Technical Manual for Dam Owners ― Impacts of Animals on Earthen Dams (Fema 473 / September 2005)

In 1999, the Federal Emergency Management Agency (FEMA) and the Association of State Dam Safety Officials (ASDSO) jointly conducted research and a workshop to shed light on the national problem of animal intrusion damage to earthen dams and the resulting safety issues. The FEMA/ASDSO survey and workshop united dam owners, engineers, state and federal regulators, wildlife managers, foresters, and academia to form an educated and experienced front against the growing problem of earthen dam damage and failures due to animal intrusion. The infor?mation generated by roundtable discussions and survey answers indicates that while most states recognize animal intrusion as a problem, only a handful know of guidance on dams and wildlife management practices available to the dam professionals and owners. Based on input from the dam communities, FEMA/ASDSO’s mission to develop a guidance manual on the proper management of nuisance wildlife in the earthen dam environment became clear. To determine the information needs of the dam community—and therefore the most appropriate focus of this manual—FEMA/ASDSO issued a survey in 1999 and used the survey input from the 48 state dam safety officials representatives and 11 federal agencies representing the Interagency Committee on Dam Safety (ICODS). Additionally, a second survey was issued in 2003 to identify the current needs of each state, determine what nuisance wildlife and damages the states encounter, and understand which miti?gation methods are being used with success or failure. This manual provides technical guidance to dam specialists (including dam owners, operators, inspectors, state dam officials, and consulting engineers) in areas of focus identified through the two survey efforts and workshop. The purposes of this manual are to: Assist dam specialists in understanding the impacts wildlife can have on earthen dams; Provide dam specialists with basic information on habitat, range, description, and behavior of common nuisance wildlife to aid in their proper identification at the dam; Describe state-of-practice methods to prevent and mitigate adverse wildlife impacts on earthen dams. Provide state-of-practice design guidance for repair and preventive design associated with nuisance wildlife intrusion. It is envisioned that the entire dam specialist community will use this manual to augment their routine duties in earthen dam management. This manual is presented as a process toward dam inspection and management that includes wildlife damage identification and control. This manual provides technical information and guidance on: How wildlife damage adversely affects the safe operation of earthen dams; specifically, hydraulic alteration, internal and external erosion, and structural integrity losses (Chapter 2.0); Dam inspections that incorporate a biological component to sensitize dam specialists to the aspects of their dams that attract wildlife and to understand where nuisance wildlife are likely to occur on the dam (Chapter 3.0); Biological data for specific nuisance wildlife to assist the dam specialist in identifying which nuisance wildlife inhabits the dam. Biological data will also assist in controlling nuisance wildlife (e.g., listed food sources can be removed to encourage the animal to leave the area) (Chapter 4.0); Dam design specifications and methods that can be incorporated into repair of existing dams or new dam designs to prevent wildlife intrusions (Chapter 5.0); Guidelines to determine when wildlife management should occur at a dam (beyond dam repair and prevention actions) and wildlife management methods that can be implemented when control of specific nuisance wild?life populations is deemed necessary. Specific methods discussed include habitat modification, use of toxicants and fumigants, trapping, and shooting (Chapter 6.0); The fiscal issues related to appropriate and timely wildlife management at earthen dams (Chapter 7.0).