2010-11-22_REVISION - M2009023 (6)

Home Browse Search

Final Mitigation Plan for Long Hollow Reservoir La Plata River Mitigation Site (Permit No. 200375243) including with the operational guidelines" developed by the NRC and contained in Appendix B of RGL 02-02. A semi-quantitative functional assessment for the impacted resources in the Project was described in detail in the Revised Mitigation Plan. The characteristics of the wetlands, perennial and ephemeral channels, and proposed mitigation sites are based on numerous field observations. The created wetlands are scored higher in the functional assessment for wildlife habitat since they will have more native trees and shrubs, are located next to a relatively large pond (open water), and immediately adjacent to a relatively large and intact riparian zone for the La Plata River. They were also scored slightly higher for recreation since they will be a relatively large complex with the pond. The wetlands were not scored higher for flood flow attenuation, sediment retention, or water quality improvement even though they will be located in shallow depressions with increased flood storage capacity. This is because it is not certain how much and often the created wetlands will receive flood flow or stormwater runoff. However, the setting of the wetlands in depressions will tend to increase their capacity for these functions compared to the impacted wetlands. Based on the functional assessment, the total Functional Capacity (FC) of the impacted wetlands and channel from the Project is 3.5. The total FC of the proposed La Plata River mitigation is 5.6. This indicates that there will be a significant increase in wetland and aquatic functions if the mitigation for the proposed impacts is successful. The relatively large projected increase also suggests that there will be a net gain in functions even if slightly different assumptions are used in the analysis. The La Plata River mitigation site is scheduled for construction in fall or winter 2010 to mitigate for the direct impacts to wetlands and waters of the U.S. that will occur as a result of fill from construction of the dam, which will occur first (June 2011) and from the eventual footprint of the full pool (2013). There will be no temporal loss of wetlands with this Project schedule. 2.6 Mitigation Work Plan As shown in Figure 3, establishment of 3.75 acres of wetlands will occur on the east side of an existing gravel pit pond by excavating below the water table, then placing topsoil that is stockpiled on the site (see Figure 2) to near the elevation of the water table. All excavated August 2010 Bikis Water Consultants, LLC Page 7