MONITORING WATER-QUALITY IN THE CONNECTICUT RIVER WATERSHED HEADWATERS TO LONG ISLAND SOUND

The U.S. Geological Survey (USGS) has been developing a group of studies that are focused on collecting data to improve understanding of the magnitude and timing of nitrogen and carbon transport to Long Island Sound (LIS). Several different cooperative and federal projects overlapping in time have created a scenario of contemporaneous data collection efforts that extend over the entire length of the Connecticut River watershed from the headwaters in northern Vermont and New Hampshire to Long Island Sound (LIS). USGS in cooperation with several federal and state agencies are currently monitoring and assessing nutrient loads throughout the entire the Connecticut River watershed from the headwaters to the mouth of the river and into Long Island Sound (LIS).

Monitoring includes continuous streamflow, discrete samples for nutrients and carbon analysis, high flow-event samples, and continuous water-quality monitoring at selected sites. Twenty-six stream sites in the Connecticut River watershed including nine sites on the mainstem of the Connecticut River and seventeen important tributaries are being sampled monthly for nutrient and carbon analysis. These data will be used to estimate loads of nutrients and carbon for the entire Connecticut River watershed and provide important information on the relative contribution by subbasins within the watershed. Continuous water-quality monitoring is being conducted at four sites along the Connecticut River mainstem, with additional sites being installed in 2024. Continuous water-quality monitoring includes water temperature, specific conductance, dissolved oxygen, turbidity and at some sites chlorophyll a, nitrate, and fluorescent dissolved organic matter (fDOM). Data from the continuous monitoring at these sites has been used to document, in real-time, pulses of turbidity, fDOM, and nitrate from storm events or seasonal influences through the Connecticut River to LIS. The presentation will include a description of the study designs of concurrent projects that are collecting field data and how the data from this work is being used to assess point and non-point source contributions in the Connecticut River Watershed to help inform management decisions.