What is a “Watershed”?
Virtually any place that sheds water! The Chocorua Lake watershed includes the area surrounding the lake where water moves over and through the landscape and into the lake. The Chocorua Lake basin comprises more than 13 square miles of uplands where rain and snowmelt filters through the soils and accumulates in various rivers and streams, both perennial and intermittent, that find their way to the lake.
Streams flowing into the lake provide connectivity between the upland forests and lake, carrying nutrients, providing habitats for plants and animals, and acting as corridors for the movement of wildlife. We often think of nutrients carried downstream by the flow of water, but they move upstream as well. Fish, birds, mammals, amphibians and reptiles, and insects crossing into and out of streams and into the uplands in their yearly movements are part of the nutrient cycles in a watershed. The larger lake, its tributaries, and all of the little wetlands associated are connected to each other by the water cycle as well as the animals that move over and through the landscape.
Brook Trout Habitat Project
In 2018 the CLC began a project with funding from the Natural Resources Conservation Service (NCRS) to improve stream habitat for native brook trout on Allen Brook, which flows through the Scott Reserve. The brook is north of the lake and flows into the Chocorua River below the old mill on Scott Road. The addition of “woody materials” involves dropping tree lengths into the stream at measured distances to slow the water, creating pools and runs (stretches of smooth water where sand and gravel can settle). The idea is to supplement the natural supplies of materials in the water, enhancing what is there and creating a diverse structure to the stream. Past timber harvest techniques removed mature trees near stream banks and restricted slash left in the water, thereby reducing the supply of stream slowing forest materials.
This trout habitat project, with the help of Dick Fortin and Tin Mountain Conservation Center, seeks to restore the diversity of structure and composition in the streams that is so important to trout and their food sources. Brook trout are a cold-water species: cold clear waters rich in oxygen, an ample invertebrate food supply, and gravel spawning beds lead to healthy brook trout populations. Deep pools where they can “hide” during warm spells, gravelly bottomed stretches for laying eggs, and well-vegetated banks providing cooling shade and cover, are all important habitat components. The adding of woody materials helps to create these important characteristics by slowing water and trapping leafy materials as they wash into the stream.
And, because of watershed—remember that word from above!—adding woody materials helps maintain water quality not only in the stream, but in lakes and ponds below! The woody materials slow water velocity during spring run-off and high water events, and act as filters to reduce the amount of sediments and organic materials accumulating downstream. High water velocities can impact streams by carving the banks and causing increased erosion, further adding to sedimentation in lakes and ponds. Without the slowing of water, the stream can bypass the normal floodplains that are so important to water quality and the plants and animals that depend on them.
What’s Next and What you can do
During the summer of 2019 the CLC is working with the Nature Conservancy and another private landowner to add to the 1000 feet of stream that was improved in 2018. With funding from the Carroll County Conservation District, another 3000 feet of Allen Brook, a tributary of the Chocorua River, will be improved. In addition to the work of establishing woody materials in the brook, a full habitat survey will be done prior to the work. Trout surveys will take place pre- and post efforts to measure the impacts of the additions to longer-term success.
The NRCS works with landowners on trout enhancement projects and may provide cost-share funding, so if you have a stream going through your land, it is worth exploring what grants may be available to you. The future of our wild brook trout populations may depend on projects like these to help them adjust to a changing climate. For more information contact your local NRCS office.
Banner: Pitcher plants. Photo: Greg Shute