Low-cost, natural treatments bring steady recovery to a degraded trout stream

摘要

Severe streambank erosion, a deeply incised channel, and lack of riparian vegetation were all obvious problems for this reach of Tom Miner Creek in southwestern Montana. Trout Headwaters Inc., of Livingston, Mont, was contacted by a private landowner with concerns about the effects high erosion rates were having on the property's trout fishery. The reach was so severely incised (deeply lowered below its natural floodplain) that the stream could no longer access its floodplain, and the incised condition increased the rate of erosion, adding an undesirable amount of silt to the stream. As the owner suspected, silt deposits had severely degraded vital trout spawning habitat, decreased aquatic insect habitat and led to an overall reduction in the productivity of the system. The bare banks left any newly established vegetation vulnerable to the power of spring floods. This left the stream corridor completely devoid of woody vegetation; a crucial component for erosion control, shade, instream fish habitat, nesting cover, forage and overall high biodiversity. After careful assessment and hydraulic analysis, low-cost, simple to install biostabilization techniques were recommended to combat the erosion problem and also accommodate the property owner's desired budget. This natural restoration treatment uses young, native willows, harvested on site, and bundled together to form fascines. The dormant fascines were anchored into the toe of eroding banks to slow the erosive effects of the water. To reduce costs even further, and to learn these simple technique, ranch management and staff participated in the installation. Anchoring fascines into place allowed the willows to sprout and grow, establishing riparian vegetation, restoring the floodplain and decreasing bank erosion. THI designed a monitoring program for the project area, and in just a few years, with no other treatment, the creek now has a healthy and functioning floodplain. The use of fascines decreased bank failure, decreased fine sediment load, decreased bank erosion, increased riparian and aquatic habitat and increased overall species diversity. This project demonstrates the use of low-cost and low-impact alternatives for bank stabilization and stream enhancement. This method is easily implemented and easily replicated. It is a low-maintenance alternative requiring little to no follow up. Biostabilization approaches are environmentally sustainable, more cost-effective and have a higher aesthetic value than the use of hard armoring techniques such as concrete, rock or other foreign material.