Dams, reservoirs, and other infrastructure
Overview
The natural channels and functions of the Colorado River and its tributaries have been overlain and modified by an enormous network of water infrastructure. Large dams and reservoirs are the most obvious elements of this infrastructure, which also includes canals, ditches, tunnels, pump stations, pipelines, and hydropower generation. While nearly all major rivers in the western U.S. have similar water supply infrastructure, the Colorado River system stands out in its ratio of reservoir storage to the annual average streamflow (about 4:1) and the amount of the river’s total natural streamflow that is consumptively used (100% in most years).
Dams and reservoirs
There are 8 major dams and reservoirs, and 7 diversion dams, on the Colorado River mainstem, and hundreds of dams and reservoirs the tributaries. Excluding the reservoirs in the Gila River Basin (as explained below), total storage capacity across the basin is about 62 million acre-feet (maf). About 80% of this system storage capacity is in Lake Mead (26.1 maf) and Lake Powell (23.3 maf), with the remainder spread across dozens of major reservoirs (>0.1 maf) and hundreds of smaller ones, primarily in the Upper Basin. Over 90% of the system storage capacity is held by dams owned and operated by Reclamation, or owned by Reclamation and operated by a cooperating agency. Table 1 lists the 10 largest reservoirs within the Colorado River Basin by capacity for water-supply storage only, not including the flood-control pool, if any.
By tradition and practice, if not universally agreed-upon legal basis, the water supply and water use within the Gila River and other tributaries within Arizona has been excluded from that state's Colorado River water allocation and from tabulations of basinwide use and supply. Similarly, the significant reservoir storage capacity in the Gila basin is generally excluded from considerations and tabulations of Colorado River system storage and system modeling, despite sitting within the physical Colorado River Basin. Of the total capacity of about 5 maf (excepting projects used exclusively for flood control), most is held behind dams operated by Salt River Project (Phoenix).
Table 1. The 10 largest reservoirs within the Colorado River Basin.
| Reservoir (Dam, if different name) | River | State | Dam Operator (Owner, if different) | Capacity (water-supply storage), AF | Hydropower installed capacity, MW |
|---|---|---|---|---|---|
| Mead (Hoover) | mainstem | NV/AZ | Reclamation | 26,100,000 | 2079 |
| Powell (Glen Canyon) | mainstem | UT/AZ | Reclamation | 23,314,000 | 1320 |
| Flaming Gorge | Green | UT/WY | Reclamation | 3,671,100 | 152 |
| Mohave (Davis) | mainstem | AZ/CA | Reclamation | 1,801,200 | 255 |
| Navajo | San Juan | NM/CO | Reclamation | 1,674,900 | 32 |
| Roosevelt** | Salt | AZ | Salt River Project (Reclamation) | 1,653,000 | 36 |
| Strawberry* (Soldier Creek) | Strawberry | UT | Central Utah WCD (Reclamation) | 1,105,900 | n/a |
| Blue Mesa | Gunnison | CO | Reclamation | 827,500 | 86 |
| Havasu (Parker) | mainstem | AZ/CA | Reclamation | 618,300 | 120 |
| Granby* | mainstem | CO | Northern Water & Reclamation (Reclamation) | 539,800 | 1 |
- Not included in Reclamation's system models, but generally considered to be part of Colorado River system storage
- Not included in Reclamation's system models or system storage
Major water delivery projects
In addition to thousands of individually operated ditches and canals that divert water from the mainstem and tributaries, there are a number of major water delivery projects or systems encompassing at some or all of the following: large canals (carrying 100-4000 cubic feet per second), pump stations, aqueducts, pipelines, tunnels, and reservoirs. Several of these major projects involve transbasin diversions, conveying water to uses outside of the Colorado River Basin; all water diverted to another basin counts as consumptive use (CU). Other projects distribute water within the basin, such that any return flows (diversions minus consumptive use) could potentially be reused by others in the basin.
Tables 2 and 3 list selected major projects in the Upper Basin and Lower Basin, respectively. Each project supplies an average of at least 100,000 acre-feet of consumptive use per year. Consumptive use can vary significantly from year to year; for Lower Basin projects see the annual Lower Basin Annual Water Accounting Reports. Annual diversion data for Upper Basin projects can typically be obtained from the relevant state water resources agency, but data on consumptive use may not be available.
Table 2. Major water delivery projects in the Upper Basin. Listed approximately in descending order of average annual consumptive use supplied by that project. Abbreviations for main uses: Ag = Agriculture; M&I = Municipal and industrial; Tribes = water to satisfy water allocations to one or more tribal nations–which could be used for Ag and/or M&I.
