section 4.8 hydrology and water quality 4.8.1 introduction i_04.08 hydrology.pdf · system in the...

Draft EIR September 2007 PdV Wind Energy Project 4.8-1 002147.EX09.01

Section 4.8 Hydrology and Water Quality

4.8.1 Introduction This section of the EIR addresses potential impacts of the proposed project on hydrology and water quality, describes the environmental and regulatory settings, and discusses mitigation measures to reduce impacts where applicable. The information in this section is based primarily on the biological field studies conducted and reported by Sapphos Environmental in 2006. The complete report is provided in Appendix C of this EIR. In addition, information from numerous other sources was reviewed, including the State Water Resources Control Board, the California Department of Fish and Game (CDFG), and the Federal Emergency Management Administration (FEMA). While the location of turbines and associated facilities would vary slightly between Scenario 1: Array Configuration and Scenario 2: Optimized Configuration, the overall area of disturbance to surface waters and associated riparian habitat, grading, and increase in impervious surface would be the same because the same drainages would be crossed by proposed new dirt or gravel access roads. Both would result in approximately 4% of permanent disturbance and 6% of temporary disturbance from grading, and the same number of turbines and permanent structures requiring foundations would be installed. Therefore, the discussion in this section thus applies equally to both scenarios.

4.8.2 Environmental Setting Climate

Kern County is located in the Mojave Desert Basin where the climate can be characterized as hot in the summer and cold in the winter. Average temperatures recorded in Rosamond, located approximately 15 miles to the southeast, range from a low of 29º Fahrenheit (F) in December to highs of 95º F in July and August (City Data 2006). The project site is located in the Antelope Valley area of the Mojave Desert Basin, the westernmost desert valley, where the climate is dry. Precipitation ranges from 3 inches on the floor of the Antelope Valley

County of Kern Section 4.8. Hydrology and Water Quality


to nearly 36 inches near the crest of the San Gabriel Mountains, which border the Antelope Valley (U.S. Geological Survey 2000).

Hydrology Surface Hydrology

The proposed project site is characterized as a gradually sloping plateau, sloping from the northwest to the southeast. The elevation of the proposed project is between 3,100 and 5,800 feet above mean sea level (amsl). Surface waters in the project site drain into Cottonwood Creek. The project site is within the Antelope-Fremont Valleys Hydrological Unit (18090206) and in the Willow Springs Hydrologic Area (626.30), as defined by the California Regional Water Quality Control Board, Lahontan Region (RWQCB) (Lahontan Regional Water Quality Control Board 1994). The Antelope Valley is a closed basin and is characterized by infrequent alluvial fans and dry washes that terminate in the desert. Figure 4.8-1 illustrates the regional drainage system in the project vicinity. Most of the drainages flow into the groundwater aquifer or evaporate and the remaining waters flow into Rosamond Lake. Drainages Based on a review of U.S. Geological Survey (USGS) topographic maps, aerial photos, and field studies, thirteen blue-line drainages were identified within the proposed project site. Of these drainages, Cottonwood Creek is the only named drainage; ten drainages are tributaries to Cottonwood Creek, and the remaining two drainages are along the eastern boundary of the project site. In total, approximately 24.5 miles of these blue-line features cross the project site. Cottonwood Creek is located in the southwestern corner of the project site, as shown in Figure 4.8-1. The Los Angeles Aqueduct, a channelized water feature, also crosses the southwestern portion of the project site. Unlike the other drainages, this water feature continues out of the watershed basin; however, it is self contained and travels through the project site without receiving drainage or contributing to any drainage within the project site. Each of these blue-line drainages were evaluated to determine whether they are jurisdictional waters of the U.S. and/or the state, based on the definitions of the U.S. Army Corps of Engineers (USACE) and the CDFG.

0 2.5

Miles

Figure 4.8-1

Regional Drainage SystemPdV Wind Energy ProjectKern County, California

Ecology and Environment, Inc.

Sources: 1) Sapphos Environmental, Inc., 2006; 2) enXco, ESRI, USGS, Thomas Brothers

002147.EX09.01.x(BW).ai (2007 Corp Archives CD - Vol 2) 05/21/2007

Project Site

Drainage system

Terminus ofCottonwood Creek



This evaluation for federal jurisdiction concluded that none of these drainages are likely to be considered jurisdictional waters of the U.S. by the USACE because, as described above, the project site is located within a closed basin and surface waters present do not connect to navigable waterways. The only named blue-line drainage in the project site is Cottonwood Creek, a non-navigable stream that terminates approximately 2.4 miles southeast of the proposed project site at Rosamond Lake, which has no outlet. In addition, no other activity that may be considered interstate commerce, including recreational use, industrial use, or fishing or harvest of shellfish for sale, occurs within the project site on any of these drainages or upstream or downstream of the project site. The USACE concurred with the determination that the project would not affect any area protected pursuant to Section 404 (U.S. Army Corps of Engineers 2006). An evaluation for state jurisdiction concluded that one of the drainages, Cottonwood Creek, is likely to be considered a water of the state by the CDFG pursuant to section 1603 of the California Fish and Game Code. This finding is based on the presence of a defined bed and bank and riparian vegetation within the channel (not on the adjacent banks), including, at low densities, such species as annual rabbit-foot grass (Polypogon monspeliensis) and mulefat (Baccharis salicifolia). However, no aquatic vertebrates were observed at Cottonwood Creek or any of the other drainages within the project site, and no state or federally listed species reside within the project site. Swainson’s hawk (Buteo swainsoni), a state-listed species, was observed as a migrant in the project site during field surveys, although it was determined to be a non-resident species. Plant and wildlife species occurring in the project site are discussed in detail in Section 4.4, “Biological Resources.” All of the remaining drainages were found to be either ephemeral or lacking the physical properties necessary to support surface water and riparian vegetation. These drainages can be characterized as hillslope drainage features that have formed tributary valleys throughout the project site, draining either to Cottonwood Creek or the unnamed drainage located at the terminus of Tylerhorse Canyon only during moderate rainfall events. Some of these drainages exhibit signs of periodic sheet and gully flow, as evidenced by minor slope incision and the presence of coarser soils than found in surrounding areas. However, these features are dominated by the presence of non-native grasses and show signs of human disturbances such as off-highway vehicle and grazing-related impacts. Additional information regarding drainages in the project site, including detailed maps and photos, is provided in the Biological Resources Technical Report included with this EIR as Appendix C.



