welfare of the people of the state. The policy provides as follows:

a) Where the existing quality of water is better than required under existing water quality control plans, such quality would be maintained until it has been demonstrated that any change would be consistent with maximum benefit to the people of the state and would not unreasonably affect present and anticipated beneficial uses of such water.



b) Any activity which produces waste or increases the volume or concentration of waste and which discharges to existing high-quality waters would be required to meet waste discharge requirements.

Regulated Floodplain In 2007, the State of California passed a series of laws referred to as State Bill (SB) 5 directing California Department of Water Resources (DWR) to prepare flood maps for the Central Valley flood system and the State Plan of Flood Control, which includes a system of levees and flood control facilities located in the Central Valley. This legislation also set specific locations within the area affected by the 200-year flood event as the urban level of flood protection (ULOP) for the Central Valley.

SB 5 “requires all cities and counties within the Sacramento–San Joaquin Valley, as defined in California Government Code Sections 65007(h) and (j), to make findings related to a ULOP or the national FEMA standard of flood protection before: (1) entering into a development agreement for any property that is located within a flood hazard zone; (2) approving a discretionary permit or other discretionary entitlement, or a ministerial permit that would result in the construction of a new residence, for a project that is located within a flood hazard zone; or (3) approving a tentative map, or a parcel map for which a tentative map was not required, for any subdivision that is located within a flood hazard zone.”

There are five locational criteria that must all be met for a ULOP to apply:

The area must be a developed, urban area with 10,000 residents or more, or an area outside of a developed area that is planned or anticipated to have 10,000 residents or more within the next ten years.

The area must be located within the Sacramento-San Joaquin Valley. The area must be located within a flood hazard zone that is mapped as either an SFHA, of an

area of moderate hazard (identified by FEMA as the 500-year floodplain) of FEMA’s official FIRM for the NFIP.

The area must be located within an area with a potential flood depth above three feet, from sources other than localized conditions.

The area must be located within a watershed with a contributing area of more than 10 square miles.

However, as UC Davis is not a city or county within the Sacramento-San Joaquin Valley, the plan area is not covered by nor required to obtain coverage under the ULOP for the Central Valley.

UNIVERSITY OF CALIFORNIA

UC Davis Water Quality Program The water quality management program for UC Davis encompasses a wide array of water quality issues and addresses all pollutant sources present on campus, including stormwater, municipal water, construction discharges, industrial discharges, irrigated lands, drinking water, and sanitary sewer.

Stormwater management on campus is driven by a comprehensive program overseen by the Department of Environmental Health and Safety (EHS). EHS offers assistance and tools to prevent illicit discharges, control construction and post-construction stormwater management, and ensure programs for stormwater control are effectively achieving objectives and standards.



The water quality program regulates stormwater from municipal discharges through the MS4 permit system, described above, and regulates construction through both the MS4 permit and the General Construction Permit. EHS staff are available to provide assistance to developers. The program also supplies developers with guidance material, including SWPPP checklists and inspection forms.

UC Davis Campus Standards and Design Guide Section 01.57.23 Stormwater Pollution Prevention of the UC Davis Campus Standards and Design Guide provides regulations and standards for the protection of receiving water from contamination by stormwater discharges related to construction. The Campus Standards and Design Guide articulates the requirements of applicable laws relating to the discharge of stormwater to assist developers and contractors in executing their projects.

UC Davis Stormwater Management Plan The Phase II Small MS4 Permit requires that jurisdictions covered by the permit to comply with best management practices (BMPs) to achieve compliance with minimum control measures (Education and Outreach, Public Involvement and Participation, Illicit Discharge Detection and Elimination, Construction Site Storm Water Runoff Control, Pollution Prevention/Good Housekeeping, and Post-Construction Stormwater Management. UC Davis has a comprehensive stormwater management program, which is continuously updated to meet the MS4 permit requirements. The purpose of UC Davis’s storm water management program is to identify pollutant sources affecting stormwater quality and quantity, provide BMPs to reduce the discharge of these pollutants to receiving waters, establish measurable goals for stormwater BMPs, and focus the stormwater pollution program on prevention, rather than remediation.

UC Sustainable Practices Policy The University of California has a system-wide policy regarding sustainability practices and performance goals and targets. The policy covers the following nine areas of operational sustainability:

Green Building Design, Clean Energy, Climate Protection, Sustainable Transportation, Sustainable Building Operations, Recycling and Waste Management (to be renamed Zero Waste in the 2018 issuance), Environmentally Preferable Purchasing, Sustainable Foodservices, and Sustainable Water Systems.

The most relevant of the many policy targets to this section are the goals set in the Green Building, and Sustainable Water Systems sections. The UC Sustainable Practices Policy is frequently updated. The most recent changes were adopted in September 2017, and are expected to be formally issued by summer 2018. No changes were made to Water as part of the most recent update.

The Green Building section calls for the following goals and practices:

Design, construct, and commission all new building projects, other than acute care facilities, to outperform the CBC energy-efficiency standards by at least 20 percent or meet whole-building energy performance targets listed in Section V.A.3; and strive to design, construct, and

http://policy.ucop.edu/doc/3100155/SustainablePractices



commission buildings that outperform CBC energy efficiency standards by 30 percent or more, or meet the stretch whole-building energy efficiency performance targets.

Achieve a USGBC LEED “Silver” certification at a minimum for all new buildings, and strive for “Gold” or higher.

Meet the prerequisites for Laboratories for the 21st Century Environmental Performance Criteria. Achieve at least two points within the available credits in LEED-BD+C’s Water Efficiency category

for all new buildings.

The Sustainable Water Systems section calls for the following goals and practices:

Reduce growth-adjusted potable water consumption 20 percent by 2020 and 36 percent by 2025, when compared to a three-year average baseline of FY 2005-06, FY 2006-07, and FY 2007-08.

Develop and maintain a Water Action Plan that identifies long-term strategies for achieving sustainable water systems, including quantification of turf areas.

Identify existing single-pass cooling systems and constant-flow lab equipment, and develop a plan for replacement and avoid once-through or single-pass cooling systems for soft-plumbed systems.

For the purposes of compliance with the policy, the campus accounts for all potable water used as subject to the growth-adjusted goals.

