The Corps is the world’s largest public engineering, design, and construction management agency, responsible for water resources infrastructure such as dams, levees, hurricane barriers, and floodgates in every state. Through its Civil Works program, the Corps plans, designs, and operates water resources infrastructure projects. The Civil Works program is organized into 3 tiers: a national headquarters in Washington, D.C.; 8 regional divisions that were established generally according to watershed boundaries; and 38 districts nationwide. In addition, the Corps maintains national and regional centers that provide technical services to Corps divisions and districts, such as support of dam safety repair projects. The Assistant Secretary of the Army for Civil Works (ASA(CW)), appointed by the President, establishes the strategic direction, develops policy, and supervises the execution of the Civil Works program. The Corps headquarters and regional division offices primarily implement policies and provide oversight to district offices. The Corps headquarters’ Dam Safety Officer (DSO), a civilian official, is responsible for all dam safety activities, including establishing policy and technical criteria for dam safety and prioritizing dam-safety-related work. The eight divisions, commanded by military officers, coordinate civil works projects in the districts within the eight respective geographic areas. The Corps districts, commanded by military officers, are responsible for planning, engineering, constructing, and managing water resources infrastructure projects in their districts as well as coordinating with the Corps’ sponsors. Most of the Corps’ dams are one of two types: earthen or concrete. According to Corps data, about 68 percent of Corps dams have earthen embankments, constructed of various types of materials such as clay, silt, sand, or gravel. Another 30 percent of Corps dams are concrete dams. Dams can have various features, such as spillway gates and conduit outlets, to control water releases, as well as auxiliary spillways to divert water flows in the event of expected maximum flood conditions. (See fig. 1.) To ensure continued safe operation, Corps dams undergo routine maintenance, such as cleaning of drains and mowing of embankments, but in some cases require major repairs, which, as defined by the Corps, are those that cost over $16 million. These repairs may be to: rehabilitate spillway gate equipment to safely pass excess water, build cutoff walls to prevent erosion to embankments or foundations fill voids in embankments or foundations with grout, build shear walls to increase dam stability, increase dam’s height to prevent overtopping, or anchor a dam to its foundation. Since 2005, the Corps has used a risk-informed approach to select dams for safety-related repairs. While integrating traditional engineering analyses and standards, the risk-informed approach aims to identify and prioritize the most critical dam safety risks rather than eliminate all potential risks. To that end, the Corps has developed the Dam Safety Action Classification (DSAC) system, based on a 5-point scale, to help guide key decisions for dam safety repairs. This risk classification system reflects the probability of a dam’s failure and resulting potential consequences due to failure. As of July 2015, the Corps has placed 309 dams (about 44 percent) in actionable categories (DSAC 1, 2, and 3) because the dams were determined to be at moderate to very high risk of failure. In particular, the Corps has classified 17 dams as DSAC 1 (very high urgency), 76 dams as DSAC 2 (high urgency), and 216 dams as DSAC 3 (moderate urgency). From fiscal year 2007 to fiscal year 2016, the Corps selected 16 of these DSAC 1 and 2 dams for repairs. According to the Corps’ Safety of Dams regulation, once a dam has been selected as needing repair according to its DSAC designation, the Corps is to take the following steps to study, design, and construct a dam safety repair project. Study: Corps district officials are to conduct a dam safety modification study to determine a long-term solution. This study is to involve risk analyses, determination of potential failure modes, evaluation of alternatives to address potential failures, and development of a recommended technical solution with its estimated cost. The study also is to identify cost share sponsors and to recommend an applicable authority for cost sharing purposes (discussed later in this report) under which to implement the repair work. The results of the study are published in a dam safety modification report, which is forwarded to division and headquarters officials, including the DSO, for review and approval of recommended repairs. The Corps districts are to communicate to sponsors and the public about dam failure risks and potential repairs during the study phase. Once approved by Corps’ DSO and ASA(CW), the cost estimate in the dam safety modification report is used as a basis to request funds from Congress for design and construction. Design: Project design takes place at the Corps districts and dam safety production centers, involving investigation of site conditions, such as testing soils, engineering analysis, and development of design plans and specifications. In addition, further risk analyses are to be conducted as well as expert