Water Quality | A Look at the Water Quality of the Eightmile River, CT

At the time of designation, 92% of all of the Eightmile watershed’s rivers and streams and 99% of all the watershed’s groundwater meets the CT standards for Class A (or better) water quality classifications. This high water quality is one of the outstanding values for which the Eightmile watershed was designated. The Eightmile continues to cultivate and deepen partnerships with local organizations working toward achieving and maintaining high water quality in the watershed. To monitor and maintain this high quality, the Committee is working on a number of water quality monitoring initiatives that emphasize a watershed approach to management. “River management isn’t successful unless the whole watershed is healthy,” explains Anthony Irving, the Eightmile River Wild and Scenic Coordinating Committee Chair.

To establish baseline information, eleven streams are monitored every summer in the watershed for ten weeks using handheld instruments. Conductivity, temperature, pH, total dissolved solids, salinity, and dissolved oxygen are all measured at the same time and day each week. Current surveys will continue through 2025.

To further understand the watershed, USGS gauging stations have been established to continuously monitor streamflow information year-round.

In addition, temperature loggers were deployed in conjunction with the CT DEEP, and data were used to update a map of the thermal class of streams in the watershed (as cold, cool or warm). Data collection from these loggers is ongoing, and allow for temperature monitoring during the warmest months of the year when warm water can have a negative impact on fish and other aquatic life, including native brook trout.

Water quality monitoring map provided by the Eightmile River Wild and Scenic Coordinating Committee.

Road salt is a growing concern in the watershed, and high conductivity levels are being seen in some stream segments throughout Connecticut. High salinity levels are being seen in the summer in the Eightmile watershed, indicating that it’s not just a winter flush, but that groundwater may have high salt levels as well. With salt as a growing concern, a National Park Foundation grant provided the opportunity to do sampling for conductivity with the goal of gaining a better understanding of how salt is impacting our local streams and groundwater. Eight conductivity loggers remain in streams year-round recording measurements every hour.

RBV macroinvertebrate assessment photo courtesy of the Eightmile River Wild and Scenic Watershed Facebook page.

For over 15 years, Riffle Bioassessments by Volunteers (RBV) have been conducted on stream benthic macroinvertebrates to see if streams in the Eightmile watershed are meeting "aquatic life support goals" for habitat. Certain macroinvertebrates are considered indicators of high water quality, while other species are more tolerant of poorer conditions. Through the collection and identification of benthic macroinvertebrates, the water quality and stream habitats are assessed. Over thirty sites in the watershed have been sampled! The Committee was able to establish that many more segments are meeting Connecticut’s aquatic life goals. Not only did sampling collect valuable data on the macroinvertebrates in the watershed, but the Riffle Bioassessments by Volunteers (RBV) Field Experiences provided the following quotes that demonstrate the success of the events:

• Alivia, age 10 said “It was so much fun, and I learned so much! I had no idea that there were so many bugs living deep in the water like that and that they help tell us if the water is clean.”

• Avary, age 8 said “I loved learning about trees, pines, glaciers and how the land around us was formed. It was fun to collect the tiny bugs and sort them out.”

• Emily, age 10 said “I had so much fun I felt like a real scientist, studying all the bugs was so cool I knew there was bugs in the water I just didn’t know that there was so many different species.”

• Kaitlyn, age 13 said “I loved the program! I learned so many interesting facts and history of the land and waters around us. It gave me a new perspective when hiking in CT, knowing how the land was formed. Collecting and sorting the bugs and data was fun, made me feel like a real scientist out in the field!”

• Liz, mother, said “Thank you so much for an awesome adventure today! We all loved it!”

• Karianne, mother, said “Thanks for a fun, educational afternoon!”
  

More information may be found in the Newsletters on the Eightmile webpage.

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