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).

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Figure 1. CAPTION. SOURCE.)

Dams and reservoirs

There are 15 major dams on the Colorado River mainstem, 8 of which impound reservoirs, and hundreds of dams and impoundments on the tributaries. Total reservoir storage capacity across the basin is about 67 million acre-feet (maf). The vast majority of this capacity, about 60 maf, is impounded by dams that are operated by Reclamation as a coordinated Colorado River system. Most of this system storage capacity is in Lake Mead (26 maf) and Lake Powell (23 maf).

Additionally, and mainly in the Upper Basin, there are hundreds of reservoirs operated by water districts, irrigation districts, and municipalities, with varying degrees of coordination with the Reclamation system. The total storage capacity of non-system Upper Basin reservoirs is about 2 maf. In the Lower Basin, the infrastructure operated separately from the Colorado River system is all in the Gila River basin, most of it operated by the Salt River Project. Total storage capacity in the Gila basin, excluding projects used solely for flood control, is about 5 maf. 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. Most of the basin’s water storage–and hydropower capacity–is at Lake Mead and Lake Powell.

Table 1. The 10 largest reservoirs within the Colorado River Basin. The reservoirs in italics are not part of the Colorado River system as managed by Reclamation, though their respective operations may be coordinated with Reclamation’s operations.

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

Major diversion and conveyance 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 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. Data for Upper Basin projects is more difficult to obtain; see the relevant state water resources agency.

Table 2. Major water conveyance projects in the Upper Basin. 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)

Additional resources

State of the Science Report

Chapter # of the State of the Science report, describes...