The applicant has stated that final design would avoid placing turbines or buildings within any of the blue-line drainages. Cottonwood Creek and its tributaries are depicted on the constraints map (see Figure 3-4). However, the proposed dirt and gravel access road network would cross these features at 38 locations, as shown in Figure 4.8-2. Three of these crossings are on Cottonwood Creek, which is a jurisdictional water of the state; therefore, a 1602 Lake and Streambed Alteration Agreement (SAA) from the CDFG would be required to construct access roads across the creek. (As described above, none of the other drainages in the project site would be subject to the jurisdiction of the CDFG; therefore, an SAA would not be required for these crossings.) At the crossing locations, the width of Cottonwood Creek varies from 49.5 feet to 36.3 feet to 23.1 feet. Maps and photos of these crossing locations are included in the Biological Resources Technical Report provided in Appendix C. Because the proposed access roads would be 36 feet wide, approximately 0.1 acre of jurisdictional surface water would be temporarily affected. This would be reduced to less than 0.1 acre after construction because the edges of the access roads would be reduced by 20 feet, leaving only a permanent 16-foot-wide access road through the drainages. The new off-site access road from the terminus of 170th Street West to the southern boundary of the project site would include two crossings of the Los Angeles aqueduct. The applicant would install box culverts at both of these crossings. Therefore, the post-construction condition of this “water” feature would be the same as it is currently – concrete-channelized feature. Additional discussion of these crossings is provided in Section 4.15, “Transportation and Traffic.” Wetlands The National Wetland Inventory (NWI) maps identify only a very small area of wetlands in the northwest corner of the project site along the project boundary line (see Figure 4.4-3). Based on field surveys and literature reviews, no other wetlands were identified in the project site. Also as shown in Figure 4.4-3, no wind turbines or associated facilities would be located within NWI-mapped wetlands. The applicant would avoid placing turbines or other aboveground infrastructure within any of the wetlands, which are included on the constraints map (see Figure 3-1).

Figure 4.8-2

Blueline Drainage/Access Road IntersectionsPdV Wind Energy ProjectKern County, California


Sources: 1) Sapphos Environmental, Inc., 2006; 2) PowerPartners Southwest LLC, 2006

002147.EX09.01.w2(BW).ai (2007 Corp Archives CD - Vol 1) 05/21/2007

Intermittent drainage

Proposed road

Project boundary

Blueline drainage/road intersection

T9N – R15WT9N – R15W

T10N – R15WT10N – R15W

0 2,500 5,000

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0 2,500 5,0001,2501,250

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(Note:Sec. 21removed

from ProjectArea)

(Note:Sec. 21removed

from ProjectArea)



Groundwater Hydrology Groundwater Basin Boundaries The project site is underlain by the Mojave Groundwater Basin, an area that encompasses the Mojave Desert. The Mojave Groundwater Basin is subdivided into many subunits, and the project site is within the Antelope Valley groundwater sub-basin. The Antelope Valley is a 2,400-square–mile, arrow-head shaped area, bounded on the northwest by the Tehachapi Mountains and the San Gabriel mountains to the southwest (U.S. Geological Survey 2000). The Antelope Valley has an approximately 385-square-mile drainage area and an estimated 40,700 acre-feet total yearly runoff (Lahontan Regional Water Quality Control Board 2002). The Antelope Valley groundwater sub-basin is approximately 940 square miles and is separated from the northern part of Antelope Valley by faults and low-lying hills (U.S. Geological Survey 2003). The project site is located in the jurisdiction of the Lahontan RWQCB. Subsurface Geology and Groundwater The Antelope Valley groundwater sub-basin is a basin and range basin-fill aquifer, comprising alluvial and lacustrine deposits (National Atlas 2005; U.S. Geological Survey 2000). The alluvium consists of unconsolidated to moderately indurated, poorly sorted gravels, sands, silts, and clays. The older deep units within the alluvium typically are more compacted and indurated than the younger shallow units. The fine-grained lacustrine deposits consist of sands, silts, and clays that accumulated in a large lake or marsh that at times covered large parts of the study area (Allwest Geoscience 2005). The Antelope Valley groundwater sub-basin is a single, undrained, closed basin that was historically separated into an upper, principal aquifer, which is unconfined, and a lower aquifer under artesian conditions (U.S. Geological Survey 2003). The USGS 2003 Water Resources Investigation Report 03-4016 asserts that a more reasonable conceptual model of the groundwater system would divide the ground-water basin into the three aquifers, the upper aquifer extending from the water table to an altitude of about 1,950 feet above sea level; the middle aquifer extending from 1,950 to 1,550 feet above sea level; and the lower aquifer extending from 1,550 feet above sea level to the altitude at which bedrock is encountered. There is a general shallowing of the aquifers toward the mountainous areas over the entire aquifer, although there is little data from within the proposed project site to support this. Only one well several miles northeast of the project area has groundwater information, which was collected in the 1950s (U.S. Geological Survey 2005).



