Located within the Department of Defense, the Corps has both military and civilian responsibilities. The Corps’ civil works program, which is responsible for water resources projects, is organized into three tiers: a national headquarters in Washington, D.C.; eight regional divisions that were generally established according to watershed boundaries; and 38 districts nationwide. Corps headquarters primarily develops the policies and guidance that the agency’s divisions and districts carry out as part of their oversight responsibilities of the water projects under the Corps’ purview. The Assistant Secretary of the Army for Civil Works, appointed by the President, establishes the policy direction for the civil works program. The Chief of Engineers, a military officer, oversees the Corps’ civil works operations and reports on civil works matters to the Assistant Secretary of the Army for Civil Works. The eight divisions, commanded by military officers, coordinate civil works projects in the districts within their respective divisions. Corps’ districts, also commanded by military officers, are responsible for planning, engineering, constructing, and managing water-resources infrastructure projects in their districts. The Corps also has a number of centers of expertise, with staff that provide specialized knowledge and skills for fulfilling the Corps’ responsibilities. One center of expertise is the Hydroelectric Design Center, located in the Corps’ Portland district, which provides hydroelectric and large pumping plant engineering services. Within the Hydroelectric Design Center is the Hydropower Analysis Center, which conducts analyses of hydropower projects and economic benefit evaluations for existing and new hydropower projects for all of the Corps’ power plant installations. The Corps enters into agreements with M&I water users, such as states or local water utilities, for water storage within Corps-managed projects, such as reservoirs or dams. According to a Corps report, as of December 2014, the majority of M&I water storage is concentrated in the Corps’ Southwestern division, which contains almost half of the Corps’ projects with M&I water supply storage, and over two-thirds of Corps M&I storage by volume. The next highest concentration of projects with M&I storage is in the Corps’ Great Lakes and Ohio River division, with approximately one-fifth of Corps projects and just over 5 percent of storage volume (see fig. 1). The Corps provides M&I water storage but does not have a role in acquiring or securing the rights for water that users store at Corps’ projects. Water users must secure the necessary water rights. The Corps also does not have a substantial role in the distribution of stored water, which is generally the responsibility of water users. Figure 2 shows the key stages, including the Corps’ role, in the M&I water storage process. The Water Supply Act of 1958 authorizes the Corps to provide M&I water storage at federal projects owned and operated by the Corps to water users on a reimbursable basis. Under this act, a water user is to reimburse the Corps for the costs associated with the user’s share of the storage costs. Water users do so by entering into “repayment” agreements with the Corps. The Water Resources Development Act of 1986 amended the Water Supply Act of 1958 by changing the repayment period for water storage agreements from 50 years, as established in the 1958 act, to 30 years. It also provided that the terms of repayment for M&I water storage agreements signed after 1986 be recalculated every 5 years, using an interest rate current at the time of recalculation, and required that O&M costs be reimbursed annually. See figure 3 for a timeline of key statutes that establish the Corps’ water storage authorities. Under the Water Supply Act of 1958, water users may enter into one of two types of M&I water storage agreements: originally authorized and reallocation. According to Corps officials, under both types of agreements, water users approach the Corps to request a water storage agreement and are to demonstrate that they have secured the necessary water rights under state law. Under the act, the Corps may enter into originally authorized agreements for water supply that were included in storage plans prior to the construction of the project, pursuant to specific congressional authorization. Since the 1990s, however, construction of new projects has slowed significantly, resulting in fewer originally authorized agreements. According to Corps officials, the last projects with originally authorized M&I water storage were constructed in 1991. As shown in figure 4, to initiate an originally authorized water storage agreement, an M&I water user typically approaches the Corps. The Corps district calculates the cost of storage and drafts a water storage agreement. The Corps has a standard agreement template it generally uses for originally authorized water storage agreements. The Corps’ division reviews the water storage agreement when it uses the standard agreement template. In cases where the water storage agreement exceeds 1,000 acre-feet of storage space or contains significant modifications from the standard template, review and approval by Corps headquarters officials is needed. The Corps manages water storage projects that have a variety of