Even though the campus’ irrigation water is not treated to be potable, the campus tracks and reports use of this water separately from the potable system with the intent of embracing the spirit of the policy, which is intended to address water used to irrigate the campus landscape.

Meeting energy efficiency goals can result in some water savings; on campus this pertains to the heating and cooling needed in buildings served by the campus district steam heating and chilled water loops. A conversion from steam to hot water heating infrastructure (discussed in Section 3.6, “Energy,” and Section 3.17, “Utilities and Service Systems,” sections) could result lower water use for district heating as well.

UC Davis Office of Safety Services UC Davis implements several programs that pertain to emergency preparedness, including those associated with potential flooding. The UC Davis oversees several emergency notification systems, including WarnMe, which provides immediate information regarding emergencies and other urgent situations that may affect the on-campus population; Crisis Manager, which provides UC Davis emergency response guides on mobile devices; and the campus webpage. In addition, the Office of Safety Services oversees the preparation of Emergency Action Plans, which identify procedures, such as evacuations, to be implemented in the event of an emergency.

LOCAL As noted in Section 3.0.2, “University of California Autonomy,” UC Davis, a constitutionally created State entity, is not subject to municipal regulations of surrounding local governments for uses on property owned or controlled by UC Davis that are in furtherance of the university’s education purposes. However, UC Davis may consider, for coordination purposes, aspects of local plans and policies for the communities surrounding the campus when it is appropriate and feasible, but it is not bound by those plans and policies in its planning efforts. With respect to Hydrology and Water Quality, there are no local plans or policies addressing energy that pertain to the 2018 LRDP.



3.10.2 Environmental Setting

SURFACE WATER HYDROLOGY The UC Davis campus is in the southwestern end of the Sacramento Valley, approximately 30 miles north of the confluence of the San Joaquin and Sacramento Rivers. The Sacramento and San Joaquin valleys make up the Great Valley geomorphic province of California, bounded by the Sierra Nevada to the east and the Coast Range to the west. The two rivers join in the Sacramento-San Joaquin Delta, a massive complex of wetlands, marshes, and channels, and enter the Pacific Ocean at the San Francisco Bay. The historic channel of the North Fork of Putah Creek flows along the southern border of the campus.

Sacramento River Watershed The Sacramento River is the largest river and watershed system in California and the second largest (by discharge) river in the United States. Its watershed covers 27,000 square miles and carries 31 percent of the state’s total surface water runoff. Primary tributaries include the Pit, Feather, and American Rivers (Sacramento River Watershed Program [SRWP] 2015). The mouth of the Sacramento River is at Suisun Bay near Antioch where it combines with the San Joaquin River.

Putah Creek Watershed Putah Creek originates from springs in the Mayacama Mountains of the Coast Range. The stream flows eastward, eventually entering Lake Berryessa. Putah Creek exits this lake through the Monticello Dam, becoming the border between Yolo and Solano Counties, ultimately flowing into the Yolo Bypass (a man-made portion of the Sacramento floodplain). Putah Creek receives tertiary treated effluent from the UC Davis wastewater treatment plant (WWTP) located approximately 0.5 mile south of the plan area. Putah Creek is currently listed on the Section 303(d) list for boron and mercury. The expected TMDL completion dates for these constituents are 2021 and 2017, respectively.

Putah Creek forks approximately 1.5 miles west of the UC Davis campus. The North Fork is the original stream channel. It historically flowed northeast toward the City of Davis, through the campus, and dissipated in a series of canals and ditches between Davis and the Yolo Bypass. The South Fork was constructed in the 1870s to protect the city of Davis from flooding (UC Davis 2010). In 1948, a USACE levee project at the mouth of the North Fork eliminated flows from the North Fork (Jones 2006). The Putah Creek channel contains the UC Davis Arboretum Waterway, which was constructed in 1969. During the dry-season, the primary source of water in the Arboretum Waterway is tertiary-treated effluent from the UC Davis wastewater treatment plant. The Waterway also functions as a stormwater detention basin for the central campus. While the original North Fork flowed east, years of dredging and grading have altered the stream topography so that the Arboretum Waterway now flows to the west (Jones 2006). The Arboretum Waterway serves as the stormwater detention basin for the central campus. When the Waterway fills, excess water is pumped out and discharged to the South Fork of Putah Creek.

The North Fork Cutoff and the Arboretum Waterway on campus follow the historic channel of Putah Creek but no longer have natural flow. The North Fork Cutoff is the former stream channel on the west campus, which is currently occupied by sheep and cattle programs in the Department of Animal Science. The North Fork Cutoff receives water from discharge from the USDA Aquatic Weed Control Laboratory, J. Amorocho Hydraulics Laboratory, and the Center for Aquatic Biology operations. The discharge is permitted under Waste Discharge Requirements (WDR) Order R5-2016-0099. The quantity and quality of flows in Putah Creek are highly variable and depend on releases from Lake



Berryessa, precipitation, stormwater runoff, and treated effluent discharge. The campus’ tertiary WWTP is the largest discharger of treated effluent to Putah Creek.

The natural flow pattern of Putah Creek has been altered by water storage in Lake Berryessa and irrigation demands. Flows from Monticello Dam (Lake Berryessa) are high in summer and low in winter in all but the wettest years (SRWP 2015). Before 2000, stream flows near Davis were very low during the summer and fall (0 to 60 cubic feet per second). The Putah Creek water accord (completed in May 2000) brought an end to a decade long dispute over water rights and stream flow requirements for fish and other natural resources and established permanent surface flows to the western boundary of the Yolo Bypass (SRWP 2015).

Historic prospecting, natural weathering, and venting from geothermal springs have created high levels of mercury and boron within Putah Creek (SRWP 2015). Consequently, the section of Putah Creek from Solano to the Putah Creek Sinks (Yolo Bypass) is listed as an Impaired Water by the EPA because of high levels of these elements.

Jurisdictional Water of the United States The main stem of Putah Creek, which is located approximately one mile south of the plan area, is a “water of the United States;” as such, any fill in the creek would be required to procure a permit under the jurisdiction of USACE. Waters of the United States generally include navigable waters (waters used for transport or commerce) and their tributaries, including wetlands with a clear connection to these waters, and all impoundments of these waters. USACE distinguishes between wetland and non-wetland waters (commonly referred to as “other waters”). Wetlands are defined as areas that are inundated or saturated by surface or groundwater for a sufficient duration to support a prevalence of vegetation adapted for life in saturated soil conditions (Title 33 CFR Section 328.3[b]). The Arboretum Waterway is a stormwater detention basin that is not continuously connected to an interstate navigable water, and is therefore excluded from the definition of a “water of the United States.”