Natural sources of groundwater recharge include runoff from ephemeral streams from the surrounding mountainous areas and, to a lesser extent, direct infiltration of precipitation and lateral ground-water underflow from adjacent bedrock areas and basins (U.S. Geological Survey 2003). Human sources of recharge from development include irrigation return flow and infiltration of treated wastewater. Evaporation rates are high in the Antelope Valley and, prior to development, groundwater and surface water discharge was primarily due to evapotranspiration (U.S. Geological Survey 2003; County Sanitation Districts of Los Angeles County 2004). However, evapotranspiration has been replaced by groundwater pumping as the primary cause of discharge. Prior to 1972, groundwater provided more than 90% of the total water supply in the Antelope Valley. Since 1972, it has provided between 50% and 90%. The groundwater level in some parts of the Antelope Valley has declined more than 200 feet because of an increase in pumping lifts, reduced well efficiency, and land subsidence of more than 6 feet in some areas (U.S. Geological Survey 2003). Most groundwater is pumped from the Antelope Valley groundwater sub-basin, which supplies the rapidly growing cities of Lancaster and Palmdale. More than twice as much groundwater is currently extracted in Antelope Valley as the estimated mean natural recharge (U.S. Geological Survey 2005). Available data for groundwater resources indicates that domestic water sources are groundwater extracted from local wells and imported water from the Antelope Valley East Kern Water Agency. Water wells in the region derive potable water from a depth of about 200 to 300 feet. Shallower water-bearing formations are likely present. As discussed in Chapter 3, “Project Description,” the project may require the installation of a well to provide a potable water source for operations staff working at the project site.

Flooding FEMA prepares Flood Insurance Rate Maps that identify the locations of flood hazard areas. The map for Kern County indicates that approximately 378 acres (6.5% of the project site) along the low-lying areas of Cottonwood Creek are subject to flooding (Sapphos Environmental 2006b; Federal Emergency Management Administration 1986). This area is zoned by Kern County as Exclusive Agriculture, Geologic Hazard Combining, and Floodplain Combining (see Figure 4.9-2).



As shown in Figure 4.8-3, these areas are located in Flood Zone “A,” which is designated as 100-year flood potential with base flood elevations and flood hazards determined. Such areas maintain a 1% annual chance of flooding and a 26% chance of flooding over the course of 30 years. The remainder of the project site lies within Flood Zone “X” (previously identified as Flood Zone “C” and recently changed by FEMA), which is characterized as areas that have a less than 1% chance of flooding each year; areas that have a less than 1% chance of sheet flow flooding with an average depth of less than 1 foot; areas that have a less than 1% chance of stream flooding where the contributing drainage area is less than 1 square mile; or areas protected from floods by levees. As currently designed, the proposed project would locate several turbines and associated facilities, such as the transformers at the base of the turbines, underground electric lines, and access roads within Flood Zone “A” at the southeastern corner of the site, along 170th Street West (see Figure 4.8-3). Structures proposed for installation in flood zone areas must be reviewed by the Kern County Engineering and Services Department for approval prior to installation.

4.8.3 Regulatory Setting As discussed below under “Impacts and Mitigation,” the project would not have a significant impact on hydrology or water quality. The project has been designed to avoid federal wetlands and, following mitigation, would only have insignificant impacts on one blue-line drainage subject to the jurisdiction of the CDFG. The project would not involve any permanent impacts on surface waters. The project would be consistent with the plans, guidelines, and laws described below.

Kern County Kern County General Plan

The policies, goals, and implementation measures in the Kern County General Plan for hydrology and water quality applicable to the project are provided below. The Kern County General Plan contains additional policies, goals, and implementation measures that are more general in nature and not specific to development such as the proposed project. Therefore, they are not listed below, but, as stated in Chapter 2, “Introduction,” all policies, goals, and implementation measures in the Kern County General Plan are incorporated by reference.



1.3 Physical and Environmental Constraints (Land Use, Open Space, and Conservation Element) Policies

Policy 1. Kern County will ensure that new developments will not be sited on land that is physically or environmentally constrained (Map Code 2.1 [Seismic Hazard], Map Code 2.2 [Landslide], Map Code 2.3 [Shallow Groundwater], Map Code 2.5 [Flood Hazard], Map Codes from 2.6 – 2.9, Map Code 2.10 [Nearby Waste Facility], and Map Code 2.11 [Burn Dump Hazard]) to support such development unless appropriate studies establish that such development will not result in unmitigated significant impact.

Policy 6. Regardless of percentage of slope, development on hillsides will be sited in the least obtrusive fashion, thereby minimizing the extent of topographic alteration required and reducing soil erosion while maintaining soil stability.

Policy 7. Ensure effective slope stability, wastewater drainage, and sewage treatments in areas with steep slopes are adequate for development.

Policy 8. Encourage the preservation of the floodplain’s flow conveyance capacity, especially in floodways, to be open space/passive recreation areas throughout the County.

Policy 9. Construction of structures that impede water flow in a primary floodplain will be discouraged.

Policy 10. The County will allow lands which are within flood hazard areas, other than primary floodplains, to be developed in accordance with the General Plan and Floodplain Management Ordinance, if mitigation measures are incorporated so as to ensure that the proposed development will not be hazardous within the requirements of the Safety Element (Chapter 4) of this General Plan.

Policy 11. Protect and maintain watershed integrity within Kern County.

Implementation Measures Implementation Measure E. Development proposed in areas

with steep slopes will be reviewed for conformity to the adopted Hillside Development Ordinance to ensure that appropriate soil stability, drainage, and sewage treatment will result.

