Alamosa River Restoration Project

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' and are being addressed partially through the Superfund process being conducted at Summitville. Sections of the river are classified for agriculture, recreation (Class 2) and are use protected. Other sections are classified as Aquatic life Cold 1 and Aquatic Life Cold 2. TMDL's have not been established for the sections of the Alamosa River that are part of the project area. In the early 1990's, a Heap Leach gold mining operation at Summitville discharged toxic chemicals and metals into the river, killing all aquatic life for approximately 20 miles downstream to Terrace Reservoir. The remainder of the river, from Terrace Reservoir and east to US Hwy 285 (another 24 miles) was also severely damaged. Fish and other biological life were destroyed in holding ponds, farm reservoirs (many stocked for recreation) and irrigation ditches. Ditches that take water from the Alamosa River and use the La Jara Creek to transport ' water to farms south and east of the La Jara Creek resulted in the killing of aquatic life in the La Jara Creek, as well. Heavy metals and acid mine drainage have damaged irrigation equipment, such as sprinklers, head gates and culverts. The soil chemistry on some irrigated lands has been altered. Summitville is now a superfund site and clean up at the site is ongoing. Fortunately, residents downstream have seen a huge improvement in water quality. Discharges from the mine's heap leach pad, mine wastes and tailings, and various underground sources and adits are now controlled and treated before discharge to the river. There is still considerable contamination in the river bed sediments between Summitville and Terrace ' Reservoir. These water quality problems due to bedload are not being monitored, but are addressed in the Alamosa River Watershed Restoration Master Plan. These upstream sediment issues are not part of the scope for this 319 project. The Alamosa River below Terrace reservoir received a large discharge of sediment in 2003. Repair work on the primary outlet gates of Terrace Reservoir led to an unplanned discharge of thousands of tons of metal rich sediment from the reservoir pool as the Alamosa River channeled it's way through the sediments at the bottom of the reservoir once the reservoir was drained. These sediments filled the actual river channel with up to 2 to 3 feet of muck (See Figure 3). This discharge was not part of the impacts intended to be addressed with this 319 project, nor was the discharge properly permitted with the US Army Corps or State 401 program. It did, however, forestall the restoration program for an entire year. The consecutive runoff season washed most of the muck from the stream bed and carried it downstream. This 319 project focuses on the reduction of stream bank erosion and subsequent streambed deposits, as identified in the 303D listing. The reduction in streambed deposits is accomplished by restoring a geomorphically stable river, where there is no long term aggradation or degradation. In nature's model, this geomorphically stable form of the river is usually accompanied by a mature component of woody riparian vegetation along the river's banks. While this restoration effort includes some re-vegetation efforts, transplants are not often large enough or widespread enough to control the shear stress of the river immediately after construction activities. This basic timing problem has resulted in the development of various techniques using large rocks to prevent streambank erosion. The simplest form of rock use for erosion protection is riprap: a layer of rock placed continuously on the surface of the stream bank, whose size and thickness resists movement by the river. Amore sophisticated use of large rock comes in the form of "vane" type structures. These structures use rocks fit together to form 7