| Project | Primary diversion point | State | Operator (Owner, if different) | Main use(s) | Comments |
|---|---|---|---|---|---|
| Uncompahgre Project | Gunnison Tunnel north portal (Gunnison River) | CO | Uncompahgre Valley WUA | Ag | 6-mile tunnel, 128 miles of canals, 238 miles of laterals; also diverts local Uncompahgre R.; Ag: 70,000 acres |
| Grand Valley Project | Cameo Diversion Dam (mainstem) | CO | Grand Valley WUA (Reclamation) | Ag; M&I | 55-mile main canal, 35-mile secondary canal, 166 miles laterals; Ag: 40,000 acres; M&I: outdoor only; also supplies Orchard Mesa Power Plant (hydropower) |
| Grand Valley Canal | Diversion dam at Palisade (mainstem) | CO | Grand Valley Irrigation Co. | Ag | 100 miles of canals; Ag: 40,000 acres |
| Colorado-Big Thompson Project | Lake Granby (mainstem) | CO | Northern Water & Reclamation (Reclamation) | M&I, Ag | Transbasin; 130 miles tunnels and canals; M&I: Fort Collins, Greeley, Loveland, Boulder; Ag: 600,000 acres (supplemental supply) |
| Central Utah Project | Multiple (Duschene River basin) | UT | Central Utah WCD (Reclamation) | M&I, Ag, Tribes | Mostly transbasin, some water used locally; M&I: Salt Lake City, other Wasatch Front cities, Jensen |
| San Juan-Chama Project | Multiple (San Juan River basin) | NM | Reclamation | M&I, Ag, Tribes | Transbasin; 27 miles of tunnels, Heron Lake; M&I: Albuquerque, Santa Fe, Los Alamos; Ag: 90,000 acres (supplemental) |
Table 3. Major water delivery projects in the Lower Basin. Listed approximately in descending order of average annual consumptive use supplied by that project. See Table 2 for abbreviations for main uses.
| Project | Primary diversion point | State | Operator (Owner, if different) | Main use(s) | Comments |
|---|---|---|---|---|---|
| All-American Canal; Imperial Irrigation District | Imperial Dam | CA | Imperial ID (Reclamation) | Ag | 82-mile main canal, >1000 miles total canals; Ag: 470,000 acres. |
| Central Arizona Project Canal | Lake Havasu | AZ | Central Arizona Project | Tribes; M&I; Ag | 336 miles long; 14 pump plants; Tribes: 11 (includes both Ag, M&I) M&I: Phoenix area, Tucson; Ag: 350,000 acres; CAP water also used for groundwater recharge |
| Alamo Canal; Mexicali Valley | Morelos Dam | Baja Calif. (MX) | Dam: International Boundary Water Commission | Ag, M&I | All of Mexico’s CRB allocation is diverted at Morelos Dam; main canal feeds hundreds of miles of aqueducts, canals, and laterals; Ag: 600,000 acres; M&I: Mexicali, San Luis, Tijuana |
| Colorado River Aqueduct | Lake Havasu | CA | Metropolitan Water District of Southern CA | M&I | Transbasin; 242-mile aqueduct; 5 pump plants, 9 reservoirs; M&I: Los Angeles and San Diego metro areas |
| Gila Project | Imperial Dam | AZ | 5 Yuma-area water districts | Ag; M&I | Ag: 100,000 acres; M&I: Yuma |
| Palo Verde Diversion Project and Irrigation District | Palo Verde Dam | CA | Palo Verde ID | Ag; M&I | 244 miles of main canal and laterals; Ag: 100,000 acres; M&I: Fallowing program transfers water to MWD |
| Coachella Canal | Imperial Dam | CA | Coachella Valley Water District | Ag | Branches off All-American Canal; 123-mile canal w/ 500 miles of underground laterals; Ag: 60,000 acres |
| Salt River Project | Granite Reef Dam (Salt River) | AZ | Salt River Project (Reclamation) | M&I | Lake Roosevelt, six major canals, 1100 miles of canals, laterals and drains; M&I: Phoenix metropolitan area |
| Southern Nevada Water System | Lake Mead | NV | Southern Nevada Water Authority | M&I | Three intakes at Lake Mead, two pump stations; nearly all water used indoors is treated and returned to Lake Mead; M&I: Las Vegas metropolitan area |
Data and tools
Reclamation HydroData Reservoir Map
Provides map-based access to current and historical reservoir level, storage, inflows, and releases, for about 70 reservoirs within the basin or that store Colorado River water, including all of the 10 major reservoirs in Table 1 except for Roosevelt Lake.
Reclamation HydroData Gage Map
Provides map-based access to current and historical diversions and flows at over 20 points in the Upper Basin, including elements of the following projects: Central Utah, Uncompahgre, Grand Valley, and San-Juan Chama.
Reclamation Boulder Canyon Operations Office (BCOO) - Data Explorer
Provides map-based access to daily data for the diversions by major water users between Lake Mead and Mexico, including SNWA, MWD, CAP, Palo Verde, and the All-American Canal.
CWCB/DWR - Colorado’s Decision Support Systems (CDSS)
CDSS provides map-based access to daily and monthly data for about 150 diversion structures within Colorado’s portion of the CRB, including elements of the following major projects: Uncompahgre, Grand Valley, Grand Valley Canal, Colorado-Big Thompson.
Reclamation - Lower Basin Annual Water Accounting Reports (1964–2022)
These reports, covering only the Lower Basin, break down annual consumptive use by point of diversion, quantifying the water usage of the various water districts, irrigation districts, municipalities, and tribes, including the use associated with the major projects identified in Table 3.
Additional resources
Reclamation - Upper Colorado Region - Projects & Facilities
This page lists the several dozen projects, dams, and other facilities constructed, owned and/or operated by Reclamation within the Upper Basin, with each one linked to pages with information about that project or facility.
Reclamation - Lower Colorado Region - Projects & Facilities
This page lists the several dozen projects, dams, and other facilities constructed, owned and/or operated by Reclamation within the Lower Basin, with each one linked to an individual page with information about that project or facility. A similar homepage for Lower Basin projects and facilities links to the same set of individual project and facility pages, though from a slightly different overall list.
Babbitt Center for Land and Water Policy - Colorado River Basin Map
This highly detailed basin map, created in 2021, shows the locations of several dozen dams, canals, and aqueducts, including but not limited to the dams and projects in Figure 1 and Tables 1-3.