Water quality monitoring at Weir Farm National Historic Site: Northeast Temperate Network 2014 summary report

Gawley, William; Dieffenbach, Fred

This report on the water quality of Weir Farm National Historic Site (WEFA) includes data gathered by the Northeast Temperate Network (NETN) in the 2014 monitoring season and displays these results in graphic form, accompanied by a brief interpretation. The data address the NETN objective to detect change in the status of physical, chemical, or biological attributes of park freshwater bodies. The NETN Freshwater Monitoring Protocol calls for one pond at WEFA to be sampled monthly from May through October. Staff measured physical and in-situ water chemistry parameters each month and periodically collected water samples for analysis at the University of Maine’s Sawyer Environmental Chemistry Research Laboratory. Monthly sampling parameters included in-situ water quality measures (pH, specific conductance, temperature, and dissolved oxygen), light penetration, weather, and stage. In May and August, water samples were obtained and analyzed for acid neutralizing capacity (ANC), color, nutrients, dissolved organic carbon (DOC), chloride, sulfate, and chlorophyll a. In general, most 2014 water quality parameters for Weir Pond in Weir Farm National Historic Site were within state standards, and were above the EPA Ecoregion 14 criteria, where applicable. Several metrics showed a great deal of variability relative to their respective historic range, and where variability was least the measures were frequently biased toward one end of the range. Specific conductance measurements were all at the high end of the historic range, with only one measurement being below the 90th percentile. pH varied throughout the entire historical range, with two readings exceeding the high state standard. Temperature and dissolved oxygen were similarly variable throughout the sampling season. Both spring and summer chloride values were among the highest recorded by the NETN to date. Most of the remaining metrics were not as variable, and fell within their historic ranges. Spring (June) total phosphorus levels were nearly double those of the August samples, and were likely responsible for high spring chlorophyll a concentrations in the pond, which may have been an indication of a small to moderate algal bloom.

Water quality monitoring at Weir Farm National Historic Site: Northeast Temperate Network 2014 summary report

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