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New Hampshire Department of Environmental Services

Souhegan River

A water management plan designed to maintain the river’s protected instream flows is in place for the Souhegan River. The water management plan was developed as the second part of the Instream Flow Program’s work to conduct a study to determine stream flow requirements for each Designated River and then to develop and employ management plans to maintain those stream flow requirements.

The project to develop a study process and the water management plan consists of 12 tasks. The protected instream flow study was completed in tasks 1 through 7 resulting in a final report containing the final recommendations for protected instream flows. Upon completion of the study, the NHDES commissioner approved the protected instream flows described in the report with the Commissioner’s Declaration of the Establishment of Protected Instream Flows for the Souhegan Designated River.

The water management plan was developed with water users, dam owners, and other interest groups. In tasks 8 through 12, the management needs for stream flows were calculated, and the management alternatives were evaluated and selected. Management actions include water use management and conservation plans for affected water users, and dam management operations by affected dam owners. Management actions are taken after stream flows fall under defined thresholds for extended durations of time. The water management plan documents each water user or dam owners’ management actions.

NHDES has developed an assessment tool to determine when management actions should be applied. The assessment tool (under Current Instream Flow Conditions below) tracks the daily stream flows and describes conditions with respect to the protected instream flow criteria.

Souhegan River Watershed Map

Protected Instream Flow Study
Souhegan Protected Flows Established April 1, 2008, Amended August 30, 2013

Water Management Plan
Souhegan Water Management Plan established August 30, 2013

Current upper Souhegan Instream Flow Conditions Microsoft Excel Symbol
Current lower Souhegan Instream Flow Conditions Microsoft Excel Symbol

Reference Information



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NH Department of Environmental Services | 29 Hazen Drive | PO Box 95 | Concord, NH 03302-0095
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