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New Hampshire Department of Environmental Services

Photo of North River in Lamprey River Watershed

Welcome to our web pages for information on the progress of instream flow protection projects.

Souhegan River ~ Lamprey River

The Instream Flow Program is developing river-specific numerical criteria for stream flow protection and water management plans to implement those criteria. This site documents the history and current status of the program.

Instream Flow Program calculates the stream flows that protect fish, recreation and stream bank species. The program then develops management plans to protect instream flows and ensure the water availability for off-stream uses. The management plans describe conservation, water use and dam management actions to apply during extended low-flow and drought conditions.

The Instream Flow Pilot Program develops river-specific numerical criteria for instream flow protection. Actions needed to meet these criteria direct the water management plans. 

Instream Flow protection under RSA 483

The New Hampshire Legislature created the Instream Flow Program in 1990. Then, in 2002, a broad coalition of New Hampshire business and conservation interests joined together to enact compromise legislation that called for in-depth pilot study on the Lamprey River and Souhegan River to determine how best to protect flows on the state’s Designated Rivers.

With the advice and input of the statewide Rivers Management Advisory Committee (RMAC), NHDES adopted Instream Flow Pilot Rules (Env-Wq 1900) that applied to the Souhegan and Lamprey Rivers. The rules described the process for conducting a Protected Instream Flow study to quantify stream flow standards and for developing a Water Management Plan to attain those standards.

The pilot results and recommendations were reported to the legislature December 2015. As a result new legislation was adopted and the Instream Flow Program was instructed to develop new rules to apply instream flow protections to the rest of the Designated Rivers of the state.

Instream Flow Rules

The new rules are under development. NHDES has developed discussion documents for review prior to going to rulemaking. These discussion papers and meeting documents are available at the Rivers Management Advisory Committee blog at

NH Department of Environmental Services | 29 Hazen Drive | PO Box 95 | Concord, NH 03302-0095
(603) 271-3503 | TDD Access: Relay NH 1-800-735-2964 | Hours: M-F, 8am-4pm

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