New Jersey Water Science Center
Great Falls of the Passaic River at Paterson, N.J.
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Delaware Water Gap NPS
Project Title: NJ199 Delaware Water Gap NPS
This project will provide baseline data and an understanding of water-quality in streams entering the Delaware Water Gap NRA. Specific project objectives include: · Collect water quality data in 14 watersheds entering the Delaware Water Gap NRA over a 2-year period, · Provide an overall assessment of the current and potential effects of development on long-term and episodic water quality in streams, and · Evaluate all data collected to develop a cost effective strategy for future monitoring.
Statement of Problem
Water quality at DEWA is monitored by a number of agencies in this multi-state region. This includes County (Pike and Monroe), State (PA, NJ, and NY), DRBC, and Park Service programs. These programs incorporate varying sampling strategies that are often not comparable with each other. For instance nutrient data may be incompatible because different analytes are measured (for example, total nitrate vs nitrate+nitrite) and different methods have variable reporting limits. Also, high detection limits for phosphorus and other compounds have limited the parks ability to measure existing water quality. In addition, the sampling frequency (4 times per year at most) and limited number of streams sampled has been inadequate for developing standards. Because of these conflicting authorities, priorities, and analytical procedures available data cannot be used to either define "existing water quality" or to detect "measurable change" as the Special Protection Waters Regulations intended.
The primary threat to water quality and ecologic communities in the DEWA region is residential development. The five counties surrounding DEWA have experienced some of the most rapid residential development in the United States during the past several decades (250 percent growth during the period 1970 to 1990). Pike County (PA) has been the fastest growing county in Pennsylvania since 1970. Recent estimates indicate local populations have grown by more than 50 percent since 1990. Furthermore, these census figures do not include the continuing proliferation of vacation homes in the area, because they are not "primary residences" The human population in many area developments is three to six times greater during summer weekends and holidays than during the winter. For example, the year-round resident population of one such development (Hemlock Farms) is about 2,500, but on summer weekends this population swells to over 10,000.
Strategy and Approach
Water quality samples will be collected and stream discharge measurements will be made at 14 stream Boundary Control Points to be selected by the NPS in consultation with the USGS. Stream sites will be selected based on their priority to the Park, to represent a range of development conditions, and based on their suitability for water-quality sampling and stream-flow measurement. The study will focus on nutrients in the streams since these are perceived to be the most likely cause of impairment at present. Ions that are indicators of human impacts (boron and chloride) and indicators of acid-rain impacts, (nitrate, sulfate, and calcium) will also be sampled. Some microbial sampling will also be conducted. Nutrient sampling will be conducted at least 12 times per year at each site and select ions and suspended sediment will be sampled at least 4 times per year at each site. Sampling and discharge measurements will be conducted over a range of flow conditions during three critical periods of the year: (1) early spring runoff (March) - before algal primary production reduces stream nutrient concentrations, and before the vacation peak; (2) summer base flows (July-August) - during the vacation peak; and (3) early fall base flow (October) - after the vacation peak, but before tree leaf drop and subsequent increased algal primary production. Biweekly sampling will be conducted during the summer and each site will be targeted for at least one storm sample per summer. Storm samples will be analyzed for nutrients, ions, and suspended sediment.