reviews of the design. During the project’s design, the Corps districts are also to communicate to sponsors and the public about their plans for conducting repairs. Construction: Project construction, managed by district officials, is typically carried out through contracts with private companies. Construction for dam safety repairs can take multiple years and involve several contracts. To assure construction quality, the Corps districts are required to conduct regular inspections. In addition, Corps officials are to continue their outreach and communications with sponsors and the public throughout the construction period. Sponsors share in the costs of dam safety repairs based on original congressional authorizations for dam construction or subsequent sponsors’ agreements with the Corps. A wide array of entities can be cost sharing sponsors, including federal, state, and local agencies as well as private entities. Sponsors may be identified at the time of original dam construction or at a later time. Congressional authorizations or sponsors’ agreements with the Corps delineate the benefits sponsors receive as well as their responsibilities and cost sharing obligations. Cost sharing terms are unique to each sponsor at each dam. Commensurate with benefits derived from use of a dam, sponsors typically pay a percentage of a dam’s annual operations and maintenance costs, as well as the same percentage of total costs of major dam safety repairs. Cost sharing percentages can range from under 1 percent, such as for small water supply users, to over 50 percent, such as for hydropower users, depending on a sponsor’s agreement with the Corps. Sponsors’ payment mechanisms for dam safety repairs vary. When the Corps determines a need for dam safety repairs, it typically budgets for and funds the entire amount of the repair upfront. Sponsors, responsible for sharing in the design and construction costs for dam safety repair projects, pay their cost shares in different ways as described below and in table 1. However, not all Corps dams have cost sharing sponsors. The federal government fully funds the repairs of those Corps dams that do not have sponsors. Non-federal sponsors, depending on their agreement with the Corps, are to pay their cost share either on a “pay-as-you-go” basis or at the end of the project. Sponsors that are identified at the time of initial dam construction typically pay their cost share on a pay-as-you-go basis. In these situations, sponsors contribute their cost share while project design and construction are ongoing. Sponsors—typically water utilities—that enter into agreements with the Corps subsequent to the dam’s initial construction have the option to pay as you go or in lump sum, with interest, at the end of the dam safety repair project, once all costs are finalized and calculated. According to Corps officials, non-federal sponsors may seek an exception to amortize their cost share payments over time following project completion. The Corps collects and tracks payments submitted by non-federal sponsors and transmits them to the U.S. Treasury. Federal sponsors of Corps dams are the U.S. Department of Energy’s four Power Marketing Administrations (PMA). PMAs sell the electrical output of federally owned and operated hydroelectric dams. PMAs market wholesale power by entering into contracts with customers, with preference given to not-for-profit public-owned utilities, to sell power at set rates. Through their rates, PMAs recover all costs associated with power production and transmission, including their cost share for dam safety repairs, which they remit directly to the U.S. Treasury. PMAs are to recover all associated power production costs within a reasonable period of time, which the Department of Energy has traditionally considered to be 50 years or less. According to the Corps’ Safety of Dams regulation, during a dam safety modification study, Corps district officials are to identify and analyze all the potential ways that a dam could fail. Such potential failure modes can include: (1) embankment or foundation erosion through seepage; (2) inability of a dam to safely pass excess water during expected maximum flood conditions (hydrologic failure mode); or (3) inability of a dam to withstand the expected maximum earthquake (seismic failure mode). Once potential failure modes, among other things, are determined, Corps district officials are to generate a dam safety modification report that reviews alternatives and recommends a technical solution to address the potential failure modes. For cost sharing purposes, the regulation requires the district to recommend in the report one of the two types of cost sharing arrangements or authorities: Major Rehabilitation authority or Dam Safety Assurance authority. The potential failure mode is the primary factor in determining the applicable authority, in addition to consideration of policy and statutory requirements: Major Rehabilitation: According to Corps officials, this authority applies to dam safety repairs associated with typical degradation of dams over time. Under this authority, sponsors are to pay their full cost share. For example, if a sponsor’s agreed cost share is 10 percent, then the sponsor is responsible for 10 percent of the total cost of the dam safety repair project. (See table 2.)