Farmington River Flow Plan

Video - Managing Flow in the Farmington River

The purpose of this video is to provide additional detail about DEEP's management of flow on the Farmington River. Specifically, how managing the water stored behind the Colebrook River Lake Dam provides a unique opportunity to balance needs for fish, wildlife, recreation, river health, flood mitigation, tourism, hydropower, and safety by utilizing storage pools and achieving seasonal flow targets when possible. For additional information about DEEP's management of flow on the Farmington River, please see the text and links provided below.

Background

The Farmington River Flow Plan provides DEEP with options to modify the volume of water requested for release from Colebrook River Lake, Colebrook/Hartland, based on environmental conditions, such as surface flows monitored by the United States Geologic Survey (USGS), trends in precipitation data as published by the Connecticut Interagency Drought Workgroup, the pool elevation within Colebrook River Lake, and local/regional weather forecasts and conditions.

This plan, prepared for the Connecticut General Assembly's Environment Committee, outlines recommendations for managing water levels in Colebrook River Lake per Public Act 24-13. The primary goal of this plan is to lay out a strategy for optimal flow management on the Farmington River to balance needs for fish, wildlife, recreation, river health, flood mitigation, tourism, hydropower, and safety by utilizing storage pools and achieving seasonal flow targets when possible. Per authority provided in Public Act 24-13, as well as a letter sent to Department of Energy and Environmental Protection (DEEP) by the Metropolitan District Commission (MDC), DEEP will make requests to the US Army Corps of Engineers (ACOE) to release the water stored between elevations 644 feet to 701 feet in Colebrook River Lake to achieve the targeted releases.

Helpful links for additional information:

• The current status of Colebrook River Lake (inflow, outflow, elevation, flood control storage, etc) per the US ACOE webpage.
• USGS gage West Branch Farmington River at New Boston, MA (Inflow to Colebrook River Lake)
• USGS gage West Branch Farmington River at Riverton, CT (Outflow from West Branch Reservoir)  
• USGS gage Still River at Robertsville, CT (First major tributary below reservoirs)
• Drought Task Force web pages Connecticut or Massachusetts

Current Releases and Storage Volumes for Colebrook River Lake

Updated weekly or when flow release allocations change. Data as of December 22, 2025.

1. DEEP Action Category: DEEP uses the categories of surface river flow (much above normal, above normal, normal, below normal, much below normal), as published by the United States Geologic Survey (USGS) for stream gages in New Boston, Riverton, and Robertsville to inform water release decisions. In addition, DEEP follows trends in precipitation data (abnormally dry, moderate drought, severe drought, extreme drought, and exceptional drought), as published by the Connecticut Interagency Drought Workgroup, Massachusetts Drought Management Task Force, and the pool elevation within Colebrook River Lake to help inform water release decisions.
2. DEEP Target Release Value: Determined for each month and described in the plan, the value includes natural inflow up to 150 CFS (with a minimum of 50 CFS required of MDC at all times) and any release from the Otis Reservoir. Values are likely to be higher in times of excess water and lower in dry periods or drought.
   • 125 CFS during January, February, November, December
   • 150 CFS during March, April, October
   • 200 CFS during May, September
   • 250 CFS during June, July, August
3. Total Release: The sum of water being released by MDC(3a), DEEP(3b), Otis Reservoir(3c), and USACE(3d). MDC must release a minimum of 50 CFS at all times, any inflow up to 150 CFS, and all releases from Otis Reservoir. Note that releases to draw down the pool elevation in Otis Reservoir occur annually for several weeks starting in mid to late October. These increased inflows may bump the pool elevation within Colebrook River Lake temporarily (as the method to calculate inflow is based on the week prior to the current week) and are not "held" to refill the various storage pools.
4. DEEP Release Change From Prior Week: The change in the requested release from the prior week in CFS. 
5. DEEP Volume Remaining: The approximate amount of water remaining, in millions of gallons (MG), DEEP may use to implement the plan.
6. Cold Water Remaining: The approximate volume of cold water to support optimal trout habitat in million gallons (MG). Cold water, for this application, is defined as 20 degrees C (68 degrees F) or less. The volume is determined by DEEP Fisheries Division staff who measure water temperature and dissolved oxygen from the surface to the bottom approximately every three weeks from July to October. The volume of cold water remaining is an estimate and varies depending upon the release volume. Note: The data presented above is for storage in Colebrook River Lake, which is upstream of the West Branch Reservoir and as such there is often additional cold water being released regardless of CRL levels.
7. Days of Cold Water Remaining- this value is calculated by dividing the volume of cold water remaining by the millions of gallons of water per day being released (release CFS). This estimated value will vary either up or down depending upon the release flow (CFS). The estimated value also assumes that the volume of cold water is not being recharged throughout the summer.

Development of the Plan

• Recording of the public informational session held on January 22, 2025 passcode to view = ^qWJEQC1
• Presentation used in the public informational session
• Summary of stakeholder comments about the draft plan.

Questions about this draft plan may be sent via email to Mike.beauchene@ct.gov.

Content last updated on December 22, 2025