Capital stock value represents the value a portfolio of infrastructure at any given point in time. The current USACE Capital Stock incudes all water resources infrastructure built by the USACE from 1928 to 2023. This infrastructure includes dams, levees, harbors and waterway improvements, locks, channels, hydroelectric generating works, and recreation facilities.

Within Fast Facts, the USACE capital stock value is determined using the Perpetual Inventory Method (PIM). The PIM method is a top-down approach that estimates the value of capital stock by calculating the cumulative value of investments over time while adjusting for asset retirements and losses in productive capacity caused by deterioration (i.e., normal wear and tear). Deterioration over time is modeled by a specified decay function.  The shape of this decay function (e.g., linear vs. hyperbolic) should reflect the simulated pattern of deterioration over time of the asset or group of assets being modeled. While a bottom-up method (i.e., calculating capital stock value at the asset/project level) would provide more accurate results, historical data of such a high resolution are not easily attainable.  And physically surveying the USACE capital stock at the asset level would be cost prohibitive. The basic PIM equation is as follows: