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Water Quality

Protection and improvement of water quality in the Mohawk River watershed is necessary so that people are protected from health hazards, drinking water supplies are conserved, aquatic communities can flourish and natural processes are sustained.  Water quality monitoring in the Mohawk River Basin has been conducted since the early 1970’s as part of the DEC’s statewide ambient water quality monitoring program. Surface water quality is assessed by means of chemical, biological, and physical parameters. Water quality assessment can identify which contaminants are present, their sources, and the extent to which they affect the health of the watershed. Although many of the sub-watersheds of the basin have been monitored through this program, there are still significant numbers of un-assessed streams, rivers, and lakes. 

The headwaters of the Mohawk River are located in the southwestern corner of the Adirondacks. In this area, acid precipitation, combined with low buffering capacity of the waters, increases the availability of some contaminants, such as aluminum and mercury, as well as producing low pH waters.  While the transport of sediment is a natural process associated with the evolution of river systems, land use and human activities such as agriculture, residential and commercial development, increasing impervious surface cover, removal of vegetation along riparian buffers, and poor road ditch, bridge, and culvert design can dramatically increase the amount of sediment being transported. Too much sediment has a detrimental impact on the ecological health of a river by limiting light penetration, reducing the viability of aquatic organisms and impacting the more pristine waters downstream. Bedload sediment clogs the mouths of tributaries as well as receiving waters in the Mohawk main stem, necessitating dredging to maintain channel conveyance and navigation depths. The U.S. Geological Survey (USGS) has been periodically collecting suspended sediment data from the mouth of the Mohawk since the mid-1950s. Its data indicate the Mohawk annually exports on the order of 500,000 metric tons of suspended sediment. A recent 4-year study by the USGS indicated the yield of suspended sediment from the Mohawk watershed was 2.8 times that of the Upper Hudson (48.3 versus 17.3 metric tons/km2) just above its confluence with the Mohawk. 

Warmer water temperatures and increased weather extremes associated with climate change are expected to lead to greater intensity and duration of stratification, nutrient loading, turbidity and eutrophication.  These conditions will increase the risk of harmful algal blooms and could affect drinking water quality and function of wastewater treatment plants.