Understanding and Finding Solutions to the Problem of Sedimentation in the National Wildlife Refuge System

Abstract

The National Wildlife Refuge System (Refuge System) is a collection of public lands maintained by the U.S. Fish and Wildlife Service for migratory birds and other wildlife. Wetlands on individual National Wildlife Refuges (Refuges) may be at risk of increased sedimentation because of land use and water management practices. Increased sedimentation can reduce wetland habitat quality by altering hydrologic function, degrading water quality, and inhibiting growth of vegetation and invertebrates. On Refuges negatively affected by increased sedimentation, managers have to address complex questions about how to best remediate and mitigate the negative effects. The best way to account for these complexities is often not clear. On other Refuges, managers may not know whether sedimentation is a problem. Decision makers in the Refuge System may need to allocate resources to studying which Refuges could be at risk. Such analyses would help them understand where to direct support for managing increased sedimentation. In this paper, we summarize a case study demonstrating the use of decision-analytic tools in the development of a sedimentation management plan for Agassiz National Wildlife Refuge, Minnesota. Using what we learned from that process, we surveyed other Refuges in U.S. Fish and Wildlife Service Region 3 (an area encompassing the states of Illinois, Indiana, Iowa, Ohio, Michigan, Minnesota, Missouri, and Wisconsin) and Region 6 (an area encompassing the states of Colorado, Kansas, Montana, Nebraska, North Dakota, South Dakota, Utah, and Wyoming) about whether they experience sediment-related impacts to management. Our results show that cases of management being negatively affected by increased sedimentation are not isolated. We suggest that the Refuge System conduct a comprehensive and systematic assessment of increased sedimentation among Refuges to understand the importance of sedimentation in context with other management problems that Refuges face. The results of such an assessment could guide how the Refuge System allocates resources to studying and managing widespread stressors.

Aquatic Vegetation and Invertebrate Communities of Big Stone National Wildlife Refuge

“…Instream and off-channel reservoirs and impoundments often are characterized by reduced water and habitat quality associated with sedimentation, altered hydrology, and inputs of salts, nutrients, trace elements, and chemicals (Gleason et al 2003a(Gleason et al , 2012Juracek 2004Juracek , 2010Juracek , 2011Lee et al 2008;Graf et al 2010;Miranda and Hunt 2011;Post van der Burg et al 2014, 2017Tangen et al 2014;Rahmani et al 2018). These issues have been well-documented for systems ranging from shallow riverine impoundments to large reservoirs and managed lakes, including those located on U.S.…”