ERO prepared the Compensatory Mitigation Plan (CMP) and Ecological Function Approach (EFA) for the Chatfield Reservoir Storage Reallocation Project. The project reallocates 20,600 acre-feet of Chatfield’s flood control storage to multi-purpose water supply storage. This additional storage space is used by municipal and agricultural water providers to help meet the diverse needs of Colorado. ERO coordinated with numerous stakeholders, including the project participants, the U.S. Army Corps of Engineers (Corps), Colorado Parks and Wildlife, Denver Audubon, the U.S. Fish and Wildlife Service, and Denver area municipalities to develop a CMP and EFA that effectively addressed impacts on natural resources associated with the project and incorporated adaptive management. Among the natural resources of concern were the endangered Preble’s meadow jumping mouse, migratory birds, and wetlands. ERO provided independent technical review services during project implementation, which included developing habitat design criteria; review of impacts, mitigation area baseline, and mitigation credits; development of a GIS database of mitigation sites; assessing off-site mitigation areas; providing training for regulatory personnel on the EFA; preparation of a revised biological assessment; development of an adaptive tree management plan; performing raptor and migratory bird surveys; and conducting ongoing groundwater monitoring. ERO has been conducting annual monitoring for 283 acres of on-site mitigation that has been completed, as well as monitoring an additional 223 acres of restored temporarily disturbed areas associated with the project and 495 acres of the additional water storage area (fluctuation zone), and leading implementation of adaptive management actions for these areas as needed. The project requires close coordination with the Chatfield Reallocation Mitigation Company, multiple design engineering firms including Muller Engineering, multiple contractors including Western States Reclamation, and representatives from numerous federal, state, and local agencies.
ERO was also responsible for ensuring Section 106 compliance for the project. Task activities included completing a regulatory compliance plan, coordinating with the Corps and the U.S. Forest Service (USFS), completing a cultural resource assessment, evaluative testing, geomorphology assessment and exploratory testing, developing a Memorandum of Agreement to resolve adverse effects, Level II treatment, geotechnical activity monitoring, and developing a construction contractor training module. Ongoing tasks include implementing avoidance measures, historic property construction monitoring, and serving as the on-call discovery contractor. ERO successfully achieved Section 106 compliance from both the Corps and the USFS within an accelerated timeframe to accommodate the construction schedule.