Stormwater All campus stormwater eventually drains via campus stormwater infrastructure to Putah Creek (Exhibit 3.10-1). The central campus drainage system intercepts and collects runoff and diverts it via underground pipes to the Arboretum Waterway. During large storm events, flows increase in the Arboretum Waterway and overtop the weir at the west end, where it is captured in a pump pond on the northwest side of the weir. Additionally, stormwater from a portion of west campus (all of West Village) also drains and collects in the pump pond. From the pump pond, water is pumped through an underground storm drain and discharges to the South Fork of Putah Creek. Developed areas on the west and south campuses also include stormwater conveyance systems that drain into Putah Creek.

Most lands in the west and south campuses and at Russell Ranch are used as teaching and research fields and are not drained by stormwater drainage infrastructure. Irrigation practices on campus teaching and research fields typically do not generate stormwater runoff; however, large storm events can produce shallow overland flows that collect in temporary ponds in places such as at the edge of roads and fields.

As described above, stormwater management on campus is driven by a comprehensive program overseen by EHS. EHS offers assistance and tools to prevent illicit discharges, control construction and post-construction stormwater management, and ensure programs for stormwater control are effectively achieving objectives and standards.



Exhibit 3.10-1: Stormwater Drainage in and around UC Davis



Water Supply Section 3.17, “Utilities and Service Systems,” provides a detailed description of both domestic (potable) and utility (irrigation) water supply infrastructure and supplies. Water sources for campus comprise a combination of the resources described here, including both surface water and groundwater supplies. Treated wastewater is discharged from the UC Davis wastewater treatment plant to Putah Creek and the Arboretum Waterway; effluent discharges to the North Fork Cutoff on the west campus and the Arboretum Waterway on the central campus.

Davis Woodland Water Supply Project UC Davis is a project partner in a regional water supply project with the cities of Davis and Woodland called the Davis-Woodland Water Supply Project (DWWSP). The purpose of this project is to provide additional/redundant water supplies for the cities of Davis and Woodland, and UC Davis to address localized issues associated with providing water, including aging water systems, more stringent water quality regulations, and increasing water demands. The Woodland-Davis Clean Water Agency (WDCWA) owns and operates the project, with assistance from Reclamation District 2035 with respect to the point of intake at the Sacramento River. The surface water treatment plant was completed for the project in 2016 and provides up to 30 million gallons per day (mgd) of water. WDCWA is under contract to supply, through the project, up to 1.8 mgd of treated surface water to UC Davis.

Monticello Dam The Monticello Dam on Lake Berryessa is located approximately 25 miles from the city of Davis. The dam is a 270-foot-high, thin-arch, concrete structure which impounds a maximum of 1,602,300 acre-feet of water (Yolo County 2012). Uncontrolled water released into Putah Creek could occur either from a major or partial dam failure or from a landslide into Lake Berryessa which could cause overtopping of the dam. Seismic evaluation of Monticello Dam indicates that it could withstand a magnitude 6.5 earthquake with the epicenter located 0.5 mile from the dam (Yolo County 2012). The size and topography of the lake relative to the size of a potential landslide makes the possibility of dam overtopping unlikely, however any landslide that would place debris in the outlet works or spillway of the dam could be a threat (Yolo County 2012). In the event of a dam failure, the city of Davis would have approximately 2 hours and 45 minutes to evacuate before being reached by floodwaters. Because the dam is located in a narrow canyon with the bulk of the water stored in the lake upstream, failure of the dam would release water at a constant rate for many hours. Although most areas would see floodwaters less than 2 meters deep, the flooding would last for more than 24 hours (Ward 2014).

Floodplain On campus, the South Fork of Putah Creek, the North Fork Cutoff, and the Arboretum Waterway channels are designated as Federal Emergency Management Agency 100-year floodplain areas (as shown on Exhibit 3.10-2). In addition, a portion of Russell Ranch along County Road 31 and a portion of the west campus along County Road 98 are also subject to flooding during a 100-year storm event.

GROUNDWATER HYDROLOGY The plan area overlays the Yolo Subbasin, which is located within the broader Sacramento Valley Groundwater Basin. Regionally, the Sacramento Valley is a large, north-south trending basin filled with deep marine sediments overlain by shallow freshwater sediments that were eroded from the adjacent ranges to the west, north, and east.



Exhibit 3.10-2: Designated 100-Year Flood Zones



Locally, the campus is underlain by sand and gravel alluvial deposits that are host to deep and shallow/intermediate depth aquifers. The deep aquifer occupies sand and gravel deposits at depths ranging between 700 and 2,000 feet below ground surface (bgs). It is surmised that much of the deep aquifer is hosted by the Tehama Formation, which ranges in thickness from roughly 1,500 to 2,500 feet (DWR 2004). Water from the deep aquifer is of higher quality than water in the shallow and intermediate aquifers, and is used for domestic, drinking water, and fire water supply on campus. Six campus wells supply the domestic water supply from depths that range from 1,360 to 1,470 feet bgs (UC Davis 2018), and water drawn from these wells is monitored, and reports are prepared on a monthly and annual basis to demonstrate that the water supplied complies with state and federal drinking water standards.

Despite the campus’ significant growth in recent decades, the campus’ deep aquifer demands have not significantly increased since the late 1960s, a trend that reflects the success of the campus’ water conservation efforts. With implementation of the DWWSP, which provides for the use of surface water supplies, groundwater demands have been further reduced.

Freshwater is plentiful in the upper layers of coarse-textured, buried river and stream deposits within the Yolo Subbasin (DWR 2004). Shallow/intermediate depth sand and gravel aquifers underlie the campus at depths from 150 to 800 feet below ground surface and have historically supplied the campus utility water system, main campus agricultural water needs, and campus and tenant farmer irrigation needs at Russell Ranch. Water levels in the shallow/intermediate aquifer vary seasonally and strongly correlate to precipitation, indicating that surface water is a significant source of recharge.

