Adapting to A Changing Climate: A Local Restoration Case Study

Mulhockaway Creek, Union Twp. NJ (Photo: Bruce Litton)

Climate Change

Hurricane Irene made landfall in New Jersey in August 2011, causing roughly $1 billion

in damage to 200,000 homes and other structures, many of them located in the northern and

central regions of the state. Irene was the costliest disaster in state history until Hurricane Sandy

hit the region the following year. Despite Sandy’s greater notoriety and damage to iconic coastal

communities, Irene’s impact on New Jersey’s inland regions cannot be forgotten.

A period of unusually heavy rainfall in the three weeks leading up to Irene exacerbated

flooding conditions. During this time, 8-16 inches of rain inundated the region, 150-600 percent

above normal levels.1 Irene then dumped an additional 10 inches in two days. The saturated

grounds could not absorb the brunt of the rainfall. Instead, waterlogged soil forced it into

waterways, leading to widespread flooding, property damage, and stream bank erosion. That

August now stands as the wettest month in New Jersey since records began in 1895, spanning

over 1,440 months.2

Some may argue this can be interpreted as a naturally-occurring record, bound to be

broken at one time or another. However, the Office of the New Jersey State Climatologist at

Rutgers University reports an upward trend in both long-term temperatures and annual rainfall

over the northern half of the state since 1895, particularly after 1970 (Figures 1, 2).3, 4 This

makes sense, as warmer weather results in greater evaporation and the atmosphere’s ability to

hold more moisture. Unfortunately this promotes more frequent intense precipitation events in

certain areas, including northern New Jersey.5 In general, the likelihood and intensity of flooding

events grows as an area’s average annual rainfall increases.6

Increased Development and Stronger Storms

Local development further increases flooding risks. Land development often involves

removing vegetation and making changes to ground cover. As it rains, much of the runoff is

normally slowed by plants and seeps into the soil instead of waterways, resulting in lower peak

stormwater flows. Rainfall washes away in larger quantities quicker in developed areas where

vegetation is removed, including parking lots and roadways. The more these braking

mechanisms are disturbed, the likelier storms result in flooding.7

Addressing the Issue

Given the evidence, it isn’t a question of whether a similar disaster will hit the region

again, but when. In fact, Irene and Sandy were ultimately classified as only considered tropical

storms when they hit New Jersey. Fortunately, public acceptance of the concept of manmade

climate change has shifted dramatically in recent years. Irene and Sandy are often used as

“teachable moments” in the discussion over regional vulnerability to natural disasters.8,9 Threats

posed by increasing populations and continued development are prompting communities to take

action through adaptations and resiliency projects.

Flooding events allow chemical pollutants, potentially dangerous microorganisms and

debris to wash into the water supply.10 Fast-moving waters also accelerate erosional processes in

neglected areas, increasing sediment that ultimately must be removed before reaching our

faucets. Not only do more intense floods increase contamination and strain water treatment

services, they heighten the risk of property damage and physical harm to residents.11

Restoration projects involving deteriorating waterways can mitigate these problems and

improve the ecological health of affected areas. Landscape alterations allow environments such

as wetlands to again provide key natural services such as the filtration of excess nutrients and

other pollutants before they enter our waterways, oftentimes reducing long-term treatment

costs.12 Waterway restoration efforts provide resiliency against stronger storms, allowing natural

services to ease the pressure placed on water treatment plants, bridges and other infrastructure.

A Local Restoration Case Study

Restoration of this sort has been done locally, even before widespread concern over long-

term shifts in the water cycle. One notable example is the Hoffman Park stream restoration

project in Union Township in Hunterdon County, NJ. From June to September 2006, consultants

and engineers contracted by the New Jersey Water Supply Authority (NJWSA) addressed

numerous water quality issues stemming from structural deficiencies in the Mulhockaway Creek,

which was found to be “severely degraded and unstable.”13 This location is one of two critical

tributaries into the Spruce Run Reservoir, part of a water supply network that delivers over 240

million gallons of water daily to 1.5 million residents of northern and central New Jersey.14

Components of the Project

The project’s components worked to restore the natural hydrology of a 700-foot section

of the creek (Table 1). The previously straightened creek resulted in higher water velocities,

increasing the likelihood of downstream flooding. Engineers increased the curvature, allowing

water to “pinball” back and forth into root wads and other newly installed instream structures

(Figure 3). These felled trees and similar engineering tools shield the outer banks of these curves,

dissipating kinetic energy that normally builds in straight channels.

