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The All-American Canal System, located in the southeastern corner of California, consists of the Imperial Diversion Dam and Desilting Works, the 80-mile-long All-American Canal, the 123-mile-long Coachella Canal, and appurtenant structures. The system has the capacity, through water diversions from the Colorado River at Imperial Dam, to provide irrigation water for nearly 600,000 acres of land in the Imperial and Coachella Valleys. No power is developed on the system by the Federal Government. The Imperial Irrigation District (IID), which operates the All-American Canal, has constructed small hydroelectric powerplants at several locations along the canal to provide electricity throughout the IID service area. The 8,000 acre-foot Brock (Drop 2) Storage Reservoir was constructed near the canal in 2008-2010 to provide additional storage capacity to reduce non-storable flows on the Colorado River below Parker Dam.
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Irrigation water is diverted from the Colorado River at Imperial Dam through desilting basins into the All-American Canal on the California side and the Gila Gravity Main Canal on the Arizona side. These two canals and the canals that branch off from them carry water to their respective project areas, where the water is then delivered to the lands through distribution systems.
Imperial Dam and Desilting Works are situated on the Colorado River 18 miles northeast of Yuma, Arizona. The purpose of the dam is to raise the water surface 25 feet and provide controlled gravity flow of water into the All-American and Gila Gravity Main Canals. The desilting works remove most the sediment carried by the Colorado River, an activity that prevents silt from clogging the canals and subsequent, expensive, difficult maintenance.
To meet the irrigation diversion requirements at Imperial Dam, Colorado River water is released from Parker Dam, 150 miles upstream.
Located approximately two miles upstream of Imperial Dam, on the California side of the Colorado River, is Senator Wash Dam, Reservoir, and Pump-Generating Plant. Senator Wash facilities are not part of the Boulder Canyon Project or the All-American Canal System, but are an integral part of operations at Imperial Dam. Senator Wash is an offstream regulating reservoir. When flows arriving at Imperial Dam exceed diversion demands, water can be pumped from the Colorado River into Senator Wash Reservoir and released at a later date when demands are greater than the flow arriving at Imperial Dam.
The reservoir created by Imperial Dam initially had a capacity of 85,000 acre-feet. This storage capacity was not considered a project feature and, as anticipated, the reservoir quickly filled with sediment. The reservoir capacity is now estimated to be about 1,000 acre-feet, and intermittent dredging is required to maintain required diversion capacity at the Gila Gravity Main Canal.
Imperial Dam is a reinforced concrete structure of the monolithic slab-and-buttress type. It consists of an overflow weir, canal headworks at each end of the dam, and a sluiceway between the All-American Canal Headworks and the overflow weir. The dam is 3,475 feet long, including a 490-foot rockfill dike at the Arizona end. The overflow weir is 1,197.5 feet long and designed to pass a flow of 142,000 cubic feet per second. The overflow weir, in conjunction with the California Sluiceway, is designed to pass a maximum flood of 180,000 cubic feet per second, not including any diversions to the canal systems.
The two canal headworks are equipped with trashracks to prevent large pieces of debris from entering the canal systems. Trash removal is accomplished by an electrically powered rake device which pulls the trash up and dumps it into small, rail-mounted cars. The cars are moved to a chute where the trash is dumped into a truck and hauled to a disposal site where it is either burned or buried.
The designs of the desilting works for the All-American and Gila Gravity Main Canals are significantly different. The Gila facility consists of a concrete-lined basin. When water flows into the basin, sediment settles to the bottom while clear water is skimmed off the top as flows pass over the diversion control gates into the Gila Gravity Main Canal.
The All-American Canal Desilting Works are more elaborate. The flow into the canal is controlled at the headworks before the water passes through the desilting works rather than after, as at the Gila facility. The headworks consists of four roller gates, each 75 feet long and 22 feet high, including apron and flash weir. Downstream from the roller gates are four concrete channels with vertical concrete walls between the channels. Three of the channels carry water to the three existing desilting basins. The fourth channel was constructed to serve a fourth basin, and is used as a bypass channel, if needed. All four channels are equipped with gates to permit water to bypass the basins through outflow channels when necessary. The three basins are separated into halves by a long tapered channel through which water enters the basin, with the vertical slots along the sides designed to evenly distribute water. The water flows across each basin half at a low velocity, allowing the sediment to settle to the bottom where it is moved by rotating scrapers to a central pedestal containing a rotating mechanism and piping system. The pipe system under each basin discharges the collected sediment, along with the necessary water to move it, into the California Sluiceway. The clear water near the surface flows over weirs and into channels leading to the All-American Canal.