The deep aquifer is characterized by water quality that is distinct from the quality of water in the intermediate-depth aquifer. Water drawn from wells extending into the deep aquifer is softer, less saline, and older than water observed from intermediate-depth wells. Water quality is the chief distinguishing characteristic between the deep aquifer the intermediate aquifer, and marks the transition between the two. The transition from “intermediate” to “deep” water is demarcated at approximately 700 feet below ground surface in the Davis area. Characteristics of the water at the center of the deep aquifer, approximately 900 to 1,300 feet below ground surface, suggest that it is the oldest water, with slow natural recharge and low hydraulic conductivity (City of Davis 2006).

Water quality in the deep aquifer suggests that historically, natural recharge occurred from surface water sources to the west. However, recent pumping activity in the deep wells could accelerate vertical recharge, as water from shallower sources migrates downwards. It has also been suggested that because of the presence of brackish water in the Delta, overdrafting of groundwater resources could lead to salt water intrusion in the deep aquifer, though none has been observed to date (Yolo County 2009). Isotopic characteristics in the shallow aquifer show higher concentrations of sodium (DWR 2004), while in the deep aquifer calcium and magnesium dominate because of longer contact periods with clays (City of Davis 2006).

Groundwater levels in the Davis area are impacted by periods of drought, which often result in increased groundwater pumping, but generally recover quickly during wet years. Pumping depressions in the vicinity of Davis, Woodland, and the Dunnigan/Zamora areas indicate a long-term trend of declining water levels in these areas (DWR 2004).

In the east Yolo Subbasin, beneath the city of Davis and UC Davis, average concentration of arsenic in the Tehama Formation are 0.04 mg/L, which exceeds the EPA maximum contaminant level of 0.01 mg/L (Yolo County 2009).



3.10.3 Environmental Impacts and Mitigation Measures

SIGNIFICANCE CRITERIA Based on Appendix G of the State CEQA Guidelines, the 2018 LRDP would result in a potentially significant impact on hydrology and water quality if it would:

violate any water quality standards or waste discharge requirements; substantially deplete groundwater supplies or interfere substantially with groundwater recharge

such that there would be a net deficit in aquifer volume or a lowering of the local groundwater table level (e.g., the production rate of preexisting nearby wells would drop to a level that would not support existing land uses or planned uses for which permits have been granted);

substantially alter the existing drainage pattern of the site or area, including through the alteration of the course of a stream or river, in a manner that would result in substantial erosion or siltation on- or off-site;

substantially alter the existing drainage pattern of the site or area, including through the alteration of the course of a stream or river, or substantially increase the rate or amount of surface runoff in a manner that would result in flooding on- or off-site;

create or contribute runoff water which would exceed the capacity of existing or planned stormwater drainage systems or provide substantial additional sources of polluted runoff;

otherwise substantially degrade water quality; place housing within a 100-year flood hazard area as mapped on a federal Flood Hazard

Boundary or Flood Insurance Rate Map or other flood hazard delineation map; place within a 100-year flood hazard area structures that would impede or redirect flood flows; expose people or structures to significant risk of loss, injury or death involving flooding, including

flooding as a result of the failure of a levee or dam; or result in inundation by seiche, tsunami or mudflow.

ANALYSIS METHODOLOGY Evaluation of potential hydrologic and water quality impacts is based on a review of existing documents and studies that address water resources in the vicinity of the plan area. Information obtained from these sources was reviewed and summarized to describe existing conditions and to identify potential environmental effects, based on the standards of significance presented in this section. In determining the level of significance, the analysis assumes that implementation of the 2018 LRDP would comply with relevant federal, state, and local laws, ordinances, and regulations.

ISSUES NOT EVALUATED FURTHER

Inundation by Tsunami, Seiche, or Mudflow Tsunamis are large waves created by earthquakes, undersea landslides, or volcanic eruptions. Low-lying coastal areas such as tidal flats, marshes, and former bay margins that have been artificially filled are susceptible to inundation. A tsunami entering the narrow mouth of the San Francisco Bay would dissipate as the energy of the wave is allowed to spread through the wide and shallow waters of the bay and delta. The California Department of Conservation prepares tsunami inundation maps for coastal areas and all populated areas at risk to tsunami within the state based on the maximum tsunami threat for that area. No areas of Yolo County are at risk from tsunami and the portion of the plan area located in Solano County is not mapped as being at risk (California Department of



Conservation 2013); therefore, this issue is not evaluated further. Additionally, because the plan area is distant from any large water bodies that could create seiche waves and located in level topography where the risk of mudflow is minimal, these issues are also dismissed from further evaluation.

IMPACTS AND MITIGATION MEASURES

Impact 3.10-1: Construction-related water quality impacts. Construction activities associated with implementation of the UC Davis 2018 LRDP would expose bare soil to rainfall and stormwater runoff, which could accelerate erosion and result in sedimentation of stormwater and, eventually, waterbodies. The plan would be required to comply with the General Construction Permit and Phase II Small MS4 Permit, and their attendant stormwater protections. In addition, UC Davis provides a comprehensive stormwater program through UC Davis EHS for development projects. This program exists to ensure compliance with applicable laws and implementation of BMPs on the ground during construction. Consequently, implementation of the 2018 LRDP would not be expected to contribute substantial loads of sediment or other pollutants to stormwater or waterbodies and would result in a less-than-significant impact.

Development under the 2018 LRDP would result in extensive disturbance during construction. Removal of vegetation, excavation, grading, and stockpiling of soils for new housing, building foundations, roads and driveways, and utility trenching would create soil disturbance that could accelerate erosion, especially during storm events. In addition to erosion and sedimentation, construction materials would be brought on site and would require containment from stormwater. While most areas of development would not be connected to surface water, storm events could generate enough runoff that stormwater from construction sites could be carried into the Arboretum Waterway or Putah Creek, and eventually on to the Yolo Bypass. This could result in impairment of receiving water beneficial uses identified for these waterways.

During construction, materials such as aggregate-base rock for roadway and parking area subgrade, sand bedding and backfill for utility lines, and crushed rock for building foundations would be brought to development areas. These materials could become exposed to stormwater and potentially result in contamination of surface water. If areas of shallow groundwater are identified or encountered during construction, they could also potentially be released to groundwater. Additionally, construction equipment may contain toxic or hazardous substances, including fuels, lubricants, oil, grease, and paint. These materials could also become exposed to stormwater runoff or to groundwater if they are not properly contained. Multiple small incidents of contamination, or larger single releases (e.g., fuel spill) could result in adverse effects on surface and groundwater quality.