Previously, high flow rates created a deeply incised channel, preventing water from

reaching its adjacent floodplain (Figure 4). In response, engineers raised the stream bed in order

to reconnect the creek’s flow to a wide floodplain. Now stormwater more readily spills over and

seeps back into the soil; momentum is slowed as water flows downstream, mitigating erosion

and flooding.

Additionally, steepened banks were regraded and planted with native grasses, trees and

shrubs to stabilize the soil. This adjacent vegetation naturally slows and filters stormwater

(Figure 5), removing many contaminants that would otherwise require treatment at higher long-

term costs.15

Lastly, a deteriorating culvert beneath a road prevented the proper passage of water,

sediment and debris, causing upstream congestion and bank erosion (Figures 6, 7). This became

a pressing concern not only due to impaired water quality, but it also undermined the stability of

the bank and road. Underground pipes were replaced with an arch culvert, which is essentially a

bridge. Heavy flows now pass unobstructed, eliminating clogging and flooding issues (Figure 8).

Local officials may choose from a suite of options in order to meet as many goals as

possible within budgetary constraints. While doing nothing saves costs in the short-term, it

leaves the environment susceptible to further degradation. This may force the problem to be

addressed at higher costs in the future. On the other hand, managers may go all-in by addressing

every single deficiency, striving to save money over time. Ultimately it depends on the most

pressing needs of each project – maybe one area requires replanting, another only a culvert

replacement to improve water passage. Not all projects need a full overhaul, meaning costs can

be saved in some areas while still minimizing the most urgent threats to public health and safety.

Making It Happen

While the Hoffman effort continues to help protect regional water quality, it was also a

successful first test of the newly implemented Highlands Water Protection and Planning Act

(2004). Intended to preserve natural resources and open space, the Act restricts development in

New Jersey’s Highlands region; a permit is required for those seeking to make major land

modifications – including waterway restoration projects. The New Jersey Water Supply

Authority (NJWSA) and Department of Environmental Protection’s (NJDEP) Division of

Watershed Management successfully argued for a waiver under the Health & Safety exemption

of the Highlands Act, claiming it would work to both restore a severely degrading environment

and protect residential health and property.16

Looking to the Hoffman project’s clear environmental and financial benefits, local

officials should support preliminary investigations into the feasibility of similar undertakings.

With the guidance of potential partners such as the NJWSA, NJDEP, and Raritan Headwaters

Association, conducting an initial cost-benefit analysis can help gauge the worth of investing in

forested headwater stream restoration and protection.

A $1 million EPA grant funded preliminary assessments of water bodies feeding into

Spruce Run Reservoir, with the rest going toward three local projects, including Hoffman Park.

The Hoffman Park project reportedly cost approximately $500,000, much of it for the arch

culvert, which raised the average restoration cost per stream-foot relative to similar projects.

NJDEP’s co-signing onto the project in support of the Health & Safety exemption enabled

NJWSA to waive the vast majority of permit fees, saving roughly $18,000.17

Today, grants from the EPA, NJDEP, and Highlands Council support efforts aimed at

nonpoint source pollution control, environmental infrastructure and flood hazard reduction and

resiliency.18, 19, 20 Municipalities are highly encouraged to assess their eligibility for restoration

potential and related funding. This is especially important when considering the possibility of

losing project funds for violating federal and state laws such as the Clean Water Act.21 For

instance, the Highlands Council provides an average of $28,000 and $60,000 to municipalities

seeking to conform to stream restoration and water use and conservation plans, respectively.22 It

would be wise to take advantage of various sources of financial assistance to bring about social

and environmental benefits, rather than allowing continued decreases in water quality and

potentially losing funding to address the same issue later on.

