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Stoney Creek is a water supply watershed and is designated for contact and non-contact recreational uses such as swimming, fishing, and boating. The Town uses Stoney Creek for their drinking water. The Town wastewater treatment plant (WWTP) is also permitted to discharge secondary treated effluent directly to the creek. In the early 1980s, local fisherman began to notice and report a steady decline in the recreational fishery. By the late 1980s, the community became concerned that water quality was declining in the creek due to the WWTP discharges as well as nonpoint sources of pollution. The major nonpoint source inputs were thought to be from runoff; rapid development was converting the watershed from primarily forested lands to residential and commercial land uses.

Setting Goals and Objectives

The first step to the watershed monitoring study was to develop and refine objectives. The association agreed that the primary objective was to characterize water quality conditions and improve the recreational fishery. With limited resources, the association began their study by collecting any available historical data related to land use/land cover, population growth, waste water discharges, WWTP upgrades, and stream quality. Unfortunately, the in-stream water quality data were limited to a couple of stream sites occasionally monitored by the WWTP as part of its NPDES permit. Extensive and detailed land use information, however, was available from the Town Planning Department as part of a geographic information system (GIS). The GIS was first used to delineate the watershed boundary so that the association could easily determine the spatial scope of the study. Using this GIS database, the association was able to create detailed maps of land use/land cover in the watershed and changes over time. Once the historical land use/land cover changes were better understood, the next step was to determine the effects to the creek by designing a water quality monitoring program.

Sampling Design

Based on the potential nonpoint source inputs caused by development throughout the watershed and the WWTP point source input, the Association decided to utilize a stratified random sampling approach. The effect of the WWTP was a special interest of the study, so sample sites were selected immediately upstream and downstream of the facility. These stations also matched the WWTP stream sites previously monitored, allowing for direct comparison of study data and historical data. The remaining sampling stations were selected at random, stratified by the upstream and downstream portions of the watershed. A great advantage of using a random sampling design is that statisticians have developed procedures for calculating confidence intervals for the estimates. For example, we do not know with certainty whether an individual water quality measurement is representative of the creek as a whole. The confidence intervals are affected by sample size and natural variability of the data. For repeated sampling, however, we could calculate a confidence interval (e.g. 90% confidence interval) that any parameter measurement would fall within that percentage of the time, thus illustrating the probable range of water quality conditions. After evaluating the statistical considerations, available funding, and site accessibility and safety.

Implementing the Monitoring Program

Because the Association lacked the expertise to conduct an extensive sampling effort, they contracted the services of an experienced environmental consulting firm. The consulting team assisted in sample design, parameter selection, equipment procurement, and training in proper QA/QC procedures in accordance with state and federal regulations. Laboratory costs were minimized by establishing an agreement with the local water and sewer authority's certified laboratory. The consulting firm suggested a monitoring program designed to collect both dry- and wet-weather stream samples. This approach provides a clearer picture of the relative pollutant contributions of continuous point source inputs and episodic nonpoint source impacts. The dry weather samples were collected monthly. Manual grab samples were collected, stored on ice, and sent to the water treatment plant for laboratory analyses. These analyses included nutrients (nitrogen and phosphorus), coliform bacteria, suspended solids, and some metals (lead, zinc, and cadmium). Field measurements of pH, dissolved oxygen, conductivity, and temperature were recorded at each sampling station using a multi-parameter water quality meter. Due to the difficulties of collecting wet-weather samples, composite samples were collected manually only five or six times a year. Flow measurements were also recorded for each sampling event by developing stage discharge relationships (rating curves) at each site and installing stream gauges. The flow data were crucial for calculating the relative loading rates of pollutants during dry weather flows versus runoff events. Because the initial concern and objective of the program was to evaluate the recreational fishery, the study also collected biological and habitat information. Benthic macroinvertebrate samples, fish samples, and riparian and stream channel habitat assessments were used to evaluate biological health and habitat quality.

Data Management

The data collected for the Stoney Creek Watershed Monitoring Program were maintained in a computer database. Using database and spreadsheet tools, the data were statistically analyzed and routinely interpreted. For each water quality parameter, statistical indicators such as means, medians, minimum values, maximum values, variances, and 90 percent confidence intervals were calculated. Statistical analyses were an important step in determining if water quality criteria had been exceeded or if water quality was significantly degraded. As the program has progressed and the number of measurements maintained in the database has increased, trends in quality have also been calculated and presented to the members and the public in easy-to-understand graphics and quarterly newsletters.

Program Evaluation

Currently, the Association is focusing their efforts on reducing nutrients from the WWTP effluent and from nonpoint sources throughout the watershed. Hydrological changes (e.g., increased wet weather flow rates resulting from increased impervious land area and runoff) and erosion and sedimentation impacts caused by development in the watershed have also contributed to the decline in the fishery and the quality of stream habitat. Watershed managers are utilizing the monitoring information to target resources and management strategies. For example, data collected in the early stages of the program were used to make informed decisions about the best ways to protect and improve the resource while minimizing costs to the community. The data resulted in the design and implementation of a variety of measures, including:

• improved development ordinance aimed at reducing water quality impacts
• improved erosion and sedimentation control requirements
• requirements for urban best management practices (BMPs)
• stream and habitat restoration projects
• minimum stream buffer requirements
• education and conservation programs

Water quality data are also being used to develop a water quality model. The model is an important tool used to predict the impacts of continued development and the effects of different management strategies. Together, the monitoring program and model can be used to develop and evaluate the best and most cost-effective water quality protection measures. To date, the successes of the program are a testament to the initiative and hard work of concerned citizens, local anglers, Town staff, and the Association members. Because the Association is committed to achieving the objectives of the program, the good news for Stoney Creek is likely to continue.