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The paper examines the proposed water temperature TMDL developed by the New Jersey Department of Environmental Protection for the Pequannock River watershed, and the implications for the five reservoirs in the watershed that serve as the primary source of drinking water for the City of Newark, New Jersey and surrounding communities. It discusses the modeling techniques used to analyze the water temperatures and shows how limitations of those models lead to unintended and unnecessary consequences for water supply.

In recent years, availability of sufficient water supplies in northern New Jersey has become an issue of concern not only for the water purveyors in the region, but also for the governmental agencies charged with overseeing those purveyors. Those concerns arise out of a series of relatively short-duration, but intense, droughts in the late 1990s and first few years of the current century. They are enhanced by a state development policy that focuses new growth in the existing urban and suburban areas of the state, which are found primarily in the northern part of the state. The paper summarizes these issues.

However, despite the urban and suburban character of much of northern New Jersey, that region also hosts some of the best recreational freshwater fisheries in the state. Among them, the Pequannock River watershed has the greatest stretch of native trout propagation and maintenance waters in New Jersey. Trout require specific environmental conditions, including appropriate water temperatures. The paper addresses the extent and significance of the recreational fishery.

The purpose of the proposed TMDL is to address exceedences of water temperature criteria intended to protect trout propagation and maintenance in various reaches of the watershed. The TMDL asserts that the main cause of the exceedences is the Newark reservoir system and it looks primarily to those reservoirs to manage water temperatures in the river. It uses several different models of water temperature in an attempt to understand how temperatures vary in the watershed and to support proposed changes in the operation of the Newark reservoirs to control water temperatures. The paper provides information on the basis for the water temperature criteria and the modeling.

The proposed TMDL fails to address the question of how the proposed changes might affect the availability of water in northern New Jersey, particularly in Newark and its surrounding communities. In addition, close examination of the models used in the TMDL discloses flawed logic that results in excessive reductions in available water. The paper provides details of the modeling performed in the TMDL, identifies the limitations and shows how those limitations lead to unnecessary reductions in available water for Newark. The paper shows how correct use of the TMDL models leads to very different conclusions regarding the causes of water temperature exceedences and how to manage them.

In addition, the New Jersey Department of Environmental Protection recently renewed Newark's water allocation permit for the five reservoirs and included requirements for operation of the reservoirs to control water temperatures in the watershed. Those requirements are not entirely consistent with the findings of the TMDL and lead to additional questions related to use of the Newark water supply reservoirs for control of water temperatures in the Pequannock watershed. Those inconsistencies are discussed in the paper.

In summary, the paper illustrates how TMDL development may have ramifications well beyond the specific issue being addressed (water temperatures suitable to trout, in this case), and how attempts to address environmental impacts through the TMDL process can sometimes have unintended environmental impacts of their own (unnecessarily large reductions in availability of water supply, in this case).

Document Type: Research Article


Publication date: 2005-01-01

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