Source: Sapphos Environmental Inc., 2006

Figure 4.8-3Flood Zone Areas in the Project Site

PdV Wind Energy ProjectKern County, California

Ecology and Environment, Inc. 002147.EX09.01.d2(Gp2)(BW).ai (2007 Corp Archives CD - Vol 1) 04/11/2007

Cottonwood Creek

Cottonwood Creek

5 4 3 2 1

10 11 12

151617

23

252829

32 34 35 36

5 4 3 1

2120

1413

8 9

T9N – R15WT10N – R15WT9N – R15WT10N – R15W

2

33

2627

22

24

0 2,500 5,0001,250

Feet

Intermittent drainages

Project boundary

100-year flood zone(> 1% chance of flooding each year)

< 1% chance of flooding each yeararea with < 1% chance of sheet flow flooding,and average depth < 1 ft.; orarea with < 1% chance of stream flooding,where contributing drainage area is < 1 sq. mi.;or, area protected from floods by levees.

Flood Zones



Implementation Measure F. The County will comply with the Colbey-Alquist Floodplain Management Act in regulating land use within designated floodways.

Implementation Measure H. Development within areas subject to flooding, as defined by the appropriate agency, will require necessary flood evaluations and studies.

Implementation Measure I. Designated flood channels and water courses, such as creeks, gullies, and riverbeds, will be preserved as resource management areas or in the case of urban areas, as linear parks whenever practical.

Implementation Measure J. Compliance with the Floodplain Management Ordinance prior to grading or improvement of land for development or the construction, expansion, conversion or substantial improvements of a structure is required.

Implementation Measure N. Applicants for new discretionary development should consult with the appropriate Resource Conservation District and the California Regional Water Quality Control Board regarding soil disturbances issues.

1.9 Resources Policies

Policy 11. Minimize the alteration of natural drainage areas. Require development plans to include necessary mitigation to stabilize runoff and silt deposition through utilization of grading and flood protection ordinances.

1.10.6 Surface Water and Groundwater Policies

Policy 34. Ensure that water quality standards are met for existing users and future development.

Policy 40. Encourage utilization of community water systems rather than the reliance on individual wells.

Policy 41. Review development proposals to ensure adequate water is available to accommodate projected growth.

Policy 43. Drainage shall conform to the Kern County Development Standards and the Grading Ordinance.

Policy 44. Discretionary projects shall analyze watershed impacts and mitigate for construction-related and urban pollutants, as well as alterations of flow patterns and introduction of impervious surfaces as required by the



California Environmental Quality Act (CEQA), to prevent the degradation of the watershed to the extent practical.

Policy 46. In accordance with the Kern County Development Standards, tank truck hauling of domestic water for land developments or lots within new land developments is not permitted.

Implementation Measures Implementation Measure Y. Promote efficient water use by

utilizing measures such as:

i. Requiring water-conserving design and equipment in new construction.

ii. Encouraging water-conserving landscaping and irrigation methods.

iii. Encouraging the retrofitting of existing development with water conserving devices.

Kern County Ordinances Chapter 17.28 Grading Code Requirements of the Kern County Grading Code will be implemented. Of particular note with respect to hydrology and water quality is Section 17.28.140, Erosion Control, as discussed in Section 4.6, “Geology and Soils.” Chapter 19.64 Wind Energy Combining District Section 19.64.140(K): Prior to issuance of any grading permit, a plan for the mitigation of potential soil erosion and sedimentation shall be prepared by a registered civil engineer or other professional and submitted for approval by the Director of the Engineering and Survey Services Department. The soil erosion and sedimentation control plan shall be consistent with the applicable requirements of the California Regional Water Quality Control Board. Chapter 19.70 Floodplain Combining District Section 19.70.040: Prohibits the following uses in the Floodplain Combining District, as applicable to the proposed project: B. All uses that will likely increase the flood hazard or affect the

water-carrying capacity of the floodplain beyond the limits resulting from encroachment as specified in Section 19.70.130.

C. Dumping, stockpiling, or storage of floatable substances or other

materials which, in the opinion of the Kern County Engineering



and Survey Services Department, will add to the debris loads of the stream or watercourse, unless protected by flood control devices approved by the Kern County Engineering and Survey Services Department and constructed in accordance with Section 19.70.130.

D. Storage of junk or salvage operations. E. Oil storage tanks or processing equipment, unless floodproofed or

sufficiently elevated above the Base Flood Elevation, as determined by the Kern County Engineering and Survey Services Department.

F. Individual sewage disposal systems (e.g., septic tank systems),

unless protected by flood control devices approved by the Kern County Engineering and Survey Services Department and constructed in accordance with the requirements of the Kern County Health Department so as to minimize infiltration of floodwaters into the systems and discharges from the systems into the floodwaters.

G. Sources of water supply (e.g., wells, springs) unless protected by

flood control devices approved by the Kern County Engineering and Survey Services Department and constructed in accordance with the requirements of the Kern County Health Department so as to minimize infiltration of floodwaters.

State

Porter-Cologne Water Quality Control Act The Porter-Cologne Water Quality Control Act (Water Code Sections 13000 et seq.), passed in 1969, requires protection of water quality by appropriate designing, sizing, and construction of erosion and sediment controls. The Porter-Cologne Act established the State Water Resources Control Board (SWRCB) and divided California into nine regions, each overseen by a regional water quality control board. The SWRCB is the primary state agency responsible for protecting the quality of the state’s surface and groundwater supplies and has delegated primary implementation authority to the nine RWQCBs. The Porter-Cologne Act assigns responsibility for implementing Clean Water Act (CWA) Sections 401 through 402 and 303(d) to the SWRCB and the nine RWQCBs. The Porter-Cologne Act requires the development and periodic review of water quality control plans (basin plans) that designate beneficial



uses of California’s major rivers and groundwater basins and establish narrative and numerical water quality objectives for those waters, provide the technical basis for determining waste discharge requirements, identify enforcement actions, and evaluate clean water grant proposals. The basin plans are updated every three years. Compliance with basin plans is primarily achieved through implementation of the National Pollutant Discharge Elimination System (NPDES), which regulates waste discharges (see below). The proposed project site is located within the jurisdiction of the Lahontan RWQCB. The Basin Plan for the Lahontan region defines a variety of water quality objectives for the Fremont-Antelope Hydrologic Units, but Cottonwood Creek is not called out specifically and no specific beneficial water uses were listed (Lahontan Regional Water Quality Control Board 1994).

