Grave Creek is a fourth order tributary to the Tobacco River, with a watershed area of approximately 55 square miles, and the only Montana bull trout spawning tributary to Lake Koocanusa. Grave Creek also provides water for westslope cutthroat trout habitat, agriculture and other riparian dependent resources. Timber harvest and road construction in the headwaters and agriculture, grazing, riparian vegetation losses, channel manipulation, and residential and industrial encroachment in lower reaches have impacted the lower three miles of Grave Creek by reducing stream stability, the quality and quantity of available fish habitat, and the composition of the riparian community. Because of these conditions, the Montana Department of Environmental Quality included Grave Creek on the 1996 and 2004 303(d) list of impaired streams.
The KRN led a collaborative effort to improve the condition of lower Grave Creek that included local landowners, state and federal agencies and private foundations to implement a phased restoration effort that reconstructed 1.55 miles of lower Grave Creek.
The Grave Creek Demonstration Project was the first phase of restoration that occurred in the fall 2001 and reconstructed about 1,000 feet of stream channel. Prior to the project, about half the length of the project consisted of a 20 feet high eroding bank that contributed substantial sediment annually to Grave Creek. This project constructed an armored bank terrace to prevent the stream from accessing the toe of the eroding slope, and installed revegetation treatments to provide long-term stability. Throughout the remainder of the project area, additional bank stabilizing and revegetation treatments were installed to center the stream flow, increase fisheries pool habitat and complexity, and stabilize stream banks.
Restoration efforts on lower Grave Creek continued in the fall of 2002 where the previous project ended. This phase of the project restored an additional 4,300 feet of stream channel by installing 41 stream restoration structures that increased channel diversity and reduced stream gradient by increasing stream length. The restoration resulted in reduced of stream width and width to depth ratio and increased stream depth. Project cooperators later revisited this site in 2008 to restore riparian vegetation.
The third and final phase of restoration on lower Grave Creek was completed in 2004 with the reconstruction of over 3,050 feet of stream channel, which resulted in an overall increase in stream length by about 10 percent. The project installed 26 stream restoration structures that provided bank stabilization, gradient control and increased pool habitat.
The 2001 project also accommodated an existing water right within the project area by installing a headgate at the point of diversion and a vertical panel fish screen to eliminate juvenile fish entrainment in the irrigation ditch. The original fish screen was damaged in 2014 and replaced with an upgraded horizontal panel fish screen in 2018.
Irrigation fish screen damaged by windfall New and improved fish screen 2018
The KRN investigated the effectiveness of the restoration efforts and concluded substantial improvements in fine sediment, aquatic habitat, and bank stability had been achieved. This report can be accessed here. Montana Fish, Wildlife and Parks monitors fish density within this section of Grave Creek and concluded that bull trout density significantly increased after the restoration work.
Juvenile bull trout increased after project Pool habitat post restoration Woody debris post restoration Post restoration