DEVELOPING A USE ATTAINABILITY ANALYSIS FOR AN URBANIZED WATERBODY

The New York City Department of Environmental Protection (DEP) is conducting a multi-phase program to address the impacts of combined sewer overflows (CSOs), wastewater treatment plants, and other pollutant sources on New York Harbor waterbodies as part of its continuing efforts to maintain and improve water quality in the Harbor and its tributaries. A watershedbased approach is being utilized to conduct an integrated evaluation of the interdependent factors affecting receiving water uses, including point and non-point sources, upland and shoreline uses, habitat, sediment, and water quality with the active participation of stakeholders. Total Maximum Daily Load (TMDL), CSO policies, regional planning, and other regulatory issues are being addressed simultaneously by the DEP, which has conducted comprehensive planning to address these issues for one particular TMDL-listed waterbody, Paerdegat Basin. A comprehensive plan for the waterbody is being implemented while regulatory processes are being navigated.Paerdegat Basin is an urbanized estuarine tributary of New York Harbor with CSO discharges. Water quality conditions do not meet the numerical and narrative water quality standards of its use designation at all times. The waterbody fails to meet water quality standards by exhibiting high levels of coliform bacteria, low levels of dissolved oxygen, visible floatables, and other aesthetic impairments. Paerdegat Basin is listed on New York State's 2002 303(d) list requiring TMDL development. A comprehensive plan has been developed that includes CSO abatement, waterbody and riparian improvements. The plan addresses evolving regulatory processes such as the U.S. Environmental Protection Agency's new marine dissolved oxygen criteria, long-term CSO planning, and TMDL development. With its resulting water quality improvements, the plan is expected to benefit Paerdegat Basin's aquatic community, improve recreational opportunities such as boating and fishing, and enhance waterbody aesthetics to conditions consistent with desired waterbody and riparian uses. However, the planning process, which included TMDL development within a knee-of-the-curve approach, indicated that the plan would not fully achieve designated narrative and numerical water quality standards. Following EPA's 2001 guidance for Coordinating CSO Long-Term Planning With Water Quality Standards Reviews, it was determined that existing designated uses may not be reasonably attainable and therefore a water quality standards review was conducted and information required to support a Use Attainability Analyses (UAA) for Paerdegat Basin was developed.The physical, chemical and biological factors affecting use attainability were explored following EPA's UAA guidance. A state-of-the-science approach was utilized to address fish and aquatic life protection, recreation, and aesthetic uses for Paerdegat Basin. The analysis indicated that the high level of urbanization that has occurred in the Paerdegat Basin drainage area in particular, and in New York City in general, with attendant intense population density, and the paved surfaces and roadways that necessarily follow causing large volumes of runoff, will have some level of adverse impact on what is, in essence, an artificially constructed drainage channel. Hydrologic and human-caused conditions that are not feasible to restore represent limitations on assuring attainment of fishable/swimmable conditions at all times. The analysis further indicated that the DEP's plan will significantly improve water quality and ecological conditions but not completely eliminate impacts and therefore a UAA is appropriate. The resulting restored water uses of the plan, however, are entirely consistent with, and supportive of, reasonable best uses of Paerdegat Basin and are also consistent with stakeholder goals.