The Corps Water Management System (CWMS) includes four interrelated models to assist with water management for the basin:
- GeoHMS (Geospatial Hydrologic Modeling Extension)
- ResSIM (Reservoir System Simulation)
- RAS (River Analysis System)
- FIA (Flood Impact Analysis)
Within the South Platte basin, there are three USACE reservoir projects. All are located in or near the Denver metropolitan area. The projects are Cherry Creek Dam (on Cherry Creek), Bear Creek Dam (on Bear Creek), and Chatfield Dam (on the South Platte River). Their project purposes include flood control, recreation, and fish and wildlife. In addition, Chatfield Dam is authorized for water supply. Other water municipalities, namely Denver Water and Aurora Water, own and operate an intricate water infrastructure of, among other things, dams, diversions, canals, and water treatment plants.
A few of the notable tributaries to the South Platte River include Cherry Creek, Bear Creek, Tarryall Creek, Plum Creek, Clear Creek, Boulder Creek, St. Vrain River, Big Thompson River, and Cache la Poudre River. Though the following is not an exhaustive list, the key gages in the basin include Bear Creek at Morrison, Sheridan, and Denver; Cherry Creek at Franktown, Parker, and Denver; and South Platte at Waterton, Louviers, blw Chatfield, Denver, and Henderson.
During non-flood control operations, the three USACE reservoirs are operated based on water rights criteria provided to the Omaha District by the State of Colorado. In this case, Cherry Creek and Bear Creek release inflows, while Chatfield does have some authorized water supply storage. During flood control operations, the three reservoirs target the South Platte River at Denver, Colorado stream gage. The target maximum flow at this gage is 5,000 cfs. This would include both the reservoir releases and incremental flow. During flood control operations, there are provisions aimed at balancing the amount of flood control storage present in each of the three projects.
The South Platte watershed is mountainous in the western portion while the central and eastern portions are more indicative of the high plains. Average annual precipitation in the Denver metropolitan area is approximately 16 inches – with most of this coming as rain in the April to August timeframe. The mountains receive a variable annual snowpack with places exceeding 100 inches. Snowmelt, along with spring/summer rains, promotes the flooding concerns. Bear Creek and Chatfield watersheds are affected by the mountain snow while the Cherry Creek watershed lies in the high plains portion of the South Platte Basin.