Topock Marsh is a large wetland adjacent to the Colorado River and main feature of Havasu National Wildlife Refuge (Havasu NWR) in southern Arizona. In 2010, U.S. Fish and Wildlife Service (FWS) and Bureau of Reclamation began a project to improve water management capabilities at Topock Marsh and protect habitats and species. Initial construction required a drawdown, which caused below-average inflows and water depths in 2010-2011. Co-applicants Daniels and Haegele of FORT monitored Topock Marsh during the drawdown and immediately after, thus obtained information on immediate effects. However, stress from the drawdown may have a delayed effect on aquatic resources; additionally, significant changes to the infrastructure and water operations have since occurred. We propose to build upon FORT’s previous work by providing an assemblage of biotic, abiotic, and hydrologic data needed by FWS to better understand the health and function of Topock Marsh under various hydrologic conditions. FORT will develop a Decision Support System (DSS) utilizing a spatially-explicit GIS package of historical data, habitat indices, and analytical tools to synthesize outputs for hydrologic time periods. This approach will help FWS use the best available science to determine more effective water management strategies. Technologies used in this study could also be applied elsewhere within the region. Deliverables will include: high-resolution ortho-rectified imagery of Topock Marsh; a DSS tool that can be used by Havasu NWR to compare habitat availability associated with 3 hydrologic scenarios (dry, average, wet years); and a final report detailing all results. This project addresses Priority Critical Manage-ment Questions 1 and 2, through the integration of ecological and hydrologic information into a GIS-based decision framework to assist refuge management make better informed decisions about refuge operations and better understand results of those decisions ecologically by providing decision support tools to identify sensitive species and processes.