uses such as storage for flood control, hydropower, and irrigation. For illustrative purposes, the figure depicts such uses as use #1 and use #2. In addition, Corps projects store millions of acre-feet of water for M&I purposes. Originally authorized M&I water storage agreements are agreements for water supply that were included in storage plans prior to the construction of the reservoir. The inactive pool is the lowest storage area. Water in the inactive pool would only be used during extreme droughts or emergencies. Dashed lines are not physical separations. The lines are used to indicate increases and decreases in the storage volume of existing uses within the reservoir as a result of an originally authorized M&I water storage agreement. Under the Water Supply Act of 1958, the Corps also may reallocate or reassign water storage at an existing project (e.g., reservoir) from one use to another, such as reallocating storage for hydropower generation to M&I water supply. The act prohibits the Corps from reallocating storage in a manner that would seriously affect the project purposes or that would involve major structural or operational changes without congressional approval. Since the mid-1980s, the Corps has increasingly entered into reallocation agreements to provide M&I water storage. According to a Corps report published in 2015, the Corps entered into over 30 reallocation agreements from the 1950s through the 1980s and over 130 originally authorized agreements. From 1990 through December 2014, the Corps entered into approximately 100 reallocation agreements and just under 50 originally authorized agreements. According to Corps officials, to initiate a reallocation agreement, a prospective M&I water user typically submits a request to the Corps, as shown in figure 5. Before entering into a reallocation agreement, the Corps is to review the status of the project in its dam safety program and determine if a reallocation can be undertaken without unacceptable risks to public safety. If the project is approved and funded, the Corps conducts a reallocation study to determine the feasibility of the proposed reallocation, significance of project modifications and effects on other authorized purposes, and the size and cost of the water storage reallocation needed to meet the water user’s request. Corps officials at the district, division, and headquarters levels conduct analyses or review reallocation studies; these officials may include engineers, economists, environmental scientists, attorneys, and project managers. In addition, officials with specialized knowledge, such as from the Corps’ centers of expertise, may also contribute to a reallocation study by providing technical assistance. The level of approval necessary within the Corps depends on the size and impact of the M&I water storage reallocation. If the reallocation will require major structural or operational modifications to the project or seriously affect authorized project purposes, the Water Supply Act of 1958 requires that Congress approve the reallocation study recommendations. Once congressional approval is obtained, the Assistant Secretary of the Army for Civil Works is to approve the agreement. When the reallocation does not require major structural or operational modifications to the project or seriously affect authorized project purposes, the Assistant Secretary of the Army for Civil Works approves the resulting reallocation agreement. The Assistant Secretary of the Army for Civil Works is to review and approve the first M&I water storage agreement at any project. Otherwise, the Assistant Secretary of the Army for Civil Works has delegated authority to Corps headquarters to approve agreements when the total amount of storage space reallocated for a project for M&I water does not exceed the lesser of 15 percent of the total storage capacity of the project or 50,000 acre-feet. Corps headquarters has further delegated approval authority to division commanders for water storage up to 499 acre-feet and to district commanders for up to 99 acre-feet. Both types of water storage agreements generally specify either that the water user is to repay (1) as a lump sum the first costs, such as costs for relocations, engineering, and design, associated with M&I storage at the time the agreement is enacted; or (2) over time for a period of up to 30 years with interest. According to Corps guidance, in the case of originally authorized agreements signed after 1986, the repayment period may not extend beyond 30 years from the date when the project was completed and placed in service or the date the first M&I water storage agreement for the project was signed, whichever is later. According to Corps officials, because most water storage projects were completed before 1980, there are few projects with originally authorized storage space that may still amortize the repayment of new agreements. In the event that repayment of originally authorized storage can be amortized, the Corps uses the current interest rate established under the Water Supply Act of 1958 and recalculates, accordingly, the terms of repayment every 5 years. Any water user with an active M&I storage agreement approved after the Water Resources Development Act of 1986 is to repay a percentage of the relevant project’s annual O&M costs to the Corps.