The takeaway is that stream restorations and similar endeavors are different from

traditional development proposals the Highlands Act seeks to regulate. Because language in the

Act isn’t geared towards remediation work, permit reviewers may be unfamiliar with specific

components of construction processes and project goals. The point is, sustained partnerships

among the state, watershed management organizations and local officials play an important role

in navigating the permitting process, obtaining various grants to greatly offset costs, and

ensuring post-construction benefits for many years to come.

Appendix

FIGURE 1: Annual precipitation in northern New Jersey (1895-2014). Note the rising average means, particularly after 1970, brought about by more extreme weather events occurring in the last 40+ years. (ONJSC)

FIGURE 2: Average annual temperatures in northern New Jersey (1895-2014). Note that rising temperatures follow a pattern similar to annual precipitation in Figure 1; the scientific community attributes this atmospheric warming to increasing concentrations of greenhouse gas emissions. (ONJSC)

Figure 3: Meanders installed during construction, improving stream sinuosity. Note root wads situated outside bends, helping to dissipate water energy and reduce erosion. (Photo: Kathy Hale, NJWSA)

Figure 4: Pre-restoration conditions downstream of culvert (2006). Note deep vertical incisions along banks due to severe erosion, and fallen trees. (Photo: Kathy Hale, NJWSA)

Figure 5: Looking across Mulhockaway Creek from the bridge (October 2015). Vegetation serves to effectively slow stormwater and filter out contaminants. Note the progress in growth less than a decade after construction, when Figures 3 and 9 were taken (Photo: Sam Rosen, RHA)

Figure 6: Looking upstream from the bridge (October 2015). Note dense vegetative growth, providing shade, wildlife habitat, and resiliency against flooding and pollution. (Photo: Sam Rosen, RHA)

Figure 7: A deteriorating, undersized culvert system altered the natural hydrology of Mulhockaway Creek pre-restoration (photo taken downstream). Such conditions inhibited adequate water flows, creating flooding, erosion, and pollution issues upstream of the culvert. (Photo: Kathy Hale, NJWSA)

Figure 8: The effects of an inadequate culvert system running underneath a roadway (indicated in Figure 7, above). Note the widening bank on the right, as well as erosion and exposed roots on both sides upstream of the culvert. (Photo: Kathy Hale, NJWSA)

Figure 9: Note the high discharge flowing freely underneath the newly installed arch culvert without any spillage or overflow. Compare this discharge to what the old culvert was expected to handle, as indicated in Figures 7 & 8 (Photo: Kathy Hale, NJWSA) Table 1: Individual restoration components and their benefits

Component Benefits

Installation of instream structures in strategic locations (rock, cross and log vanes, root wads)

Redirect stream flow in order to slow speed, reducing erosion and stabilizing stream banks. Also promotes

healthy aquatic habitats.

Biostabilization through slope regrading and vegetative planting (coir fiber matting to support a mix of native

grass seeds, installation of native trees and shrubs)

Stabilizes surrounding soils and reduces erosion, filters pollutants entering creek, slows down floodwaters,

provides shading and habitat.

Increased stream sinuosity

Forces water to bounce back and forth, slowing down flow and reducing erosion and incidences of flooding.

Raised stream bed

Causes water to spill back over the banks more readily, where vegetation slows it down and allows it to seep into soil. This reduces the amount of water making its

way downstream, mitigating erosion and flooding.

Installation of arch culvert

Acting as a bridge, new culvert enables easy passage of water, sediment, debris downstream, including heavy stormwater flows, mitigating flooding and upstream

erosion. Also facilitates crucial trout passage.

