Final Report Upper Truckee River Reclamation Project
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Final Report Upper Truckee River Reclamation Project January 31, 2003 Page III-41 grade control and accommodate over bank flows, therefore, hydrologic function of any wetlands/waters of the U.S. should be improved by these measures and the impacts would not be considered significant. Placement of boulders and logs in the stream channel in Reaches 2, 3, 4, 5, and 6 can be considered fill in waters of the U.S., however the purpose of installing these measures is to improve bank stability and aquatic habitat. Re-vegetation of the in-channel enhancements will further improve these wetland functional values. No significant adverse impact to wetlands will result from these measures. Local drainage patterns will be altered by implementation of Alternative 3. Improvement of hydrologic functions is expected to retain water in project site wetlands longer. Runoff from storm events will be temporarily stored and released downstream more slowly. Flooding hazards will be reduced outside the project area. This is considered a positive impact. Overall, the long-term impacts of Alternative 3 on wetlands in the project area would be positive. Downstream wetlands and waters of the U.S. would also benefit from reduced erosion and enhanced water quality improvement functions of the project area wetlands. III.C.4.2 Unavoidable Adverse Impacts Some short-term adverse impacts related to water quality and habitat functional values are possible during the construction phase and until vegetation is successfully established on disturbed areas. These impacts are substantially the same for both Alternatives 2 and 3. Soil will be disturbed and vegetation removed during construction, which could result in increased erosion, turbidity and sedimentation in wetlands and waters of the U.S. in the area of influence. Equipment and vehicles used during construction could accidentally introduce pollutants into wetlands and waters of the U.S. in the project area. Demolition of the existing bridge and ford crossing and construction of replacement bridges could accidentally introduce debris and pollutants into wetlands and waters of the U.S. as well. Construction activities will involve clearing existing vegetation, grading, placing fill, excavating soil, demolishing structures, and building bridges in and adjacent to flowing water and within the floodplain of the Upper Truckee River. The disturbed areas will be vulnerable to water erosion and/or entrainment of debris or contaminants in storm runoff until site clean up and re-vegetation are complete. Large runoff events that occur in the first several years after construction before vegetation is well established could also increase erosion and sedimentation in the area of influence. Accidental leaks and spills of chemicals, concrete leachate, or petroleum-based products such as hydraulic fluids, diesel fuel, and oil during construction could contaminate surface water and harm aquatic life and associated biological resources. Final Report Upper Truckee River Reclamation Project January 31, 2003 Page III-42 Accidental release of demolition debris to the Upper Truckee River may occur when existing structures are removed. Construction of the replacement bridges could also introduce contaminants into or increase turbidity in the river or adjacent wetlands. Habitat functional values will be disturbed during the construction phase. Some habitat elements, such as willows and lodge pole pines, will be removed. Replacement trees, especially pines, will take a long time to grow back. These trees may provide cover, nesting, rearing, resting, and feeding functions for birds and mammals. Some deeper depressional areas within existing wetlands in the project area could be filled in. These depressions may provide breeding, rearing, and feeding functional values for amphibians. III.C.4.3 Proposed Mitigation To address potential adverse impacts to the water quality functional values of wetlands in the area of influence the following mitigation measures are recommended: 1. Construction activities should be avoided during the wet season (approximately October – May) to the extent possible. If construction must take place during this time, upstream flows should be continuously monitored in real-time to assure that equipment, vehicles, supplies, and personnel are not caught in the floodplain during over bank flow events. 2. Storage of equipment, vehicles, and construction materials, including soil fill material in the project area should only take place during the dry season (May – October). 3. Erosion control measures such as small catch basins, filter fabrics, straw bale or coir log barriers that prevent soil and sediment from leaving the project site shall be installed, monitored and maintained during construction activities. 