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)
The climate of the upper part of the Truckee River Basin is characterized by severe winters and short, mild summers. Precipitation is markedly less than on the western slopes of the Sierra Nevada. The climate of the lower portion of the basin is typical of the Great Basin. The winters are long but with deficient precipitation, and the summers are short with practically no precipitation. Normal annual precipitation over the drainage area between Lake Tahoe and Reno varies from 8 to 70 inches, with a basin mean of 26.5 inches. Precipitation usually falls as snow above elevation 5,000 feet, but some storms produce rain up to the highest elevations of the basin, and snowfall may occur anywhere in the basin. Precipitation in the headwater areas of the Truckee River Basin usually is associated with general storms which occur during the winter season of November through April. These storms originate over the Pacific Ocean and must cross the continuous barrier of the Sierra Nevada, which averages 8,000 feet in elevation, to reach these areas. Storm periods last from 1 to 4 days.

Major storms that have occurred over the Truckee River Basin since include those of December 1955, January 1963, and December 1964, February 1986, and January 1997. Local cloudbursts occur frequently during the summer. They usually occur in July and August when warm, mosit air is more likely to reach this area of Nevada from the Gulf of California. These storms are characterized by high intensities over small areas and can produce large flood flows on the smaller tributary streams but do not have a major impact on flow in the Truckee River. Most of the runoff from the Truckee River Basin occurs from November through July. In general, runoff from November through March results from rains that may extend to an elevation of 9,000 feet, and runoff from April through July usually results from snowmelt.
In the area between Lake Tahoe outlet and Reno, the flood plain consists of a comparatively narrow strip immediately adjacent to the stream, where damages are limited to railroad and highway facilities, diversion dams, canals and aqueducts and other types of public and private utilities. Some minor residential damage to cabins and summer homes has been experienced along the river principally between Lake Tahoe and Truckee.

The flood plain of the Truckee Riverr downstream of Vista consists prirnarily of agriculturral lands contiguous to the river channel. In the city of Reno and vicinity, the area subject to flooding include extensive and diversified property and improvements that are characteristic of the central portion of a prosperous urban development. In the Sparks-Truckee Meadow area considerable urban development and construction of light industry and warehousing has taken place. The Truckee River channel and overbank capacities through Reno are limited to a flow of 12,000 cfs in Reno and 6,000 cfs within Sparks. When these capacities are exceeded water leaves the overbank area and flows in a southeasterly direction eventually combining with other runoff in the Truckee Meadows area. Street and bridge elevations are approximately the same as the river bank elevations, and widespread flooding results when flood waters run overbank. The flood problem in Reno is further aggravated by floating debris which accompanies large floods.