California Streambed Alteration Program The California Lake and Streambed Alteration Program, Section 1602 of the California Fish and Game Code, regulates activities that would “substantially divert or obstruct the natural flow of, or substantially change the bed, channel, or bank of, or use material from the streambed of a natural watercourse” that supports wildlife resources. The CDFG has authority to review and regulate all proposed alterations of streambeds.

Federal Clean Water Act

The CWA is intended to restore and maintain the chemical, physical, and biological integrity of the nation’s waters (33 Code of Federal Regulations [CFR] 1251). The regulations implementing the CWA protect waters of the U.S. or streams and wetlands (33 CFR 328.3). The CWA ensures that water quality within aquatic ecosystems is maintained at a level of integrity that enables biological resources to exist and function properly. The following paragraphs provide details on specific sections of the CWA. Section 401, Water Quality Certification Compliance with Section 401 of the CWA is required for applicants who require a Section 404 permit from the USACE because of potential discharges and impacts on waters of the U.S. or wetlands. If issued, a Section 401 certification from the SWRCB/RWQCB indicates that discharges and impacts will also comply with state water quality standards. The SWRCB has a policy of no net loss of wetlands in effect



and typically requires mitigation for all impacts on wetlands before it will issue a water quality certification or waiver thereof. Section 402, National Pollutant Discharge Elimination System Section 402 of the CWA regulates construction-related stormwater discharges to surface waters through the NPDES program, administered by the EPA with implementation authority delegated to the SWRCB in California. An NPDES permit is required for all projects that disturb more than 1 acre of land. Therefore, the proposed project would require an NPDES permit. As described above, the proposed project site is under the jurisdiction of the Lahontan RWQCB. As part of the permitting effort, the applicant would file a public notice of intent to discharge stormwater associated with the project. As part of the NPDES program, the applicant must develop a Storm Water Pollution Prevention Plan (SWPPP). As discussed in Section 4.6, “Geology and Soils,” the applicant is required to implement a Soil Erosion and Sedimentation Control Plan to comply with the Wind Energy Zoning Ordinance. This plan will include a description of the measures or best management practices (BMPs) to be implemented to prevent soil erosion and discharge of other construction-related pollutants that could contaminate nearby surface waters and wetlands. Permittees are further required to conduct annual monitoring and reporting to ensure that BMPs are correctly implemented and effective in controlling the discharge of stormwater-related pollutants. If this plan is to be used as the project SWPPP, it must meet the requirements of the NPDES General Permit for construction stormwater discharge. Section 303(d) List of Impaired Water Bodies Under CWA Section 303(d) and the Porter-Cologne Water Quality Control Act, the State of California is required to establish beneficial uses of state waters and to adopt water quality standards to protect those beneficial uses. Section 303(d) of the CWA lists streams and other waters of the United States that have “Water Quality Limited Segments,” or portions that do not meet water quality standards even after point sources of pollution have installed the minimum required levels of pollution-control technology. Under the CWA, the SWRCB establishes priority rankings for water on the lists and develops total maximum daily load criteria (i.e., the maximum quantity of a particular contaminant that a water body can assimilate without experiencing adverse effects) to improve water quality. On July 25, 2003, the EPA gave final approval to California's 2002 Section 303(d) List of Water Quality Limited Segments. There are no impaired water bodies in the



watershed of the proposed project. Cottonwood Creek is not listed on the 303(d) list (Lahontan Regional Water Quality Control Board 2002).

National Flood Insurance Act The National Flood Insurance Act was enacted in 1968 and the National Flood Insurance program was developed. Prior to this program, affordable private flood insurance was generally not available. Under the National Flood Insurance Act, federally subsidized flood insurance is made available to owners of flood-prone property in participating communities. The program is administered by the Federal Insurance Administration of FEMA. The program requires that participating communities adopt certain minimum floodplain management standards, including restrictions on new development in designated floodways, a requirement that new structures in the 100-year flood zone be elevated to or above the 100-year flood level (known as base flood elevation), and a requirement that subdivisions be designed to minimize exposure to flood hazards (National Oceanic and Atmospheric Administration 2006). To facilitate identifying areas with flood potential, FEMA has developed Flood Insurance Rate Maps that can be used for planning purposes, including floodplain management, flood insurance, and enforcement of mandatory flood insurance purchase requirements. As shown in Figure 4.8-3, the low-lying areas along Cottonwood Creek are in a flood hazard zone.

4.8.4 Impacts and Mitigation Measures Methodology

This section analyzes impacts on hydrology and water quality from the implementation of the proposed project based on changes to the environmental setting described above. Sapphos Environmental identified surface waters and wetlands in the project site by reviewing USGS topographic maps, aerial photography, and literature and by conducting field studies. The USACE 1987 Wetland Delineation Manual and the CDFG A Field Guide to Streambed Alteration Agreements were consulted to determine whether features met the parameters of jurisdictional waters of the U.S. or wetlands or waters of the state.

Thresholds of Significance The Kern County CEQA Implementation Document and Kern County Environmental Checklist state that a project would have a 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 pre-existing 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-site 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-site or off-site;

Create or contribute runoff water that 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 hazard area structures that would impede or redirect flood flows;

Expose people or structures to a significant risk of loss, injury, or death involving flooding, including flooding as a result of the failure of a levee or dam; or

Expose people or structures to a significant risk of loss, injury, or death due to inundation by seiche, tsunami, or mudflow.