The California Sluiceway extends about 3,000 feet downstream from the 12 radial gates located between the All-American Canal Headworks and the overflow weir. As sediment collects in the sluiceway, it is moved downstream by high rate, short duration (sluicing) flows of water discharged through the sluiceway gates. The sluicing flows usually are 12,000 cubic feet per second released for a 20-minute period, although many different flow rates, time periods, and combinations of gates are used. This procedure also removes some sediment from Imperial Dam Reservoir.
Prior to 1964, the sediment from the desilting basins found its way down the river and a disproportionate amount entered the Mexican irrigation system as water was diverted from the Colorado River. To resolve this problem, a 4-mile-long channel was constructed in 1964 from the end of the California Sluiceway to the reservoir area above Laguna Dam. A large settling basin was excavated about midway in this channel to collect the sediment moved out of the sluiceway. Dredges pump the sediment from the settling basin to the adjacent floodplain; the first dredging operation started in 1965 and has since been intermittently required about every 2 years.
The sluicing flows from Imperial Dam are stored behind Laguna Dam and released over extended periods. Laguna Dam releases to become part of the water delivered to Mexico.
The California Sluiceway is also used to discharge excess water flows arriving at Imperial Dam that are not pumped to Senator Wash Reservoir or diverted to the canals. It is preferred to keep water from passing over the overflow weir to prevent damage to roads and other facilities immediately below Imperial Dam.
The All-American Canal serves the Imperial and Coachella Valleys in southern California and the Yuma Project in California and Arizona. The canal has a design carrying capacity of 15,155 cubic feet per second from the desilting works to Siphon Drop, 14.7 miles downstream. From Siphon Drop, the capacity reduces to 13,155 cubic feet per second for another 6 miles to Pilot Knob. The capacity of the canal is 10,155 cubic feet per second for the next 15.5 miles to Drop No. 1 where the Coachella Canal starts.
From Drop No. 1, the canal continues west, parallel to the Mexican border for another 44 miles, gradually reducing in capacity from 7,755 to 2,655 cubic feet per second. At this point, the canal connects with the Westside Canal about 10 miles west of Calexico, California (about 80 miles from Imperial Dam). The design capacity of the All-American Canal included 155 cubic feet per second for the City of San Diego, California; however, the San Diego diversion point was changed from Imperial Dam to a point above Parker Dam in 1946.
Water is diverted from the All-American Canal to most of the Reservation Division of the Yuma Project in California at four turnouts between the Laguna Dam area and Siphon Drop. A turnout at Siphon Drop diverts water to the Yuma Main Canal for the Valley Division of the Yuma Project in Arizona plus some areas of the Reservation Division.
Pilot Knob facilities include a powerplant and wasteway. Much of the water required to meet Mexican treaty requirements is diverted from the Colorado River at Imperial Dam into the All-American Canal and is returned to the Colorado River through Pilot Knob Powerplant, generating electricity in the process. The Pilot Knob Wasteway automatically discharges water from the All-American Canal if the canal elevation becomes too high. After it is returned to the river, the water is diverted and delivered to Mexico at that country's Morelos Dam. The remaining water required to meet the Treaty obligations is collected from drains, canals and the Protective and Regulatory Pumping Unit ("242") well fields (operated as a feature of the Colorado River Basin Salinity Control Project, Title I), and delivered to Mexico at the Southerly International Boundary near San Luis, Arizona.
Hydroelectric powerplants at Drops 1, 2, 3, 4, 5 and at the East Highline canal turnout on the All-American Canal generate power for the Imperial Irrigation District. The amount of power generated fluctuates in accordance with the amount of water flowing through the canal. To maximize power production, the canal generally is operated with the highest water level possible.
In 1988, P.L. 100-675 authorized the Secretary of the Interior to construct a parallel lined canal or to otherwise recover the seepage from the earthen All-American Canal. The law prohibited the use of Federal funds for the project, but authorized the use of contributed funding from California agencies entitled to use Colorado River water. In April 1994, Reclamation and the Imperial Irrigation District completed a Final Environmental Impact Statement/Environmental Impact Report (EIS/EIR) that analyzed various alternatives to implement the law. The Record of Decision (ROD) for the project, signed July 29, 1994, selected construction of a 23-mile parallel canal as the means to conserve approximately 67,700 acre-feet of seepage each year.
Non-federal funding for implementation of the project was unavailable, and agreements on funding sources and the allocation of the water that would be conserved remained unresolved for several years after the execution of the ROD. As a result of the intensive effort by California to limit its use of Colorado River water to its legal apportionment of 4.4 million acre-feet per year, a series of agreements were signed in 2002 and 2003, and funding for the canal lining project was authorized by the California Legislature in September 2003. Final designs for the project were initiated in 2004 and largely completed in January 2006.
