When it comes to managing rivers for water quantity, the key question is, “How much is too little?” This is a particularly vexing issue given the dynamic nature of both stream flows and the demands on those flows. By focusing on a river’s flow pattern and applying management to maintain that pattern, the New Hampshire Instream Flow Program has developed the tools needed to provide sustainable water resource protections for people and the ecosystem.
Many attempts have been made around the world to define effective stream flow protection. Management to maintain these protections must be integrated into an existing framework of water supply infrastructure and societal expectations for water availability. Finding acceptable and effective protection criteria and then equally acceptable and effective management actions has stymied many instream programs.
The New Hampshire program recognizes that river flows vary greatly through the seasons, and native plants and animals have adapted to low summer flows, as well as to the typical spring floods. Therefore, the Instream Flow Program determines the natural patterns of flows specifically for each river, and then works with local water users and dam owners to ensure that these patterns are maintained while water users’ needs are met. Management includes reductions in loss and waste, event-specific changes in water use, development of alternate water supplies to cope with low flow conditions, and releases from impoundments to reset the natural stream flow pattern.
Results to Date:
Last spring, after nearly 15 years of work on two rivers in the pilot phase of the program, the New Hampshire Legislature and Governor enacted a bill to expand the Instream Flow Program to cover 16 additional rivers in the state.
Fully implemented, the program will result in rivers that have healthy, balanced ecosystems and robust water supplies for drinking water, business, and other off-stream uses, and which are capable of fully providing for water needs during low-flow conditions. The program brings more water users into the state’s water conservation program, resulting in less water being lost or wasted. The program supports water users in developing water sources that are drought-resistant.
Management actions during the first two years of the program’s implementation on two pilot rivers have been successful in restoring the stream flow pattern following excessive period of low flows. Water users on those rivers have developed alternate water supplies that meet their needs and reduce stresses on their rivers. The small impacts of the occasional use of releases from the upstream impoundments have been accepted by lake front property owners, and they have recognized the importance of harmonizing their use of the “lake” with the needs of the rivers.
To the Department of Environmental Services’ knowledge, no other state has approached the protection of instream flows in this manner, but the New Hampshire approach should be readily transferable to other states. More information can be found at: www.des.nh.gov/organization/divisions/water/wmb/rivers/instream.