Stream Assessment & Restoration in the Spruce Run Reservoir Watershed

What are you doing with those hip waders?

That was the question asked of the New Jersey Water Supply Authority watershed staff over the past several months as they conducted approximately 40 stream visual assessments in the Spruce Run Reservoir Watershed and identified several potential restoration sites.

In 2003, the Stony Brook-Millstone Watershed Association (SBMWA) and the New Jersey Water Supply Authority (NJWSA) received a Targeted Watersheds Grant from the United States Environmental Protection Agency (EPA).  The project focuses on three types of strategies in the Raritan Basin:  restoration at locations with existing problems, protection and preservation of high-quality resources and pollution prevention focused on ongoing nonpoint source discharges.  The project partners include the South Branch Watershed Association (SBWA) and the New Jersey Department of Environmental Protection (NJDEP).  This article focuses on the stream assessment and restoration activities in the South Branch project area.

NJWSA used the United States Department of Agriculture – Natural Resources Conservation Service (USDA-NRCS) Stream Visual Assessment Protocol (SVAP) to gather baseline data for this project.  Training was provided by Tim Dunne of NRCS.  The SVAP is used to score a site based on a set of indicators, including:

Õ Condition of the stream channel – channelization, presence of riprap, downcutting or incision Õ Hydrologic alteration (dams or other structures) Õ Riparian zone (extent of natural vegetation) Õ Stability of stream banks Õ Water appearance Õ Nutrient enrichment (presence of algae) Õ Barriers to fish movement (dams/culverts) Õ Instream habitat for fish and macroinvertebrates Õ Presence and abundance of pools Õ Presence or absence of macroinvertebrates  Õ Canopy cover (percent shading of water surface), and Õ Riffle embeddedness (amount of sediment in the stream)

SVAP Sites and Results:  Approximately forty SVAP locations were chosen on four streams within the 40-square mile watershed draining to Spruce Run Reservoir:  Willoughby Brook, Spruce Run, Rocky Run and Mulhockaway Creek.  The objective was to collect enough information to assess overall stream health and to identify potential restoration sites.  NJWSA staff chose sites that would help provide a comprehensive assessment of each of the four streams by identifying significant land use patterns along each stream. 

The assessment team observed several problems throughout the watershed.  Many sites received low riparian zone scores due to the presence of invasive species and the lack of an adequate riparian buffer.  Severe bank erosion due to high flow events was also observed at many sites.  The majority of the sites scored relatively high for macroinvertebrates, particularly when the time of year (late fall and winter) was taken into account. 

Twenty sites on Mulhockaway Creek were assessed: 1 ranked good, 16 ranked fair, 3 ranked poor.  

Ten Spruce Run sites were assessed: 3 ranked good, 6 ranked fair, 1 ranked poor. 

Four Willoughby Brook sites were assessed: 1 ranked good and 3 ranked fair. 

Four Rocky Run sites were assessed: 2 ranked good, 2 ranked fair.

No clear trend (e.g. upstream to downstream) was seen on any of the streams.  The lower scores tended to be due to low riparian zone, bank stability, the presence of sediment, channel condition and nutrient enrichment scores.

Following completion of the initial set of SVAPs, staff reviewed the results and classified each site based on the need for restoration and the feasibility of restoration under this project.  From the initial set of sites, two areas were selected for restoration under the EPA grant.  Additional areas will be targeted for restoration in the future.

Spruce Run:  SVAP #32 and #33 are, respectively, on the downstream and upstream side of a private road crossing.  The property surrounding these two sites was recently purchased by NJWSA and a consortium of municipal and nonprofit entities and will be preserved as open space. A pipe culvert underneath the private road will be replaced in order to improve water flow through the culvert and to improve fish passage.

Mulhockaway Creek:  SVAP #21 is located within Hoffman Park, which is owned and managed by Hunterdon County.  The upstream portion of the reach appears to have been straightened, and there is some bank erosion.  The downstream portion of the reach has banks up to five feet, is disconnected from the floodplain and exhibits significant sediment transport.  Various structures will be installed to reduce the erosive forces and more closely mimic natural flow patterns.  In addition, the pipe culvert at the road crossing will be replaced with a crossing that permits more natural water flow.

Next Steps:  NJWSA has been working with the Delaware River Basin Commission to complete a geomorphological analysis of the two selected restoration sites.  Staff has been working to survey and identify features such as bankfull depth, entrenchment ratio and channel sinuosity.  These features will be utilized to design appropriate in-stream measures for each site.  Staff anticipate beginning construction in June, 2005.

Submitted by Kathy Hale, New Jersey Water Supply Authority

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