Stream Connectivity Monitoring
Stream connectivity is important for the ecological health of the stream and downstream waters. The Water Monitoring and Assessment Program defines stream connectivity as the hydrologically connected pools and riffles that link stream habitat along a longitudinal continuum (upstream to downstream), while also recognizing the lateral dimension (connection to flood plain) and vertical connection to groundwater. Disconnected stream connectivity includes streams that are completely dry, only have pools of standing water, or have very minimal flow in which some pools and riffles are disconnected. Connected streams includes flowing bodies of water in which the pools and riffles are well connected. There are thousands of man-made structures (i.e. dams, culverts, surface and groundwater withdrawal locations) in Connecticut which negatively impact stream connectivity and can result in aquatic habitat fragmentation.
Program Development
Beginning in 2016, the Water Monitoring and Assessment Program in collaboration with the Water Quantity Program developed a cost-effective technique using trail cameras to better assess human alteration to stream connectivity. This involves taking hourly images of streams and categorizing them into six stream connectivity categories that relate flow and habitat availability to biological processes in streams. Once a series of site images are categorized, metrics are calculated to describe the magnitude, frequency, duration, and timing components of stream connectivity. This information is used to identify alterations in stream connectivity and inform stream management activities.
The data is used to categorize and quantify stream flow impairments for the Integrated Water Quality Report. From 2016 to 2020, 55 stream segments were monitored with over 500,000 images. Over the same time period, we increased the stream miles identified as impaired for flow alteration from 34 stream miles to 159 stream miles. We are also using the information generated by this project to support the CT State Water Plan, Water Diversion Permitting Program, and implementation of the Stream Flow Regulations.
Current Monitoring Efforts
The Water Monitoring and Assessment Program continues to monitor stream connectivity with trail cameras throughout Connecticut. Typically, about 30-40 trail cameras are deployed each year. The streams that are monitored include streams that are near USGS stream gages, headwater streams, streams that are downstream of dams required to make stream flow releases in accordance with the Stream Flow Standards and Regulations, streams that could be impacted by groundwater diversions, and other streams with specific monitoring goals.
The Water Monitoring and Assessment Program continues to further this program by participating in a national work group partnering with USGS and US EPA as part of the Flow Photo Explorer Project. The goal of this project is to develop new approaches for collecting hydrologic data in streams, lakes, and other water bodies, especially in places where traditional monitoring methods and technologies are not feasible or cost-prohibitive. The Water Monitoring and Assessment Program also collaborates with Connecticut College on a project to improve image processing and analysis. The goal of these projects is to develop new approaches for collecting and analyzing hydrologic and stream connectivity data using automated processes.
Reports and Publications
Monitoring Stream Connectivity with Trail Cameras Project Summary 2016 - 2020
For More Information Contact:
Melissa Czarnowski
Stream Connectivity Monitoring Project Lead
Content last updated June 3, 2025