ESTABLISHING A TEMPERATURE DISCHARGE RELATIONSHIP TO ADDRESS TEMPERATURE IMPAIRMENT IN THE PEQUANNOCK RIVER, NEW JERSEY FOR TMDL DEVELOPMENT

In September 2004, The New Jersey Department of Environmental Protection (Department) submitted 13 temperature TMDLs for the Pequannock River Watershed to EPA for approval. The TMDL calculations were based on a temperature-discharge relationship using regression and SSTEMP models. Located in the “Heart of the Highlands,” the watershed contains the longest stretch of wild trout water remaining in the state and much of the watershed has been designated Category One in recognition of its support of the cold water fishery resource. In addition, the City of Newark owns 86 percent of the tributary area of the Watershed, which encompasses five active reservoirs with a combined capacity of over 14 billion gallons. This system provides potable water to more than 500,000 New Jersey citizens. The TMDL calculations using SSTEMP determined that low flows, primarily resulting from reservoir operation, and air temperature were the most important variables affecting in-stream water temperature. Given the two competing uses for the water in the system, implementation of the TMDL will attempt to find a balance that supports both uses. In the 2004 renewal of Newark's water allocation permit, the Department took steps in this direction by including passing flow requirements, a temperature action threshold of 65°F, and a requirement to assess operational options to attain temperature criteria and to determine the effect of operational alternatives on safe yield of the water supply system. The remaining identified sources of observed temperature impairment will be addressed through the application of other measures such as beaver management and reforestation of deficient riparian buffer areas.In New Jersey, numeric and narrative temperature standards are established to protect aquatic life designated uses based on stream classifications. Criteria are set forth wherein thermal alterations that would cause the temperature to exceed ambient temperatures by an established limit or to exceed a specified temperature maximum are prohibited.The Department's 2004 Integrated List of Waterbodies identified thirteen segments in the Watershed as being impaired for temperature. The Watershed contains approximately 153 total river miles, of which nearly 35 river miles are impaired as indicated by elevated temperature levels. More river miles are covered under the State's established TMDL than are actually listed due to the fact that New Jersey designs implementation plans to address entire watersheds, not just impaired waterbodies. Implementing a combination of BMPs and direct remedies of sources of heat added will provide restoration and/or protection from temperature impairment in nearly 23 percent of the Pequannock River Watershed.