Project Impacts Impact 4.8-1: Violate Any Water Quality Standards or Waste Discharge Requirements

Construction activities would disturb soils in the project site, making them more susceptible to erosion and more likely to be transported by stormwater runoff into nearby drainages, potentially affecting local and



downstream water quality. Sedimentation in surface waters and wetlands can reduce water-carrying capacity, potentially leading to flooding; degrade water quality; increase turbidity (concentration of suspended particles), thereby reducing light penetration and inhibiting photosynthesis; and introduce fertilizers and other nutrients, which can lead to eutrophication. Degradation of water quality in Cottonwood Creek and its tributaries is potentially significant as it could affect the water quality of Rosamond Lake, downstream of the project site. However, the amount of erosion and runoff into drainages at and in the vicinity of the project site is expected to be limited (as only approximately 6% of the project site would be graded), impacts from erosion and runoff are expected to be localized and temporary (i.e., during construction), and the applicant would implement measures to minimize and contain erosion and sedimentation in accordance with the Kern County Grading Code and project NPDES permit. As discussed in Section 4.4, “Biological Resources,” the applicant would limit grading to the minimum area needed to facilitate safe construction and operation. As described above, no turbines or other aboveground buildings would be sited within surface waters; however, the applicant has identified 38 locations where access roads would cross drainages (see Figure 4.8-2). At these locations, there would be an increased potential for pollutants to enter the feature and degrade water quality. Soil could build up in the dry wash bed at access road crossings and be carried downstream or off-site during a rain event. Three of these crossings occur at Cottonwood Creek, which is the only jurisdictional drainage (water of the state) in the project site.

Because the project would disturb more than 1 acre, the applicant would be required to obtain and comply with the NPDES regulations for surface discharge by acquiring a general construction stormwater discharge permit. As required by this permit, the applicant would have to develop a SWPPP and comply with any regional requirements to meet state water quality objectives. The applicant would also be required to develop and implement a Soil Erosion and Sedimentation Control Plan as discussed in Section 4.6, “Geology and Soils,” which would identify measures such as silt fences and straw bale sediment barriers to prevent runoff of soils and other pollutants. (This plan could also be used for the SWPPP if it meets the requirements of the NPDES General Permit.) Implementation of a project-specific Soil Erosion and Sedimentation Control Plan would reduce the project’s potential to violate water quality standards or waste discharge to a less-than-significant level.



Water quality of drainages within the project site would also be degraded if hazardous materials (e.g., gas, hydraulic fluid, and paints) introduced to the area during construction and operation were released to the environment and transported into the drainages and aquifers by stormwater runoff. To prevent hazardous materials from entering drainages and affecting water quality, the applicant would be required to implement a Hazardous Materials Business Plan and submit it to the Kern County Environmental Health Services Department for review, as discussed in Section 4.7, “Hazards and Hazardous Materials.” As described in this plan, all hazardous materials would be properly stored, handled by trained individuals, and disposed of in accordance with applicable laws and regulations. This would reduce potential impacts on water quality from a release of hazardous materials to a less-than-significant level. The project would not cause a new point discharge source. As discussed in detail in Section 4.16, “Utilities and Services,” the project would include a septic system and leach field. The applicant would locate the leach field a minimum of 100 feet from the banks of any watercourse, per the setback requirements of Chapter 19.70 (Floodplain Combining District) of the Kern County Zoning Ordinance. The applicant would be subject to the mitigation measures below to ensure that impacts on water quality remain less than significant. Mitigation Measures MM 4.8-1. The applicant shall provide environmental training to all construction personnel. The training shall emphasize the importance of protecting water quality and shall review the requirements of the project NPDES permit and Hazardous Materials Business Plan. MM 4.8-2. The applicant shall complete the installation of the box culverts at the two crossings of the Los Angeles Aqueduct in as short a time period as practicable to minimize any temporary construction effects associated with the use of equipment containing hazardous materials that could be released into the aqueduct. MM 4.8-3. Prior to the issuance of a grading permit for any work on the access road and drainage crossings, the applicant shall submit an appropriate drainage and/or flood hazard study to the Kern County Engineering and Survey Services Department for review and approval. The study shall include, but not be limited to, the following provisions at the location of access road and drainage crossings:



a. Ensure that soils do not accumulate in drainage beds at the gravel and dirt road crossing locations during construction and throughout operation of the project;

b. Use fill ramps rather than bank cutting to minimize impact on water quality affected by increased erosion;

c. Design access road and drainage crossings to accommodate the runoff of a 10-year storm system; and

d. Periodically check access road crossing locations during construction and throughout operation for spills of hazardous materials, and clean up all spills.

MM 4.8-4. The applicant shall site all storage of hazardous materials and conduct any refueling at least 100 feet away from the NWI-mapped wetlands and Cottonwood Creek. MM 4.8-5. The applicant shall set back all soil stockpiles at least 10 feet from the NWI-mapped wetlands and drainages. MM 4.8-6. If required, the applicant shall obtain a streamlined alteration agreement from the California Department of Fish and Game. Level of Significance after Mitigation Impacts would be less than significant.