While the threat of stormwater contamination during construction activities can pose a serious risk to receiving waterbodies, there are multiple layers of regulatory protections that developers must abide by when executing construction activities on campus. These include compliance with the General Construction Permit, Phase II Small MS4 Permit, and compliance with General Permit and Campus Design Guide Specification 01 57 23A, which articulates how the General Construction Permit and Small MS4 Permit are implemented. These protections are described below.

For development under the 2018 LRDP that would disturb one or more acres of land, the contractor would be required to obtain coverage under the General Construction Permit prior to construction. To comply with the General Construction Permit, a SWPPP would be prepared detailing measures to control soil erosion and waste discharges from project construction areas. The UC Davis EHS stormwater program provides a SWPPP checklist for contractors to follow to ensure that their plan meets campus and regulatory requirements. All contractors conducting construction-related work



would be required to implement the SWPPP to control soil erosion and waste discharges. The general contractor(s) and/or subcontractor(s) conducting the work would be responsible for implementing all BMPs detailed in the SWPPP. The UC Davis EHS stormwater program also implements an inspection program for construction sites and prepares written reports to ensure compliance.

The SWPPP would identify the grading and erosion-control BMPs and specifications necessary to minimize or avoid water-quality impacts to the extent practicable. Standard erosion control measures (including management and structural controls) would be required to be implemented for all construction activities that expose soil. Fill and grading materials brought in from off-site would be clean, chemically inert, and handled with appropriate containment to prevent contamination of stormwater. Grading operations would be required to eliminate direct routes for conveying potentially contaminated runoff to the Arboretum Waterway or Putah Creek. Erosion control barriers such as silt fences and mulching material would be installed. The SWPPP would contain specific measures for stabilizing soils before the onset of the winter rainfall season. Implementation of these standard erosion-control measures would reduce the potential for soil erosion and sedimentation of stormwater runoff during construction.

In the unlikely event that dewatering for an individual site is required, the SWPPP would include a dewatering plan, which would establish measures to treat groundwater pumped from the site prior to release, and to prevent/minimize sediment and contaminant releases into groundwater during excavation, as well as methods to clean up releases if they occur. Measures to prevent/minimize releases of sediment and contaminants into groundwater during excavation and methods of cleaning up releases may include using temporary berms or dikes to isolate construction activities; using vacuum trucks to capture contaminant releases; and maintaining absorbent pads and other containment and cleanup materials on-site to allow an immediate response to contaminant releases if they occur.

The UC Davis campus is also regulated by the MS4 permit program and receives coverage under the Phase II Small MS4 Permit. The MS4 permit program requires specific measures for construction site runoff control for all development through an enforceable stormwater runoff control ordinance. To this end, UC Davis has prepared a Design and Construction Management guide, containing campus standards for stormwater pollution prevention. The guide requires that construction projects creating land disturbance of less than one acre complete an Erosion Control Plan and comply with minimum BMPs.

As previously discussed, UC Davis provides a unified construction stormwater protection program through campus EHS. EHS reviews SWPPPs and all permit registration documents for compliance with the General Permit and Campus Design Guide Specification 01 57 23A. This regulatory framework provides adequate protection from stormwater contamination, resulting in less-than-significant construction-related water quality impacts.

Mitigation Measures No mitigation measures are necessary.



Impact 3.10-2: Long-term water quality impacts. New impervious surfaces from development of the 2018 LRDP would result in new sources of stormwater runoff and contamination, as well as an increased risk of erosion and sedimentation. However, the campus is covered under the Phase II Small MS4 Permit, which requires management of long-term stormwater discharges and implementation of pollution protection measures. These management practices are enforced under the campus stormwater management program and ensure long-term protection related to stormwater pollution. Permit coverage and compliance with the stormwater management program would result in less-than-significant impacts associated with long-term water quality impacts.

Increased rates of surface water runoff associated with new impervious surfaces could promote increased erosion and sedimentation or other stormwater contamination and negatively impact surface water and groundwater quality. The main sources of long-term stormwater pollution from development are roads, automobiles, landscaping, industrial activity, spills, and illegal dumping. Developed areas can produce stormwater runoff that contains oil, grease, and heavy metals, while stormwater runoff from agricultural areas can carry sediment and agricultural chemicals into drainage pathways, and ultimately to adjacent waterbodies. The network of stormwater drainage diversion structures on campus collects overland stormwater flows and diverts them to stormwater mains for outfall into Putah Creek, the receiving waterbody for all stormwater drainage on campus (Exhibit 3.10-1).

Maintenance of the campus’ landscaped areas requires some application of fertilizers (applied to lawn areas), insecticides, and herbicides (which are primarily applied along roadsides for fire protection). Applications of landscape and building maintenance chemicals on campus grounds are done in compliance with manufacturer label instructions and would continue to be applied in this manner with implementation of the 2018 LRDP.

The potential for development sites to generate polluted runoff would be minimized through mandatory compliance with the UC Davis stormwater program. As previously discussed, the campus operates under the MS4 Phase II General Stormwater Permit, which requires the UC Davis to enforce a post-construction stormwater management program for new development meeting certain criteria. For projects that create or replace less than 2,500 square feet of impervious surface, no stormwater management protections are required. However, projects that will replace or create between 2,500 and 5,000 square feet are required to implement site design measures, and projects over 5,000 square feet must implement LID design standards. Site design measures are intended to reduce project runoff, while LID design standards are a comprehensive approach to land development that manages stormwater by preserving or re-creating landscape features to treat stormwater as a conservation resource. Site design features might include:

stream setbacks and buffers, soil quality improvement and maintenance, tree planting and preservation, rooftop and impervious area disconnectivity, permeable pavement, green roofs, vegetated swales, and rain barrels and cisterns.



LID design standards are substantially more protective because they are specifically engineered to address stormwater runoff. Examples include:

a combination of site design measures, above; source control measures; numeric sizing criteria for stormwater retention and/or treatment; stormwater treatment projects (including bioretention); and hydromodification management measures.

