Progress / Science

Friends of the Mad River Examines 25 years of Water Quality Data

Since 1985, the Friends of the Mad River (FMR) has, through the collection and analysis of water samples, monitored water quality conditions throughout the Mad River watershed to identify, assess and take action to correct water quality problems. The water quality data gathered from monitoring are perhaps unparalleled in Vermont, especially in terms of the length of the record (31 years) and the consistent and repeated sampling of the same sites throughout this time period. With grant funding arising from a 2015 Watershed Grant issued by Vermont Department of Fish and Wildlife, FMR was able to conduct a comprehensive review and recently released the results of its analysis of certain data collected through this program identifying several areas and issues of concern as well as providing recommendations for future monitoring efforts.

Starting in 1985 and continuing through 2015, staff and volunteers from FMR used portable field equipment and an in-house laboratory to quantify various physical, chemical, and biological parameters at a total of 57 sites along the Mad River and its tributaries (only 18-40 sites were sampled in any one year). Starting in 2006, the Friends of the Mad River partnered with the LaRosa Analytical Laboratory of the Vermont Department of Environmental Conservation to measure total phosphorus, turbidity, and Escherichia coli (E. coli) at a subset of those 57 sites (E. coli bacteria was only analyzed through this partnership between 2006-2011). A summary of findings is provided below.

Water temperature was measured at 52 sites on 143 dates between 1988-2014. Water temperatures along the main stem and tributaries were generally high, primarily because these measurements were recorded during the summer months (June-August). Water temperatures were highest in the middle and lower reaches of the main stem and were lowest along the upper reaches of the main stem and many of the tributaries. Higher temperatures likely reflected the more open land uses, lack of vegetative cover, and more meandering river channel along the lower reaches of the main stem.

Caption: Looking downstream along the Mad River just downstream of the village of Moretown on October 15, 2015. Note the large bedrock outcrops and sand and gravel bars, both characteristic of this dynamic river system. The pools among the distant rock outcrops are one of many popular swimming areas along the Mad River. Photo credit: Fritz Gerhardt, Beck Pond, LLC.

Looking downstream along the Mad River just downstream of the village of Moretown on October 15, 2015. Note the large bedrock outcrops and sand and gravel bars, both characteristic of this dynamic river system. The pools among the distant rock outcrops are one of many popular swimming areas along the Mad River. Photo credit: Fritz Gerhardt, Beck Pond, LLC.

Total phosphorus, which measures the concentration of all forms of phosphorus in the water column and is an important measure of nutrient levels in rivers and streams, was measured at 19 sites on 55 dates between 2006-2015 (18 sites were sampled ten years). Total phosphorus (TP) concentrations were remarkably low across almost all of the sample sites. The only areas of concern having elevated TP concentrations were along two tributaries (High Bridge and Folsom Brooks) and the main stem in the vicinity of Moretown village. At two of these three sites, TP concentrations have increased over time and the positive relationships with stream flow suggest that much of the phosphorus at these two sites may be originating from nonpoint sources, such as surface runoff from agricultural and other land uses and from unpaved roads, especially along High Bridge Brook.

Turbidity, which is one way to measure the clarity of water, was measured at the same 19 sites on 55 dates between 2006-2015 (18 sites were again sampled ten years). Turbidity levels were also remarkably low across all sample sites. Turbidity levels were slightly higher at two sites located along the main stem near the villages of Moretown and Waitsfield, especially during the two most recent years (2014 and 2015). At a third site along High Bridge Brook, turbidity levels were also slightly higher than elsewhere and there the turbidity levels had increased markedly, especially during the past five years.

Fecal coliform and Escherichia coli (E. coli), which are two types of bacteria found in the intestinal tracts of humans, pets, livestock and other warm blooded animals, are valuable indicators of the health and safety of surface waters, especially in areas valued for swimming. Fecal coliform bacteria were measured at 56 sites on 59 dates between 1985-1991 and 2002-2005 (18-39 sites were sampled in any one year), and Escherichia coli were measured at 47 sites on 83 dates during the 2002-2015 period (36-39 sites were sampled in any one year). Both fecal coliform and E. coli counts were very high at a number of sites along the lower section of the main stem as well as along several tributaries. Both fecal coliform and E. coli counts increased consistently from upstream to downstream areas along the main stem and were markedly higher from the village of Waitsfield downstream to the mouth of the Mad River. At several of the downstream sites, E. coli counts also showed a trend towards higher values during the past 10-15 years. The positive relationship between E. coli and stream flow at many of these sites suggested that the source(s) of the E. coli can be related to rainfall and land runoff.

Collectively, the analysis of 25 years of data gathered through water quality monitoring greatly increased FMR’s understanding of water quality problems and threats in the Mad River watershed. In general, water quality conditions in the Mad River and its tributaries were very good to excellent; however, a few areas exhibited levels of TP, turbidity or E. coli that were higher than desirable. In order to maintain this outstanding long-term data set and to further pinpoint and assess the sources of these water quality problems and threats, FMR recommends monitoring continue into the future and some new sampling locations be added. Better understanding of water quality conditions will facilitate efforts to identify and develop the appropriate protection and restoration strategies that will most effectively protect and improve water quality throughout the Mad River watershed.