Dams, reservoirs, and other infrastructure

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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 infrastructure for water supply and other purposes, the Colorado River system is unusual in both the ratio of reservoir storage to the annual average streamflow (about 4:1) and the fraction of the river’s total natural streamflow that is consumptively used (100% in most years).

Figure 1. Major dams, reservoirs, and water delivery projects in the Colorado River Basin, as listed in Tables 1-3. Image: Adapted from map by the Center for Colorado River Studies, Utah State University, based on original map by Reclamation)

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 water-supply storage (per the Reclamation teacup diagrams for the Upper and Lower basins).

By tradition and practice, the water supply and water use within the Gila River and other tributaries within Arizona have been excluded from that state's Colorado River water allocation and from tabulations of basinwide use and supply. Similarly, reservoir storage capacity in the Gila basin is generally excluded from tabulations of Colorado River system storage and system modeling, despite being within the physical Colorado River Basin. Most of the total capacity of about 5 maf in the Gila basin, 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
Roosevelt** Salt AZ Salt River Project (Reclamation) 1,653,000 36
Navajo San Juan NM/CO Reclamation 1,647,900 32
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 typically included in calculations of Colorado River system storage; **Not included in Reclamation's system models, or in 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 return flows (diversions minus consumptive use) have the potential for reuse.

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. The consumptive use can vary significantly from year to year; for Lower Basin projects see the Lower Basin Annual Water Accounting Reports. Data on the annual diversions for Upper Basin projects can typically be obtained from the relevant state water resources agency, but data on annual 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 (Duchesne 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 Lake Havasu AZ Central Arizona Project Tribes; M&I; Ag Main canal 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
Mexico: Reforma & Independencia Canals, Tijuana Aqueduct Morelos Dam Baja Calif. (MX) Dam: International Boundary Water Commission Ag, M&I All of Mexico’s water allocation is diverted at Morelos Dam; 100s of miles of aqueducts, canals, and laterals; Ag: 600,000 acres in Mexicali Valley; 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. Note that the information on these pages may not have been updated since the 1990s.

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. Note that the information in the pages may not have been updated since the 1990s.

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.