Source control measures would be designed consistently with the California Stormwater Quality Association Stormwater BMP Handbook for New Development/Redevelopment. UC Davis also engages an operations and maintenance program that specifies routine maintenance for site design measures and LID designs that have been implemented for new development projects. Compliance with the UC Davis stormwater management program and implementation of the above stormwater protection measures would result in less-than-significant impacts on long-term water quality for campus receiving waters.


Impact 3.10-3: Violate water quality standards – waste discharge. Expansion of the campus population and campus facilities under the 2018 LRDP would result in an increase in the amount of wastewater generated. It is expected that the types of chemical constituents in wastewater would remain approximately the same with implementation of the 2018 LRDP. By continuing to adhere to the provisions of NPDES permit CA0077895, it is expected that the wastewater treatment plant would continue to comply with WDRs, and therefore impacts associated with water quality standards would be less than significant.

Development under the UC Davis 2018 LRDP would increase the quantity of wastewater generated on campus by increasing the both the campus population and the number of campus buildings and facilities. The quantity of wastewater currently treated at the UC Davis wastewater treatment plant is approximately 1,800 acre-feet per year. Based on an extrapolate per-service-population demand factor of 0.38 acre-feet per year, the quantity of water treated at the wastewater treatment plant under the 2018 LRDP forecast academic year (2030–2031) could increase to approximately 2,200 acre-feet per year (UC Davis 2018). Assessment of the capacity of the wastewater treatment plant to handles these flows is provided in Section 3.17, “Utilities and Service Systems.”

Development would include an expansion of the same land use types and activities that are currently allowed on campus and would not result in land uses with an increased likelihood of contributing high concentrations of contaminants to wastewater. The campus wastewater treatment plant (refer to Section 3.17, “Utilities and Service Systems,” for additional information) provides advanced tertiary treatment for campus wastewater—a level of treatment that allows for recycled water use--which is discharged to Putah Creek and the Arboretum Waterway under NPDES Permit CA0077895 (WDR Order R5-2014-0152). Operation of the existing UC Davis wastewater treatment plant began in March 2000, and since then, discharge from the facility has largely complied with applicable WDRs in the NPDES permit. UC Davis has implemented a pretreatment program and modified wastewater treatment plant operations to enhance the efficiency of treatment at the wastewater treatment plant



and achieve compliance with permit conditions. The NPDES permit contains robust operational and maintenance specifications, as well as monitoring, reporting, and analysis requirements to ensure that treated effluent complies with the WDRs. The NPDES permit identifies special studies and technical reports related to Basin Plan objectives to reduce biological toxicity in effluent discharges, as well as BMPs to reduce salinity in the wastewater treatment plant effluent discharges. Close monitoring and analysis of effluent trends enables early detection of potential issues with treating wastewater and the opportunity to adaptively manage flows and operations.

The pretreatment program mentioned above communicates safe sewer disposal guidelines to existing and new staff to inform them of what can and cannot be discharged to the sanitary sewer, and to monitor for inappropriate discharges to the sanitary sewer system. The guidelines were established to protect worker health and safety, prevent upset conditions at the wastewater treatment plant, protect against permit violations, and prevent adverse environmental impacts.

An increase in the student population at campus during the summer, as projected under the 2018 LRDP, would result in an increase in influent to be treated at the wastewater treatment plant, therefore also increasing the effluent discharged during summer. Because summer flows in Putah Creek are very low and therefore highly responsive to campus discharges, an increase in treated discharges to Putah Creek and the Arboretum Waterway would contribute to improved water quality during summer. Compliant, treated wastewater discharges would comingle with untreated campus runoff, producing a beneficial effect on water quality in these receiving waters.

The campus does not anticipate compliance challenges in meeting the WDRs for the wastewater treatment plant. It is expected that with current and future control programs and possible operational changes, increased influent going to the wastewater treatment plant could be handled and discharges would comply with the NPDES WDR requirements and would therefore not degrade receiving water quality or compromise beneficial uses in Putah Creek. Campus would continue to monitor effluent discharge in compliance with the applicable WDRs, and if the effluent limits are approached or exceeded, the campus would modify its pretreatment program and wastewater treatment plant operation as appropriate. The measures for monitoring and provisions for compliance contained within the NPDES permit are robust and would result in a less-than-significant impact with respect to water quality standards.


Impact 3.10-4: Impacts to deep aquifer groundwater supply and recharge. UC Davis will continue to draw domestic water from the six campus wells in the deep aquifer, during Term 91 conditions and to supplement water from the Woodland-Davis Clean Water Agency, for campus use. However, campus use of groundwater supplies would not substantially affect the available supplies within or ability for recharge of the deep aquifer. Impacts would be less than significant.

Potable water for UC Davis is provided by a combination of surface water from the DWWSP and groundwater from the deep aquifer below campus. As discussed in Section 3.17, “Utilities and Service Systems,” UC Davis is eligible to receive a dedicated project capacity from the DWWSP of up to 1.8 mgd. When dedicated capacity is not available from the DWWSP, for example during Term 91 Conditions, UC Davis continues to draw groundwater from the deep aquifer as a domestic



source. Six campus wells provide access to the deep aquifer and produce contribution to the domestic water supply.

The DWWSP was designed for three consumers’ jurisdictions—UC Davis and the cities of Woodland and Davis—specifically to alleviate some of the problems associated with overconsumption of groundwater and to provide for conjunctive use to promote conservation, recovery, and protect the quality of groundwater supplies. While the DWWSP did not consider specific growth projections for UC Davis, the project itself was envisioned to accommodate general growth in the region. Current domestic water consumption on campus is estimated to be approximately 573 million gallons per year (UC Davis 2018), which translates to an average consumption of approximately 1.6 mgd. During normal years, when water is available from the DWWSP, this demand is met by surface water, except for peak demand days during the summer months for campus use when day demands may exceed 1.8 mgd. During dry periods and to meet peak day demands, water continues to be drawn from the six campus wells that tap the deep aquifer. Projected demand for domestic water under the 2018 LRDP build out academic year of 2030–2031 ranges between 811 and 968 million gallons per year (UC Davis 2018), which represents between a 41 and 69 percent increase in the quantity of water consumed by campus. The projected maximum consumption figure would result in approximately 2.65 mgd of domestic water consumption, a figure which could not be met by the DWWSP, even in normal water years (UC Davis 2018). Up to 0.85 mgd of groundwater would be required from the deep aquifer to meet campus water needs. Alternatively, UC Davis could construct a satellite water treatment plant that would treat Solano Project water supplies to meet drinking water standards for use in on-campus buildings. However, for the purposes of this analysis, it is conservatively assumed that the projected increase in demand would rely on groundwater from the deep aquifer. It should also be noted that this projected increase does not account for expanded implementation of campus programs related to water conservation and efficiency.