In early 2006, the Department of the Interior re-examined and analyzed the Final EIS/EIR for the canal lining to determine whether it and the ROD continued to meet National Environmental Policy Act requirements, or if a supplemental EIS/EIR was needed. The review determined there had been no substantial project changes or new circumstances relevant to the environmental resource areas addressed in the 1994 document, and a report was issued with the conclusion that no supplemental EIS/EIR was required.
In December 2006, Congress enacted and the President signed into law the Tax Relief and Health Care Act of 2006, Public Law 109-432. The Act provided that: ". . .Notwithstanding any other provision of law, upon the date of enactment of this Act, the Secretary (of the Interior) shall, without delay, carry out the All-American Canal Lining Project identified - (1) as the preferred alternative in the Record of Decision for that project, dated July 29, 1994; and (2) in the allocation agreement allocating water from the All-American Canal lining project, entered into as of October 10, 2003." The Act also provided that: "The Treaty between the United States of America and Mexico relating to the utilization of waters of the Colorado and Tijuana Rivers and of the Rio Grande, and supplementary protocol signed November 14, 1944, signed at Washington February 3, 1944 (59 Stat. 1219) is the exclusive authority for identifying, considering, analyzing, or addressing impacts occurring outside the boundary of the United States of the works constructed, acquired, or used within the territorial limits of the United States."
With financing from a California State bond and from the San Diego County Water Authority, the IID began construction of the lined canal in June 2007. With the majority of the work completed, the new section was dedicated on April 20, 2009; full completion of the project is not expected until early 2010.
The water conserved by the lining project will be used to settle Tribal water rights and to help California eliminate its historic reliance on surplus water from the Colorado River.
The Coachella Canal branches north off the All-American Canal at Drop 1, approximately 36 miles west of Yuma, Arizona. The Coachella Canal proceeds in a northwesterly direction for 123 miles on the east side of the Salton Sea to the Coachella Valley. The original canal,which began delivering water in 1949, had a capacity of 2,500 cubic feet per second.
For its first 89 miles, the Coachella Canal was an earthen canal; the final, northernmost 37 miles of the canal were lined with concrete when this section was built. Shortly after the canal's completion in 1948, seepage losses developed in the initial 86 miles, with the most severe seepage occurring in the canal's intial 49 miles, which traversed the coarse, sandy soils of the Imperial East Mesa. From 1955-1970, the average seepage loss in this 49-mile section of the canal was 140,000 acre-feet per year, or 28.3 percent of the canal's total flow.
In 1974, through the Colorado River Basin Salinity Control Project (Title I, Public Law 93-320, June 24, 1974), Congress provided for lining the first 49 miles of the canal with concrete to recover approximately 132,000 acre-feet of the water that was being lost by seepage. To maintain water deliveries during construction and avoid wet areas caused by seepage, a separate canal running nearly parallel to the original unlined section was designed. Construction of this new canal section began in 1979; it was completed and put into operation in late 1980. The project was funded by the Federal government, and the conserved water helps meet the United States' Colorado River water delivery treaty obligation to Mexico.
In 1988, Reclamation experimented with a then state-of-the-art method of lining canals. Called in-place lining, the process allows a canal to be lined with polyvinyl chloride (PVC) and concrete while water is still flowing in the canal. Work began on the lining of 1.4 miles of the canal in August 1988, and was completed in April 1991.
The remaining 35 miles of earthen canal were replaced with a parallel, concrete canal between 2004 and 2006. This work was funded by the State of California and the San Diego County Water Authority, and resulted in additional water conservation of about 26,000 acre-feet of conserved water per year that is used to meet urban needs in San Diego County as well as some of the water needs of the San Luis Rey Indian Tribe.
Today, the Coachella Canal's maximum carrying capacity is 1,300 cubic feet per second (the original unlined canal had a capacity of 2,500 cubic feet per second), although the volume of water delivered annually to the Coachella Valley Water District has not changed.
The Bureau of Reclamation also designed and constructed much of the Coachella Valley Water District`s original distribution system, which is mostly underground. The system consists of about 500 miles of gravity flow concrete pipelines, with a few small pumping plants serving the higher areas.
Protective floodworks were also constructed along the east side of the Coachella Valley to protect the main canal and distribution system from possible storm damage. Completed in 1949, these works consisted of two detention dikes along the canal and three wasteways to carry floodwaters impounded by the dikes to natural drainage channels. A rehabilitation and betterment program, completed in 1977, added a remote control system, terminal regulating reservoir, additional flood control structures, de-mossing screens, and other improvements.
