Fall 2015 River Flows at Historical Lows

As the year comes to a close, the Pomperaug River Watershed Coalition (PRWC) reports that river flows within the 90 square mile Pomperaug Watershed were at record lows during extended periods this Fall. Flows in the three major tributary rivers - the Pomperaug, Nonnewaug and the Weekeepeemee- were at or near historical lows when compared to 81 years of U.S. Geological Survey (USGS) flow data.

From January through November, the Town of Southbury typically receives an average of 47.12 inches of rainfall measured as both rain and a snow equivalent. Rainfall total for the same period in 2015 was 30.70 inches, nearly a 35% reduction in precipitation. This deficiency in rainfall not only impacts river flows but also has an adverse effect on groundwater, the source of both public utility and private well drinking water within the Pomperaug Watershed. The USGS groundwater monitoring station in Southbury indicated that just prior to the end of October there was a steady decline in groundwater levels approaching those of the 2010 drought.

Research conducted by USGS in collaboration with PRWC demonstrates that groundwater provides between 60 and 70 percent of flow in the Pomperaug River. A computer based modeling study completed by the University of Massachusetts’ Northeast Habitat Program with support from PRWC and the CT Department of Energy and Environmental Protection (DEEP) has established the river flow values needed to properly support aquatic health within the three major tributaries noted above. The September and October low river flows demonstrate that rivers were not supporting the critical flows needed for a healthy river habitat. In fact, sections of the Weekeepeemee River had dry river beds and the Pomperaug River was flowing only at a rate of 15% of the critical flow requirement. DEEP officials confirmed that they would expect fish mortality to increase significantly during such conditions.

Commenting on the impact that the stressed water resources have on the region, PRWC’s executive director, Len DeJong states that “the critically low river flows and diminished groundwater supplies witnessed in 2015 underscore the importance of informed and proactive plans to balance the management of our water resources to meet the health, economic, environmental and recreational goals of the watershed communities. PRWC will continue to advocate on behalf of those water resources.”

PRWC will further its work with its coalition partners including community officials, public water suppliers, DEEP and the CT Department of Public Health and the Pomperaug Health District along with statewide river protection environmental associations in an effort to provide for planning safeguards to better protect against the impact of drought and the allocation of water resources within the Pomperaug Watershed. Such work includes: proactively planning for, monitoring and analyzing the impact on the transfer of water to the planned Towantic power facility and other water withdrawals; facilitating further discussion on municipal drought ordinances; continuing to perform macro invertebrate studies; and collecting river temperature data along with completing updates to local watershed management plans with a focus on correcting river impairments. Furthermore, as an active participant in the ongoing development of Connecticut’s first State Water Plan, PRWC will continue to share it research and data in anticipation that both the Plan and subsequent legislation and regulation will strengthen the protection of local water resources.

PRWC reminds water users throughout the watershed that their conservation practices do have a significant impact on lowering water demands. Replacing water use fixtures with high efficiency Energy Star-rated units, repairing water leaks, and washing only full loads of dishes and clothes are just a few of the many water conservation practices recommended. Information on these and other suggested ways to conserve water are available from the region’s local public water suppliers and can also be located on PRWC’s website on the Resources page.