Bulletin 118 states that the Yolo Subbasin does not exhibit any significant declines in groundwater levels, with the exception of localized pumping depressions in several areas including in the vicinity of Davis (DWR 2004). Further, in an update to Bulletin 118, the Yolo Subbasin was not identified as one of several basins subject to critical conditions of overdraft (DWR 2016). Historical groundwater elevation measurements show that groundwater elevations declined through the 1950s and 1960s and then increased as a result of the implementation of the Lake Berryessa and Indian Valley Reservoir regional surface water supply projects. In addition to the groundwater elevation changes resulting from variation in land and water use practices over time, groundwater elevations have fluctuated in response to changes in precipitation (City of Davis 2016). As a result and supported by more recent available groundwater information from DWR, groundwater levels in the area are considered to be relatively stable. Groundwater levels within the UC Davis campus did not see an overall decline in elevation between 2012 and 2017, which includes the multi-year drought period of 2012 to 2016 (DWR 2018). Further, the City of Davis, which historically used groundwater supplies from the deep aquifer to satisfy its potable water demand, has primarily transitioned to using surface water supplies available through the DWWSP, thereby further reducing groundwater pumping in the Yolo Subbasin. Even prior to transitioning to surface water through the DWWSP, the City had reduced the volume of groundwater pumped from the deep aquifer by approximately 2 mgd (2,300 acre-feet per year) (City of Davis 2016). As a result, the projected demands for groundwater under the 2018 LRDP would be less than historic demands placed on the Yolo Subbasin. Combined with determinations made by DWR regarding the Yolo Subbasin, the demand for groundwater supplies within the deep aquifer under the 2018 LRDP is not anticipated to result in substantial decline of the deep aquifer, which has not been identified by DWR as being in decline. In addition, the Yolo County Flood Control District is currently implementing a groundwater monitoring program for the Yolo Subbasin with participation from UC Davis. Should future concerns regarding overdrafting of groundwater be identified, UC Davis with other agencies in the area would develop water conservation



or alternative water delivery methods, including the aforementioned Solano Project water supplies to reduce demands for groundwater. As such, impacts would be less than significant.


Impact 3.10-5: Impacts to shallow/intermediate aquifer groundwater supply and recharge. While implementation of the 2018 LRDP is not expected to increase groundwater withdrawals from the shallow/intermediate aquifer, recharge infiltration patterns could be affected by the increase in development. However, new impervious surfaces from the conversion of open space to other uses represent a small fraction of total campus lands, and lands within the Putah Creek watershed, which feeds the underlying aquifer through recharge. Therefore, the result would be a less-than-significant impact on shallow/intermediate aquifer supply and recharge.

UC Davis draws water from both the shallow/intermediate and deep aquifers to meet campus water needs. The shallow/intermediate aquifers, being of marginal water quality, supply agricultural and utility water use. Implementation of the 2018 LRDP is not projected to result in an increase in agriculture or utility water consumption as the acreage of such uses would not increase under the 2018 LRDP. Recharge to the shallow/intermediate aquifer occurs directly from campus surface water infiltration. Major sources of groundwater recharge are farm irrigation seepage, infiltration of rainwater, seepage from natural channels, and seepage from irrigation channels/canals and stormwater detention basins (including the Arboretum Waterway). Recharge could be impeded by development that increases the amount of impervious surface on campus.

The UC Davis 2018 LRDP proposes an overall increase in the amount of impervious surfaces on campus. This, together with expanded development in the surrounding areas of Davis and Woodland, could impede recharge to the shallow and intermediate aquifers underlying the area. Land Use designated as Undeveloped Open Space would, in some areas of campus, be converted to Faculty & Staff Housing and Academic & Administrative land uses. In total, just over 143 acres of undeveloped open space would be converted to alternate land uses under the plan (see Table 2-2 in Chapter 2, “Project Description”).

While there would be an increase in impervious surface coverage on campus, development and redevelopment projects would be required to implement post-construction stormwater control, which would enhance the infiltration capacity of campus lands overall. Post-construction stormwater control involves the inclusion of permanent features in the final design configuration of a site. Ostensibly, these features are included to reduce pollutants and the erosive force of stormwater flows, but they do so primarily by enhancing infiltration to ground, which has the additional benefit of providing a valuable source of groundwater recharge. The primary tool for stormwater control is LID techniques that preserve and/or recreate natural landscape features as permanent design features for a project. As described under Impact 3.10-2, examples of LID techniques that could be used in development and redevelopment projects include source control measures, stormwater treatment projects (including bioretention), and hydromodification management measures.

Additionally, conversion of open space constitutes less than three percent of UC Davis campus lands and represents a minor increase in the overall amount of impervious coverage on campus. The amount of campus land that is currently allocated to uses that involve impervious land coverage (academic and administrative buildings, residential space, and infrastructural space) composes



approximately 25 percent of campus. With implementation of the 2018 LRDP, this would increase to approximately 29 percent. This represents a small amount of the total impervious coverage in the Putah Creek watershed, which provides direct surface water recharge to groundwater. Putah Creek receives surface water from approximately 71 square miles in Lake, Napa, and Solano counties (Sacramento River Watershed Program 2015), much of which is undeveloped, mountainous terrain.

Site design measures for source control implemented at medium-sized development sites, and LID design standards implemented at large-scale development sites would enhance surface water infiltration and therefore promote groundwater recharge. Redevelopment sites in particular would benefit from long-term post-construction stormwater controls. In addition to stormwater control and enhanced groundwater infiltration, the development area under the 2018 LRDP represents only a small percentage of open space regionally, and runoff from this additional area would be detained on-site and within campus (e.g., the Arboretum Waterway) in accordance with applicable regulations such that groundwater recharge would still occur. Therefore, the incremental impact of new impervious surfaces would not be substantial on groundwater recharge. This would be a less-than-significant impact.