Impact 4.8-2: Deplete Groundwater Supplies or Interfere with Groundwater Recharge

The proposed project may include the construction of a water well in order to supply water to the project personnel during construction and operation. Water usage would be greatest during peak construction, which would be limited to several months and would not be expected to require a large quantity of water. As a staff of only 10 to 16 would be required to work on-site during operation, the amount of water withdrawn is expected to be minimal. Therefore, use of water from this well would have a less-than-significant impact on groundwater. Installation of the wind turbines and associated facilities would have a less-than-significant impact on groundwater because excavation for facility foundations would not reach groundwater depths, which are estimated to be 200 to 300 feet deep in the project area. The project would permanently disturb approximately 276.8 acres or 4.8% of the project site. However, only building foundation areas would be converted to impervious surfaces. These areas are estimated to total approximately 13 acres (or 0.2% of the entire project site), based on a



75-square-foot area for each turbine foundation, a 0.1-acre footprint for the operations and maintenance building, and 12.4-acre footprint for the PdV substation. Because the proposed project would not involve a substantial increase in impervious surfaces, the proposed project would have a less-than-significant effect on groundwater recharge. It should be noted that the Los Angeles County Water Works has filed suit against several large agricultural operations because of the overdraft problems in the area (Flood 2005). As a result of this lawsuit and other concerns with development demands on groundwater in the Antelope Valley groundwater sub-basin, uses of groundwater, such as the well for the project, could potentially be regulated more strictly by a Watermaster designated by court decision. In this case, the applicant’s water well permit may be affected at a future date. Mitigation Measures The project would comply with the goals, policies, and implementation measures of the Kern County General Plan. No additional mitigation measures are proposed. Level of Significance after Mitigation Impacts would be less than significant.

Impact 4.8-3: Result in Impacts on the Existing Drainage Patterns

Although the applicant would not locate turbines or other aboveground buildings within drainages (see Figure 3-1), construction of access roads across blue-line drainages at 38 locations would alter the drainage pattern at the immediate road crossing location. Because Cottonwood Creek is a water of the state, a 1602 Lake and Streambed Alteration Agreement would be required from the CDFG to allow for impacts on a cumulative 0.1 acre of this drainage at the three proposed access road crossings. To reduce impacts on the drainages and, thereby, existing drainage patterns, the applicant has developed a typical dry-wash crossing method, as illustrated in Figure 4.8-4, that minimizes grading of the drainages banks and installs rock along the bed of the drainage. This proposed design method would allow for flow in the event of a storm while minimizing the potential for banks to collapse or the bed to become scoured because of loosening of the soils from equipment access. Because water would be allowed to flow over the access road crossings as it does currently, impacts on drainage in the site would be less than significant. Keeping the access road crossing clean would prevent build-up of soil that could affect drainage in the project site in the event of flow, including flooding.



As discussed above, short-term increases in erosion (including sedimentation build-up caused by access roads) as a result of ground disturbance would be minimized via implementation of the project-specific Soil Erosion and Sedimentation Control Plan and/or SWPPP in accordance with NPDES requirements. Construction and operation of the project would not require permanently altering the course of any of the blue-line drainages. Therefore, there would be no long-term effect on drainage patterns in the project that could result in substantial erosion and siltation on- or off-site. Mitigation Measures Implement MM 4.8-3, MM 4.6-11, and MM 4.6-12 (see Section 4.6, “Geology and Soils”). No additional measures are proposed. Level of Significance after Mitigation Impacts would be less than significant.

Impact 4.8-4: Alter Existing Drainage Patterns of the Site or Area, Causing Flooding

The gradual sloping of the project site causes water to drain toward Cottonwood Creek, which naturally reduces the potential for flooding in the project site and vicinity. As described above, a limited area of the project site along Cottonwood Creek and in the southeastern corner (5.9%) is in Flood Zone “A,” which is designated as 100-year flood potential with base flood elevations and flood hazards determined. This area has a 1% annual chance of flooding and a 26% chance of flooding over the course of 30 years. Based on field surveys, this area appears to flood during only extreme events (Sapphos Environmental 2006b).

1%

A

B

B

A

1%6'Access road

Access road profile

Access road profile

Extend rock road base to highwater mark of stream

Channel

Section A-ANo Scale

Flow

6' Rock 12" DPwith 3 sack cement sand slurryor filler approved by the engineer

Section A-ANo Scale

CL

ChannelCL

Figure 4.8-4

Typical Dry Wash Access Road Crossing SchematicPdV Wind Energy ProjectKern County, California


Source: Power Partners Southwest LLC, 2006

002147.EX09.01.r.ai (2006 Corp Archives CD - Vol 3) 10/09/2006



As described above, drainages in the project site would be impacted at access road crossings. The applicant would prevent the build-up of soils in the drainages, which would reduce the potential for local flooding. In addition, the primary way to reduce flooding is to slow runoff entering streams. The applicant would implement erosion and sediment control measures to reduce runoff, thereby preventing local flooding. Because the project would not involve altering the course of drainages in the project site, the project is not likely to increase the potential for flooding beyond existing conditions. Therefore, this impact would be less than significant. Mitigation Measures Implement MM 4.8-3, MM 4.6-11, MM 4.6-12 (see Section 4.6, “Geology and Soils”), and MM 4.8-7 below. Level of Significance after Mitigation Impacts would be less than significant.

Impact 4.8-5: Result in Impacts on Runoff Water and Drainage Capacity

The project would increase impervious surfaces by approximately 13 acres, which is only 0.2% of the entire project site. This limited increase in impervious surface is not expected to increase stormwater runoff or affect existing drainage in the project site. Road construction or expansion can also increase water runoff rates, resulting in accelerated soil erosion. The applicant would implement applicable building codes during road construction to ensure appropriate drainage. The soils in the project site are all classified by the Natural Resources Conservation System as hydric soil group B. These soils are characterized as having a moderate infiltration rates when thoroughly wet, and runoff is relatively low. Therefore, this impact would be less than significant. Mitigation Measures The project would comply with the goals, policies, and implementation measures of the Kern County General Plan. No additional measures would be required. Level of Significance after Mitigation Impacts would be less than significant.



