Little Devil Track River Restoration
The project will restore and protect cold-water streams for natural occurring brook trout, a sensitive, and semi-rare species, by removing an undersized culvert. The structure is a fish barrier and is creating bank erosion. The project is part of a watershed project identified in local planning efforts and through collaboration with local partners. Installing a bridge and instream geomorphology will restore fish habitat, improve stream connectivity, provide cold water refuge upstream and in tributaries, improve climate resiliency, reduce sediment loading, eliminate the current "thumb over the firehose" effect in the river, and allow for future stream habitat work.
Northeast Minnesota contains many pristine lakes and rivers which support robust populations of wild brook trout and other sensitive or semi-rare aquatic organisms. Brook trout are significant to aquatic ecosystems, recreational fishing, and an indicator of healthy watersheds. Ecological functions of streams are diminished by roads, development, and impairments that degrade the aquatic ecosystem leading to reductions in brook trout populations. Tributaries provide critical services by providing thermal refugia to brook trout populations.
Little Devil Track River (LDTR) is a tributary to Devil Track River, a tributary to Lake Superior. The in-place culvert was identified as a high priority to be replaced for fish passage, being undersized, and having structural issues. The culvert has a scour pool and a drop outlet. Cook County has determined the culvert will be replaced with a bridge to improve native brook trout habitat, build for climate resiliency with increased precipitation events, and aid in maintaining and improving water quality. Cook County and Cook County Soil and Water Conservation District (SWCD), with input from the local MN DNR Fisheries, agree an open bottom structure will be the most beneficial for the water quality and aquatic habitat. Wild Brook Trout have been identified as the primary species in the river. Secondary species in LDTR include slimy sculpin and some sensitive macro-invertebrates indicating a high-water quality biological resource such as rihithrogena, epeorus, and rychacophila.
The current culvert is impeding fish passage, pinching the river since it is not at bankfull width, and does not have natural bottom substrate to accommodate natural aquatic passage. Because it is pinching the river at this location, it is causing an increase in velocity of stream flow, like holding your thumb over a firehose. The velocity is creating shear stress on downstream banks, causing bank erosion and contributing to sediment loading in the river. The project is part of a multi-phase project to restore areas where necessary throughout the LDTR corridor and watershed for the benefit of aquatic habitat and water quality.
Cook County is working to restore the area back to a natural state, meeting the river's bankfull and flood prone width. Instream geomoprhology has been completed to ensure the new stream bottom will provide the correct roughness runs and pools for Brook Trout habitat and spawning. Cook County will provide the following habitat benefits: low flow refugia, high flow refugia, spawning habitat, searing habitat, and invertebrate habitat. To accomplish these habitat benefits, different options are being explored such as: spawning gravels, mid-channel boulder clusters to create pocket water areas, cross vanes with small plunge pools, and woody debris.
In addition to this instream work, with separate funding, Cook County SWCD will be working on stabilizing the banks downstream using natural channel design. Their project will also be a continuation of this project and instream fish habitat work along with floodplain work, riparian revegetation, reestablishment of shade trees and stream bank stabilization. This collaborative effort is planned for 2024 construction with all permitting, design, and engineering complete by December 2023.
$3,000,000 the second year is to the commissioner of natural resources for an agreement with Cook County to restore and enhance stream habitat in the Little Devil Track River.
Improved aquatic habitat indicators - The project will eliminate impediments for Brook Trout passage to 4.25-miles of upstream headwaters habitat expected to hold spawning reaches by restoring 220-feet of new channel (in place of the existing culvert). Modeling of the current culvert condition suggests the current bankfull velocities to prohibit fish passage, which would present a fish barrier. To fully restore fish passage, the project proposes to fully restore the Little Devil Track River back to its natural habitat with various features to meet aforementioned habitat: Low flow refugia, High flow refugia, Spawning habitat, Rearing habitat, and Invertebrate habitat
county levy and state and federal