Table 2: Social and environmental benefits of stream restoration projects

Social

Environmental

Boosts long-term resiliency to future weather events

Reduced flooding

Reduced water treatment costs Reduced pollution

Reduced property damages Reduced stream bank erosion

Compliance with water quality standards, such as federal Clean Water Act

Improved wildlife habitat and biodiversity

Recreation (i.e. hiking, fishing)

Enhanced aesthetics and property values

Publicity for municipalities

Increased public awareness of environmental issues

Project Timeline

• 2003: EPA provides organizations with $1 million Targeted Watersheds Grant to conduct

preliminary assessments of the watershed

• Summer 2004: Pre-project monitoring for macroinvertebrates, vegetation, substrate analysis,

geomorphology begins

• June 2006: Highlands Preservation Area Approval Permit application from NJDEP approved,

construction begins

• September 2006: Construction completed

• October 2006: NJWSA wins New Jersey Association for Floodplain Management’s

“Outstanding Floodplain Management” award for work done at Hoffman Park

• November 2006: Vegetative planting

• December 2006: NJWSA carries out adaptive maintenance in response to several large

storms in October and November

• March 2007: NJWSA wins American Council of Engineering Companies of New Jersey’s

“Award for Engineering Excellence” for work done at Hoffman Park

• October/November 2007: Additional vegetative planting

• Fall 2011: Post-project monitoring for macroinvertebrates, vegetation, substrate analysis,

geomorphology ends

Endnotes

1 USGS, 2013 2 Ibid 3 ONJSC, 2015 4 ONJSC, 2015 5 New Jersey Department of Environmental Protection, 2013 6 Doswell, 2003 7 Ibid 8 Leiserowitz et al., 2012 9 United States Global Change Research Program, 2014 10 Doswell, 2003 11 Ibid 12 EPA, 2012 13 Louis Berger Group, 2006 14 NJWSA, n.d. 15 The Nature Conservancy, 2015 16 Louis Berger Group, 2006 17 Ibid 18 NJDEP, 2015 19 NJDEP, 2015 20 NJDEP, 2015 21 Star Ledger Editorial Board, 2015 22 New Jersey Highlands Council, 2015

Works Cited

Benefits of Floodplain By Design. The Nature Conservancy, 2015. Web.

Christie’s Attack On Clean Water. Star Ledger Editorial Board, 6 September 2015. Web.

Climate Change in New Jersey: Trends in Temperature and Sea Level. Office of Science, New Jersey Department of Environmental Protection. June 2013. Web.

Doswell, Charles III. Flooding. University of Oklahoma, 2003. Web.

Environmental Infrastructure Financing Program. New Jersey Department of Environmental

Protection, Grant & Loan Programs, 23 January 2015. Web.

Evaluating the Cost Effectiveness of Restoration. United States Environmental Protection Agency, 6 March 2012. Web.

Final Design Report: Hoffman Park Stream Restoration Project. Louis Berger Group, September 2006. Print.

Flood Hazard Risk Reduction and Resiliency Grant Program. New Jersey Department of

Environmental Protection, Grant & Loan Programs, 13 October 2015. Web.

Leiserowitz, A., Maibach, E., Roser-Renouf, C., Feinberg, G., & Howe, P. Climate Change in the American Mind: Americans’ Global Warming Beliefs and Attitudes in September 2012. Yale University & George Mason University, 2012. Web.

National Climate Assessment. Northeast. United States Global Change Research Program, 2014. Web.

Nonpoint Source Pollutions Control Grants (319 Grants). New Jersey Department of

Environmental Protection, Grant & Loan Programs, 23 January 2015. Web.

Northern NJ Annual Precipitation (1895-2014). Office of the New Jersey State Climatologist,

Rutgers University, 12 October 2015. Web.

Northern NJ Mean Annual Temperature (1895-2014). Office of the New Jersey State

Climatologist, Rutgers University, 12 Oct. 2015. Web.

Raritan Basin Water Supply System. New Jersey Water Supply Authority, n.d. Web.

Summary of Flooding in New Jersey Caused by Hurricane Irene, August 27–30, 2011. New

Jersey Water Science Center, United States Geological Survey, 14 January 2013. Web.

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March 31, 2015. Web.