Impact 4.8-6: Place Within a 100-Year Hazard Area Structures that Would Impede or Redirect Flood Flows

As described above, the project would involve installation of turbines and associated facilities, including transformers at the base of the turbines, underground electric lines, and access roads within Flood Zone “A GH FPS,” zoned by Kern County as Exclusive Agriculture, Geologic Hazard Combining, Floodplain Combining in the southeastern corner. The proposed designated yard in the southwestern corner of the project is located immediately adjacent (southwest) of Cottonwood Creek and the associated flood hazard zone overlying this feature. A permanent building may or may not be located at this yard, based on final facility siting. Kern County allows for installation of structures within a 100-year hazard area (Scheer 2006); however, additional conditions may be applied to the building permit, such as requiring the installation of structures with electrical equipment to be above natural grade or setting a foundation depth for underground equipment. This impact would be potentially significant and mitigation is required. Mitigation Measures MM 4.8-7: As required by Section 19.70.070 (Kern County Floodplain Combining District –Yards and Setbacks) of the Kern County Zoning Ordinance, the applicant shall locate all structures and facilities a minimum of 10 feet back from all waterways to avoid impediment or redirection of flood flow. Level of Significance after Mitigation Impacts would be less than significant.

Impact 4.8-7: Result in Impacts Caused by Seiche, Tsunami, or Mudflow

Because of the inland location of the project site and elevation, the potential for tsunami-related damage or a seismic seiche is low. The lands within and surrounding the project site are not subject to mudflows or other forms of natural slope instability because of the dense, relatively hard, and massive nature of the crystalline bedrock underlying the mountainous portion of the proposed project site. No impacts would occur. Mitigation Measures The project would comply with the goals, policies, and implementation measures of the Kern County General Plan. No additional mitigation measures are proposed.



Level of Significance after Mitigation Impacts would be less than significant.

Impact 4.8-8: Expose People or Structures to a Significant Risk of Loss, Injury, or Death involving Flooding

The project would not expose people or structures to a significant risk of loss, injury, or death involving flooding. As discussed in Impacts 4.8-4, and 4.8-5 above, only a limited area of the project site is in the 100-year flood zone, and project construction would increase impervious areas by less than 1 percent of the site area. In addition, the natural soil conditions include moderate infiltration rates and relatively low runoff rates, which naturally mitigate flooding potential. Therefore, this impact would be less than significant. Mitigation Measures The project would comply with the goals, policies, and implementation measures of the Kern County General Plan. No additional mitigation measures are proposed. Level of Significance after Mitigation Impacts would be less than significant.

Impact 4.8-9: Result in Impacts on Hydrology and Water Quality as a Result of SCE Facility Improvements

As described in Section 3.5 under “SCE Regional Special Protection Scheme for Early Interconnection,” SCE would construct the Cottonwind substation (switchyard) in Section 4 of the southwestern portion of the wind energy project site. The associated facilities for the Cottonwind substation (switchyard) include transmission line, station light and power, and telecommunication channels. Two telecommunications channels would support the proposed Cottonwind substation and the Special Protection Scheme. The first channel would require the installation of 22.3 miles of new fiber optic cable between the existing Rosamond substation, the proposed Cottonwind substation, and the existing Antelope substation. Most of the 22.3 miles would use existing poles, requiring only the addition of a single cable to the existing six lines. The second proposed channel would require the installation of a 110-foot-high microwave tower and new microwave telecommunications system for communication between Cottonwind and Antelope substations.



Impacts Construction can expose bare soils, resulting in wind and water erosion. In addition, stormwater runoff can exacerbate erosion and transport soils and construction debris and contaminants to other areas as well as to receiving waters. The SCE facilities improvement area is very gradually sloping but generally flat, and features no rivers, creeks, or watercourses. In addition, the project would occur almost entirely along existing roads and mostly in areas already altered for agricultural and other land uses, and would not involve actions that alter storm runoff drainage patterns. Regardless, the water quality measures cited in Section 3.5 under “Impact Avoidance Protocols for the SCE Regional Special Protection Scheme” would be enacted as part of the project to ensure against violating water quality standards or waste discharge requirements. Project measures would prevent discharge of wastes or contaminants, control for erosion, and protect nearby water quality. Therefore, the project would have no impact on hydrology and water quality, and groundwater supplies would not be affected by the project. No mitigation would be necessary. Level of Significance after Implementation of Impact Avoidance Protocols Impacts would be less than significant.

Impact 4.8-10: Contribute to Cumulative Impacts on Hydrology and Water Quality

The applicant has designed the proposed project to minimize impacts on hydrology and water quality by limiting the area of grading and avoiding installation of facilities in surface waters, with the exception of access road crossings. Any potentially adverse impacts on water quality during construction caused by the installation of access roads and grading would be mitigated through implementation of the project-specific Soil Erosion and Sedimentation Control Plan (see Section 4.6, “Geology and Soils”) and the mitigation measures above. Although the project would add approximately 13 acres of impervious surfaces, this is less than 0.02% of the entire project site and would not significantly increase impervious area and contribute to a significant impact on water quality. Further, the drainages in the project site either terminate in the project site or, in the case of Cottonwood Creek, just south of it. Therefore, the project would not contribute to a significant cumulative impact on hydrology and water quality in conjunction with the other proposed projects as listed in Chapter 3, “Project Description.” In addition, the other projects listed in Chapter 3, “Project Description," would have no relation to impacts on Cottonwood Creek or overall drainage in the project site because they are located more than 8 miles



away. Therefore, no apparent significant cumulative impacts are anticipated. Mitigation Measures Implement MM 4.8-1 through MM 4.8-7. Level of Significance after Mitigation Cumulative impacts would be less than significant.

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