Posted on December 18, 2024
IDAHO – Silver Creek in Blaine County, Idaho is a fisherman’s paradise and famed trout fishery with stunning clear water. But since the USGS began recording flow data in 1974, there has been a significant decline in the flow rates in Silver Creek. Over the past few decades, the fish habitat has been adversely affected and diminished. In 2010 The Nature Conservancy began developing a restoration and enhancement plan for the Silver Creek watershed. This plan included collecting data from the tributaries to Silver Creek by regularly measuring stream flow rates, water temperature, dissolved oxygen and sediment conditions. The data was needed to better understand the creeks and to be able to implement an effective management and restoration plan.
In partnership with the Silver Creek Alliance and Idaho Fish and Game, private landowners and The Nature Conservancy have restored several miles of stream channels, rehabilitated side channels, enhanced and constructed wetlands, removed sediment build up at targeted sites, and improved acres of wildlife habitat. “These outcomes will benefit the entire watershed with better streamflow and habitat conditions for fish, waterfowl and other wildlife, as well as improve the overall resiliency of the Preserve in the face of climate change. The goals of this project were to prepare the Silver Creek system to better withstand fluctuating conditions caused by climate change, such as reduced water supply and higher temperatures, as well as remove sediment buildup in the creek. To achieve this, the project returned the creek to a natural meandering path that is nearly half a mile longer than pre-restoration, supports better flows and avoids sediment deposits.” (https://www.nature.org/en-us/newsroom/idaho-stalker-creek-restoration/)
Because the adjacent landowners appreciate the importance of preserving the stream conditions, some parts of the restoration projects in the Silver Creek watershed have been with the landowners’ own funding. Landowners adjacent to the Silver Creek Preserve are part of a conservation effort that protects an additional 12,000 acres through conservation easements.
One such privately funded project was on lower Chaney Creek. Chaney Creek is a near-three mile-long creek located in Blaine County, Idaho that lies a little over 100 miles east of Boise. Surrounded by acres of farmland, natural woodlands and sagebrush prairie, the creek is a major tributary in the Silver Creek watershed.
When the ENVIROdredge team started work on Chaney Creek, there was a severe lack of water depth and an excess of plants and sediment restricting water flow. The landowner also requested that the team make the creek more accessible and visually pleasing.
Knowing this, the team aimed to clear the creek of any sediment that had collected from upstream, while simultaneously clearing aquatic plants and brush. In doing so, the creek’s natural depth and bank were restored.
The results were easy to see, with the water once again crystal clear and with a visibility of around six to seven feet. The removal of the sediment and plants was apparent, and the aesthetic of the creek was once again pristine.
ENVIROdredge’s traditional dredging process is unique for two reasons, both of which are beneficial towards this project in Chaney Creek. The first is that the process utilizes a floating barge on the water that consists of a hydraulic-powered suction pump – which basically works as a large, water-powered vacuum. By working from the water, the riparian area and shoreline are left undisturbed and in their natural state.
When using a hydraulic pump, the material sucked out of the creek must have a place to go. ENVIROdredge, in conjunction with Rivhab, PLLC, a river and wetland engineering firm based in Eagle, Idaho, worked to develop a plan for the dewatering of the sediment. The material removed from the creek was pumped through a temporary pipeline and deposited into a dewatering basin that was excavated onsite. As the material settled, the nutrient-rich water was dispersed into a nearby field, making the soil more viable for farming. After the basin is dry and leveled, the material can be covered with crops or native grasses.
ABOVE: Showing sediment accumulation from upstream and the restored water depth where the dredge has previously worked.
The second benefit is not only the beneficial re-use of the material, but the monitoring of downstream turbidity that could cause stress to the fish population. The state of Idaho has a Total Suspended Solids requirement of a “less than fifty parts per million” when dredging a natural body of water. This requirement means that there must be particular care in monitoring any discharge waters that return to the watershed. ENVIROdredge’s hydraulic suction dredging using the patented self-propelled IMS Model 5012 HP Versi-Dredge® is an environmentally responsible method of sediment removal that allows the turbidity to be monitored and controlled.
As soon as the work was completed on lower Chaney Creek, the Versi-Dredge was moved to Loving Creek, another major tributary to Silver Creek. At Loving Creek the nutrient-rich sediment was discharged directly into farm fields to later be tilled into the soil.
ABOVE: Sediment repurposed in farm fields.
ABOVE: A closer view of the sediment spread over adjacent farmland adding nutrient rich soil for increasing crop yields.
Stream restoration is an integral part of the overall management plan for Idaho’s creeks, which are necessary for the local economy in farming, fishing, and wildlife. ENVIROdredge is proud to work with Rivhab Engineering and the conservation groups that aim to protect some of Idaho’s greatest resources.
By: Tammy Perry
