Why/How Habitat Projects Are Undertaken by MN TU
Degraded in-stream and riparian habitat of coldwater streams, rivers and lakes is a conservation issue of statewide importance that requires habitat restoration and enhancement efforts. Trout Unlimited members and chapters have been undertaking habitat restoration and enhancement projects in Minnesota for several decades. The specific fish habitat enhancement methods used on each stream or lake vary depending upon the distinct natural resource characteristics of each watershed and ecological region, the limiting factors identified for each stream or lake, and the variations in the type and magnitude of poor land uses practices within each watershed. Minnesota Trout Unlimited tailors each project accordingly, using the best available science, in close consultation with resource professionals within the Minnesota Department of Natural Resources (“MNDNR”). Our local chapter members share their first-hand knowledge of the watersheds and the myriad lessons they have learned from over 30 years of planning, funding, and completing fish habitat restoration and enhancement projects in Minnesota.
Purposes: Each project is designed and completed using techniques selected to accomplish one or more of the following purposes: (a) reduce stream bank erosion and associated sedimentation downstream, (b) reconnect streams to their flood plains to reduce negative impacts from severe flooding, (c) increase natural reproduction of trout and other aquatic organisms, (d) maintain or increase adult trout abundance, (e) increase habitat and biodiversity for both invertebrates and other non-game species, (f) be long lasting with minimal maintenance required, and (g) improve angler access and participation.
Habitat enhancement methods used may include one or more of the following techniques: (1) sloping back stream banks to both remove accumulated sediments eroded from uplands areas and better reconnect the stream to its floodplain, (2) removing undesirable woody vegetation (invasive box elder, buckthorn, etc.) from riparian corridors to enable removal of accumulated sediments, reduce competition with desirable plant and grass species, and allow beneficial energy inputs (sunlight) to reach the streams, (3) stabilizing stream banks using vegetation and/or rock, (4) selectively installing overhead and other in-stream cover for trout, (5) installing soil erosion blankets (6) mulching and seeding exposed stream banks (including native prairie plant species where appropriate), (7) improving or maintaining stream access roads and stream crossings, (8) fencing grassy riparian corridors to prevent damage from over grazing, and (9) in Northern forested watersheds with little cold groundwater, planting desirable trees in riparian areas (especially former beaver meadows infested with invasive reed canary grass) to provide shade for the stream channel and help cool the water.
Agricultural area example: Many streams in the agricultural areas of southern and central Minnesota have been negatively impacted by many decades of poor land management practices. How and why the various habitat enhancement actions are typically taken here is best illustrated by the following example:
Erosion has led to wider, shallower and warmer streams, as well as excessive streamside sediments which regularly erode, covering food production and trout reproduction areas. In many cases shallow rooted invasive trees have taken over the riparian corridors, out competing native vegetation which better secures soils, and reducing energy inputs to the stream ecosystem. To remedy this, a typical enhancement project will involve several steps. First, invasive trees are removed from the riparian zone and steep, eroding banks are graded by machinery to remove excess sediments deposited here from upland areas. Importantly, this reconnects the stream to its flood plain. Since many of these agricultural watersheds still experience periodic severe flooding, select portions of the stream banks are then reinforced with indigenous rock from local quarries. In lower gradient watersheds, or watersheds where flows are more stable, little or no rock is used. After enhancement work is completed the streams flow faster and become deeper, keeping them cooler and providing natural overhead cover through depth and the scouring of sediments deposited by decades of erosion.
Second, overhead cover habitat is created. Bank degradation and the removal of native prairie have dramatically decreased protective overhead cover in the riparian zone. Two methods are used to remedy this situation: increasing the stream’s depth, which alone provides natural cover to trout, and installing overhead cover structures in select stream banks. Wooden structures are often installed into banks in hydraulically suitable locations and reinforced with rock as a way to restore or recreate the undercut banks which had existed before settlement and agricultural land use altered the more stable flows which had gradually created and maintained them.
Finally, vegetation is reestablished in the re-graded riparian corridor to further stabilize banks and act as buffer strips to improve water quality. Depending upon the specific site conditions, landowner cooperation, and agricultural use, native prairie grasses are planted along the stream corridors, although often mixed with fast sprouting annual grains to anchor soils the first year.
Taken together, these actions directly enhance or restore physical habitat, and typically increase overall trout abundance, population structure, the number of larger trout, and levels of successful natural reproduction. In addition to the benefits to anglers of increased trout habitat and trout abundance, project benefits extending well downstream include reduced erosion and sedimentation, improved water quality and numerous wildlife benefits.
On Outdoor Heritage Fund Projects: All of the Minnesota TU projects on which money from the Outdoor Heritage Fund is used are located on existing public property or on land permanently protected by a conservation and management easement under the aquatic management area system.
Minnesota TU Projects