Latah Soil and Water Conservation District

Channel Realignment - Corral Creek

Channel Realignment - Corral Creek

Location: Racetrack reach of Corral Creek, a tributary of the Potlatch River in Latah County, Idaho (Northern Rockies Ecosystem)
Description: This section of stream channel was straightened and widened in the early 1900s to accomodate construction of a horse racing track. The higher velocity of flow in the straightened channel causes bank and bed erosion, adding sediment and degrading downstream water quality. Because of the deeper, straighter channel, and because of the construction of a berm for the race track, the connection with the adjacent floodplain is lost and the water exits the system too quickly. Diverting the flow back into the shallower, more sinuous historic channel will slow the flow through the meadow, increase hydration of the meadow, increase frequency of flood events, create more pool habitat for juvenile steelhead, and improve wetland habitat. Following instream construction, scheduled for 2013, bare areas will be stabilized through combinations of seeding and mulching, planting, and use of sedge mats. Livestock will be excluded from the restoration area for several years to allow the establishment of native vegetation. Plant survival will be checked after 1, 3, and 5 years. Ground water and surface water elevations will also be monitored.
Status: Active

Location: Vassar Meadows/Camp 10 reaches of Corral Creek, a tributary of the Potlatch River in Latah County, Idaho (Northern Rockies Ecosystem). Ground is owned by the USDA Forest Service; the Forest Service requested our assistance on this project.
Description: Below Vassar Meadows, a logging camp (Camp 10) was constructed on a meadow, and flow of the creek through the meadow may have been deliberately diverted into the borrow ditches to dry out the meadow. The higher velocity of flow in the straightened channel caused bank and bed erosion, adding sediment and degrading downstream water quality. Because of the deeper, straighter channel, the connection with the adjacent floodplain was impaired and the water exited the system too quickly. In 2012 we will begin topographic surveys of the meadows and stream channel in order to begin development of alternative designs. We will also begin hydrologic and geomorphologic analyses and start the permitting and consultation process. Possible treatments for one part of the degraded reach may include installation of plugs for diversion and creation of wetland cells, similar to the Tee/Colby Meadows reach described above. Photopoints will be established to document the existing conditions, future construction, and revegetation trends. Groundwater and surface water elevation monitoring was established in 2011 to collect baseline data, and will continue through construction and following construction.
Status: Active

Location: Tee/Colby Meadows reaches of Corral Creek, a tributary of the Potlatch River in Latah County, Idaho (Northern Rockies Ecosystem)
Description: During logging operations in the early 1900s, temporary rail lines called shay lines were constructed throughout the meadows of the Potlatch River watershed. Using the shay lines, crews moved cut logs from the woods down to the meadows and on to the main rail yards and rail lines, and eventually to the mills. Due to the construction and continued existence of these berms, criss-crossing the meadows and the historic channel, the flow of the East Fork of Corral Creek diverted from its channel into the borrow ditches. This inadvertent straightening of the stream channel degraded water quality and eliminated steelhead rearing habitat. The higher velocity of flow in the straightened channel caused bank and bed erosion, adding sediment and degrading downstream water quality. Because of the deeper, straighter channel, the connection with the adjacent floodplain was impaired and the water quickly exited the system. In 2009 we began construction of a series of channel or "ditch" plugs to create diversions and wetland cells. By diverting the flow back into the shallower, more sinuous historic channel, the flow of the East Fork of Corral Creek has been slowed, hydration of the meadow and frequency of flood events has increased in the meadow system, and habitat for juvenile steelhead has increased. Wetland habitat has also improved by converting portions of the degraded channel into a series of wetland cells, which further detain water in the meadow system and increase recharge. Following construction, ditch plugs and other bare areas were seeded with a mix of native grasses and forbs and planted with native grasses, forbs, sedges, rushes, bulrushes, and woody species. Seeded areas were stabilized with mulch and/or erosion control material. Sedge mats were also used to stabilize bare areas. In order to further improve the meadow hydrology, a new upland road was constructed so that the road through the meadow could be abandoned. Livestock exclusion fencing was installed in 2010 to protect the majority of the historic East Fork of Corral Creek and the newly created wetland area. To further draw the cattle out of the meadow, the landowner selectively logged some of the adjacent timber ground to open the canopy and improve forage in the uplands. Three ponds were constructed in the uplands in 2011 to provide water and further draw the cattle to the uplands. Planting has continued to revegetate construction areas, restore wetlands, and stabilize cutbanks. Photopoints are being used to document changes in vegetation. Groundwater and surface water elevations are also being monitored.
Status: Active

Location: Avulsion/Round Meadow reaches of Corral Creek, a tributary of the Potlatch River in Latah County, Idaho (Northern Rockies Ecosystem)
Description: Between 2005 and 2008, Corral Creek (Avulsion reach) experienced erosion events that allowed the flow to be diverted from the narrow, sinuous, well-vegetated historic channel to an old road bed associated with early 20th century logging. In Round Meadow, upstream of the Avulsion location, the flow had already been captured in borrow ditches associated with the temporary rail lines known as shay lines which were used to transport logs. The straight, wide ditch sections resulted in higher flow velocities, causing ongoing bank and bed erosion, adding sediment and degrading downstream water quality, and allowing the flow to exit the system more rapidly than historic conditions permitted. In 2008 we began construction of channel plugs to divert the flow back into the shallower, more sinuous historic channel to slow the flow through the meadow, increase hydration of the meadow, decrease erosion, create more pool habitat for juvenile steelhead, and improve wetland habitat. In order to reduce erosion pressure on the main diversion channel plug, we diverted flow of a minor tributary northward by cutting in a new channel. Following the instream construction the site was seeded with a mix of native grasses and forbs and planted with native grasses, forbs, sedges, rushes, bulrushes, and woody species. Seeded areas were stabilized with mulch and/or erosion control material. Sedge mats were also used to stabilize bare areas. Livestock fencing installed in 2009 excludes cattle from the restoration area to allow establishment of the native vegetation and recovery of the meadow vegetation. Photopoints will document changes in vegetation.
Status: Active

Summaries prepared by Trish Heekin, Resource Conservation Planner, Latah Soil and Water Conservation District, 2012

Latah Soil and Water Conservation District
Gritman Medical Park (Federal Building)
220 East 5th Street, Suite 208
Moscow, Idaho 83843
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