Impact 3.10-6: On-site and off-site flood-related impacts. New development on campus would result in an overall increase in impervious surfaces and produce changes to site-specific stormwater infrastructure. If new stormwater infrastructure is not appropriately designed to accommodate site runoff, or existing campus infrastructure cannot accommodate increased flows from new development, impacts related to local and off-site flooding would be significant.

Stormwater generated on campus during heavy precipitation events normally results in localized on-site ponding at storm drain inlets and along roadsides and does not generally result in property damage. Serious consequences are not normally realized because stormwater generated on existing development is controlled by engineered stormwater infrastructure that is sized (10-year storm event) appropriately for collection and conveyance of water. In the absence of stormwater improvements at new development sites, storm events could result in an increase in the frequency or magnitude of localized flooding, causing property and utility infrastructure damage.

The most significant change to the plan area under the 2018 LRDP that could have an impact on drainage and flooding would be the increase in impervious surfaces with implementation of the 2018 LRDP. New areas would be developed and would therefore result in an increase in new impervious surfaces, as described in Impact 3.10-5.

In addition to changes in impervious surfaces on campus, development could involve changes to stormwater infrastructure. The pattern of drainage, infrastructure connectivity, and the locations of specific features could change. Stormwater infrastructure that is not replaced or redesigned could contribute to problems associated with drainage and flooding. This would be a significant impact.

Mitigation Measure 3.10-6: Implement project-level stormwater controls. Implement Mitigation Measure 3.7-4.



Significance after Mitigation Implementation of Mitigation Measure 3.10-6 would require drainage studies of projects proposed under the 2018 LRDP and would ensure that necessary stormwater systems and/or on-site detention facilities would be engineered and constructed with appropriate sizing for anticipated storm events. This mitigation would reduce potential impacts associated with localized flooding to less-than-significant levels.

Impact 3.10-7: Placement of housing or other structures within a regulated floodplain. Portions of the plan area are located within a floodplain, however, no new student, or faculty and staff housing is proposed within the 100-year floodplain. The 2018 LRDP may involve the construction of addition academic and administrative facilities within the far western portion of west campus. Should that occur and in the event of a 100-year flood, there would be increased exposure to the risk of loss and flood damage. Therefore, the impact associated with a 100-year flood event would be potentially significant.

No new student, or faculty and staff housing is proposed within the 100-year floodplain, however implementation of the 2018 LRDP may result in development of additional academic and administrative facilities in the western portion of the west campus. The amount of new development proposed in west campus would represent a small fraction of the total acreage in the Putah Creek floodplain. While this amount of development is unlikely to affect stage heights during a 100-year flood, placement of structures within the floodplain could expose them to the risk of inundation and associated loss.

Flood zones along the Arboretum Waterway and the South Fork Putah Creek would remain designated Open Space under the 2018 LRDP. The UC Davis campus is not within a designated ULOP area, and therefore there are no regulated 200- or 500-year floodplains.

In the event of a 100-year flood, there would be increased exposure to the risk of loss and flood damage in the areas of west campus where administrative facilities would be expanded under the plan. Therefore, the impact associated with a 100-year flood event would be potentially significant.

Mitigation Measure 3.10-7: Design of new construction to minimize the risk of flooding in the event of a 100-year flood. New construction within the 100-year floodplain shall be designed to be elevated above the base flood elevation predicted under a 100-year flood event. UC Davis shall require site-specific studies to be conducted to ascertain the height to which floodwaters would be expected to rise. These studies shall inform fill and grading requirements for new development within the floodplain and any requirements/recommendations from the site-specific studies shall be incorporated into design. Where elevating projects is not possible, buildings shall be designed to wet floodproof the lowest elevation floors and utility systems.

Significance after Mitigation Mitigation Measure 3.10-7 would ensure that buildings are elevated appropriately or are floodproofed to withstand a 100-year flood event. Implementation of Mitigation Measure 3.10-7 would ensure that the impacts from risks associated with a 100-year flood event are less than significant.



Impact 3.10-8: Dam failure inundation. Although UC Davis is located within the inundation area of the Monticello Dam, such that up to two meters of water would be present in certain areas of campus for a period of approximately 24 hours, the dam structure is managed by the state and federal agencies and is capable of withstanding strong seismic shaking. As a result, the risk of inundation from a failure of the Monticello Dam is considered less than significant.

UC Davis is in the floodplain beneath Monticello Dam at Lake Berryessa. A catastrophic failure of this dam could cause flooding of up to two meters deep, and last for up to 24 hours (Ward 2014). Potential causes of dam failure include seismic failure, overtopping of dam capacity (usually because of unexpectedly heavy rainfall in the watershed), spillway blockage, failure of the dam foundation because of poor maintenance, and failure because of piping and seepage from internal cracks in the dam structure (Burns 2014). The recent seismic evaluation of the dam indicates that it can withstand a magnitude 6.5 earthquake with the epicenter located 0.5 mile from the dam (Yolo County 2012), and therefore is unlikely to be affected by seismic events.

Dam safety requires a comprehensive and long-term process of site maintenance, continuous inspection and monitoring, and implementation of periodic site improvements. The Monticello dam has such a program, managed by the U.S. Department of Interior, Bureau of Reclamation (BOR). The BOR’s dam safety program includes a four-step program that continuously monitors the status of dams. Every four years the dam is reviewed and inspected. This involves an assessment of seismic, hydrologic, and static parameters. If this review indicates any items of concern, further studies are completed to fully understand the potential area of weakness and corrective actions are taken. In addition, daily visual inspections of the dam are completed by the Solano Water District dam tender (Burns 2014).

The Yolo County Multi-Hazard Mitigation Plan (2012) places the probability of failure of any of the County’s dams at less one percent for the period of the next 100 years. In addition, and as noted above, the UC Davis Office of Safety Services implements numerous programs and oversees preparation of Emergency Action Plans for campus that provide updated information and guidance to students, faculty, and staff in the event of an emergency, including flooding as a result of dam failure. For these reasons, combined with the stability of the Monticello Dam and the ongoing BOR dam safety program, the potential for flooding due to dam failure would be minimal, potential flood risks as a result of dam failure would represent a less-than-significant impact.




This page intentionally left blank.

3.10 hydrology and water quality -...

Documents