Instream Flow Program pilots real-time stream gage on North Branch River

NHDES’ Instream Flow Program’s goals are to determine, through scientific investigation, the seasonal flows necessary to support habitat for fish and river-side vegetation as well as human uses in the state’s designated rivers, and then maintain these protective flows during periods of low flow, such as during the recent drought. The Instream Flow Program currently compares real-time streamflow data provided by the US Geological Survey to each river’s protected instream flow values in order to determine when management actions are necessary. To date, protected instream flow values have been established for the lower Lamprey River and the Souhegan River, and are nearing completion for the Cold River. The Program continues to research the remainder of the state’s 19 designated rivers in order to determine their appropriate instream flows.

USGS gaging stations are not available at key locations along some of the state’s highest-priority designated rivers, however. Without real-time streamflow data, the Program cannot monitor protected instream flow values for these rivers, making it impossible to manage them in this important program. To address this challenge, the Instream Flow Program has been partnering with the US Geological Survey to reactivate former gaging stations or create new ones in order to eliminate these data gaps. In June 2021, the Instream Flow Program deployed its first automated water level station, which provides real-time streamflow data for a previously-inactive US Geological Survey gaging station on the North Branch River, a branch of the Contoocook River in Antrim.

The pilot station has been accurately and reliably providing streamflow data via a wireless uplink for four months, and the data are now available to the public via an online dashboard. The Instream Flow Program webpage summarizes the data and also includes a link to it. These data will enable the Program to monitor future protected instream flow values for the North Branch River, which is a major tributary of the designated Contoocook River and a protected river in its own right. The Program’s next real-time water level stations are planned to eliminate similar data gaps on the designated Piscataquog and Ammonoosuc rivers in 2022 and 2023, respectively.