4. Vehicle and equipment washing, refueling, and maintenance activities should not occur in meadow and floodplain portions of the project area. 5. Vehicles and equipment operated within the project area should be checked and maintained daily to prevent leaks of fuels, lubricants, or other fluids into wetlands or waters of the U.S. 6. To the extent practicable, desirable vegetation removed during excavation activities should be salvaged for re-vegetation of the disturbed areas. 7. Re-vegetation of disturbed and graded areas should occur prior to the onset of the first rainy season following construction. Temporary erosion protection, such as the use of erosion control blankets, shall be used on any areas that cannot be re- vegetated prior to the onset of the rainy season. Final Report Upper Truckee River Reclamation Project January 31, 2003 Page III-43 8. Re-vegetation of bank and overflow areas shall incorporate additional erosion protection measures, such as erosion control fabric, into the design. This will provide additional protection from erosion during the vegetation establishment period. These areas shall be monitored at least annually and after major runoff events. Repairs shall be made as necessary until the vegetation is well established. 9. Quality of water leaving the project area shall be monitored before, during, and after construction of the project to determine significant impacts. 10. Any de-watering or drilling fluids created during construction shall be directed to a sedimentation tank/holding facility that allows only clean water to return to the Upper Truckee River. Disposal of settled solids shall occur at an appropriate offsite location. 11. A plan shall be prepared and implemented to prevent demolition and bridge construction debris from entering the Upper Truckee River. Debris includes raw cement, concrete, metal, asphalt, paint or other coating material, oil or other petroleum products, or any other substance that could be harmful to aquatic life. The plan should include steps to be taken in the event of an accidental release of debris, including clean-up measures to protect water quality and aquatic habitat. To address potential adverse impacts to the habitat functional values of wetlands in the area of influence the following mitigation measures are recommended: 1. Construction activities should occur outside the primary breeding period (May 15 -August 15) to the extent possible. 2. Removal of snags and downed logs should be avoided where possible. Where they cannot be avoided they should be relocated within the project area. 3. Retain some existing trees and shrubs in small clumps during fill removal and other excavation activities to provide interim habitat functions and seed sources for re-vegetation. 4. Depressional areas that provide amphibian habitat should be avoided where possible. Any that must be filled shall have replacement depressions created within the meadow/floodplain area. Implementation of these mitigation measures should reduce short-term adverse impacts on wetland functional values to a level of insignificance. Final Report Upper Truckee River Reclamation Project January 31, 2003 Page III-44 III.C.5 References Bailey, Robert G. 1974. Land Capability Classification of the Lake Tahoe Basin, California-Nevada. USDA-Forest Service, South Lake Tahoe, CA. Carter, Shelly. 2002. US Army Corp of Engineers, Sacramento District. Regulatory Specialist for the Tahoe Basin. Personal communication. Carter, Virginia. 1997. “Wetland Hydrology, Water Quality, and Associated Functions” in National Water Summary on Wetland Resources. US Geological Survey Water Supply Paper 2425. http://water.usgs.gov/nwsum/WSP2425/functions.html Accessed July 18, 2002. Cowardin, L.M., V. Carter, F.C. Golet, and E.T. LaRoe. 1979. Classification of Wetlands and Deepwater Habitats of the United States. US Department of the Interior, Fish and Wildlife Service, Washington, D.C. Gibson & Skordal, Wetland Consultants. 1995. Delineation of Waters of the United States, Upper Truckee River and Wetlands Restoration Project. Global Environmental, Sacramento, CA. Environmental Laboratory. 1987. Corps of Engineers Wetlands Delineation Manual. US Army Corps of Engineers Waterways Experiment Station, Vicksburg, MS Novitski, R.P., R.D. Smith, and J.D. Fretwell. 1997. “Wetland Functions, Values, and Assessment” in National Water Summary on Wetland Resources. US Geological Survey Water Supply Paper 2425. http://water.usgs.gov/nwsum/WSP2425/functions.html Accessed July 18, 2002. Rogers, John H. 1974. Soil Survey, Tahoe Basin Area, California and Nevada. US Department of Agriculture, Soil Conservation Service and Forest Service, Washington, D.C. Sheldon, Wayne. 2002. USDA-NRCS Soil Scientist. Personal communication.