Mohawk River Basin Water Quality

Science Center Objects

Elevated levels of nutrients (for example, phosphorus) in the Mohawk River can lead to eutrophication and potentially toxic blue-green algal blooms. The U.S. Geological Survey (USGS), in cooperation with the New York Department of Environmental Conservation (NYSDEC) collected nutrient samples and measured streamflow in the Mohawk River. These data are being used to develop a water-quality model that, in turn, will be used to develop a phosphorus TMDL (or Total Maximum Daily Load) for the river. Other water-quality data were also collected.

The New York State Dept. of Environmental Conservation (NYSDEC) has done a preliminary analysis of the Mohawk River and found elevated levels of nutrients in the water. Elevated levels of nutrients in the waters of the Mohawk River can lead to eutrophication and potentially toxic blue-green algal blooms. In a proactive approach to the problem, NYSDEC in cooperation with the US Geological Survey (USGS) collected a wide variety of water-quality samples from April to October 2016 at locations along the Mohawk River. 

These data were collected as the first step in assessing the condition of the river by determining concentrations of nutrients and other constituents to provide necessary data for the development and calibration of a water-quality model for the Mohawk River. The Clean Water Act of 1972 mandated that a plan should be put in place that limits the total maximum daily loads (TMDLs) for impaired surface-water bodies. A Total Maximum Daily Load refers to a calculation of the maximum amount of a pollutant that a water body can receive on a daily basis and still meet water-quality standards. TMDLs are implemented on a state by state basis. The USEPA has placed the responsibility of developing TMDLs and ambient water-quality standards for the waters of New York on the NYSDEC. Development of a TMDL for the Mohawk River is a multistep process and requires determining potential sources of the contaminants and quantifying the loads of contaminants entering the waterway. The second and third steps in the process is developing hydraulic and water-quality simulation models to estimate the flow volumes and contaminant loads along the river to simulate current conditions. Finally the calibrated models will be used to help in the development of a TMDL.

More information about Surface-water Quality in the Mohawk River Basin (Pilot RIBS/TMDL)

outline of Mohawk River qw sampling sites with multicolored dot locations

Mohawk River Water Quality Sampling Site Locations (Click here to see Interactive Map.)(Public domain.)

 

Water-Quality Sampling

 

man and woman in orange pfd suits using water sampler on river

Water-quality sampling on the Mohawk River near Latham, New York (Public domain.)

Thirty sites (interactive map, text list) were sampled throughout the Mohawk River Basin. Water samples were collected and analyzed for field parameters (including temperature, dissolved oxygen, pH, and specific conductivity), nutrients, suspended sediment, physical properties, minerals, unfiltered trace elements, filtered trace elements, organic carbon, phenols, and chlorophyll-a. At a few sites, carbonaceous biological oxygen demand (CBOD) samples were collected. Some water samples were tested for bacteria (fecal coliforms) and toxicity (Ceriodaphnia dubia).

 

 

 

 

 

 

Most samples were analyzed at the USGS New York Water Science Center Soil and Low Ionic Strength Water Quality Laboratory. Other labs included USGS National Water Quality Laboratory, USGS Kentucky Sediment Laboratory, USGS Wisconsin Mercury Laboratory, and a contract laboratories. 

 

 

 

 

 

 

 

 

2 men sitting on stone wall by Mohawk River with ADCP

Measuring discharge with an ADCP on the Mohawk River in Cohoes at the power plant diversion (Public domain.)

 

 

Discharge was measured at the time of sample collection to enable computation of loads. Discharge data from a USGS gaging station was used where available. Discharge at ungaged streams was measured using hydroacoustic technology and velocity-area methods. 

 

 

 

 

 

 

 

 

 

Surface-Water Modeling 

The USGS in cooperation with the NYSDEC will develop HEC-RAS hydraulic and water-quality models of the Mohawk River from near Rome to near Cohoes. The USGS will calibrate the hydraulic model using streamflow data from the network of streamgages in the Mohawk River basin. The water-quality model will be calibrated, by USGS, using water-quality and other data collected by the USGS, NYSDEC and other agencies.

Hydraulic Modeling will include: 

• Utilizing georeferenced data.

• Modeling culverts, bridges, weir structures, and gate-control structures.

• Modeling the connection between the river and the canal

• Setting boundary conditions

• Estimating roughness coefficients

• Simulating Wastewater Treatment Plant (WWTP) input volumes

• Calibrating the model using USGS (measured and estimated) streamflow data.

Water-Quality Modeling will include:

• Collecting Sediment and Biological Oxygen Demand.

• Compiling USGS, NYSDEC, WWTP, and other available water-quality data

• Designing water-quality model grid within the HEC-RAS hydraulics model domain

• Developing a water-temperature model using National Weather Service (NWS) meteorological data.

• Develop and calibrate a eutrophication model using the compiled water quality data.

 

woman with waders and big spoon standing knee deep in river

Sediment Oxygen Demand (SOD) sampling in the Mohawk River (Public domain.)