Between 2008 and 2010, the Bureau of Reclamation constructed an 8,000 acre-foot storage reservoir near Drop 2 on the All-American Canal in southern California. (See Plan Photo here.)
The new reservoir stores Colorado River water that has been released from Parker Dam to meet downstream water orders but cannot be delivered for various reasons, such as changed weather conditions, high runoff into the river, or a number of other factors. This water typically is not put to beneficial use within the United States due to the lack of sufficient storage capacity below Parker Dam.
Reclamation and lower Colorado River basin water users had for some years considered various operational strategies to address these non-storable flows, which average about 70,000 acre-feet annually. In 2005, in cooperation with Imperial Irrigation District, Coachella Valley Water District, San Diego County Water Authority and Metropolitan Water District of Southern California, Reclamation completed a study that identified several potential alternatives to address this issue; this project was the preferred option.
In December 2006, Section 396 of Public Law 109-432 directed Reclamation to "design and provide for the construction, operation and maintenance of a regulated water storage facility ... at or near the All-American Canal."
The reservoir now provides:
Brock Reservoir History/BackgroundThe waters of the Colorado River are shared by 7 Western States and the Republic of Mexico. A complex series of legislation, treaties and agreements divides the Colorado River's water among the states and between the United States and Mexico.Each year, approximately 6 million acre-feet of Colorado River water is regulated at Imperial Diversion Dam, just north of Yuma, Arizona, for irrigation and other uses in California, Arizona and Mexico. That water must be released from storage in Lake Mead, nearly 300 miles to the north.It takes around five days for water released from Lake Mead to reach Imperial Dam (or approximately three days from Parker Dam to Imperial Dam). By the time the water arrives at Imperial Dam, the water users that scheduled it may not be able to put it to beneficial use due to changed weather conditions, high runoff into the river, or a number of other factors. Unless there was a way to store this unneeded water, it could not be put to beneficial use within the United States.Some of this water can be stored in Senator Wash Reservoir, a pumped-storage facility about two miles upstream from Imperial Dam. Senator Wash Dam was constructed specifically to manage fluctuating flows at the lower end of the Colorado River, but the storage capacity of this facility is limited. Water that could not be diverted at Imperial Dam or stored in Senator Wash Reservoir is called "non-storable" water.Between 2000 and 2009, more than 900,000 acre-feet of non-storable Colorado River water flowed to Mexico. That was in addition to more than 600,000 acre-feet of water from the Wellton-Mohawk Irrigation and Drainage District that bypasses the Colorado River and was discharged to the Cienega de Santa Clara in Mexico. To address this situation, the Bureau of Reclamation and Lower Colorado River Basin stakeholders in Arizona, California, and Nevada conducted a study to identify additional regulatory storage opportunities below Parker Dam. The study determined that building a small reservoir near the All-American Canal in Imperial County, California, was the best alternative to meet the objectives for conserving Colorado River water.Reclamation managed the construction of this additional regulating reservoir along the All-American Canal in southern California (Drop 2 Storage Reservoir). The 8,000 acre-foot reservoir roughly doubled the regulatory storage capacity on the lower Colorado River.Improved regulatory storage above the Mexican border saves on average 70,000 acre-feet of Colorado River water each year. The Lower Colorado River Basin states of Nevada, Arizona, and California, will fund construction and, in return for their investment, will receive a specific amount of additional water. The remainder of the saved water accrues to the river system.Brock Reservoir Frequently Asked QuestionsWhat is the Drop 2 Storage Reservoir Project?It is a system efficiency project that helps conserve Colorado River water that would otherwise not be put to beneficial use in the United States. Conserving this water and making it available to users in the United States reduces the amount of water that must be released from storage at Lake Mead. It consists of an all-gravity, off-stream storage reservoir system located north of the All-American Canal and Interstate 8 near Drop Structure No. 2, about 30 miles east of El Centro, CA, and 25 miles west of Yuma, AZ. It is not part of the All-American Canal Lining Project. What is the project’s purpose?The project supports conservation of water by capturing non-storable flows resulting from operational mismatches that occur in the Lower Colorado River Basin, and subsequently makes those flows available for users in the United States. (Non-storable flows are defined as those flows that cannot be captured and stored for later use.) At times, users downstream of Parker Dam reduce or cancel their water orders when rain events or other circumstances change their water needs. Depending on operational circumstances at the time, the water could not always be stored for later use. Because there was limited storage capacity below Parker Dam, primarily at Senator Wash Reservoir north of Yuma, some or all of the water that is ordered but not taken is non-storable. These non-storable flows average 70,000 acre-feet per year. Generally, this water flows into Mexico at Morelos Dam but does not count toward the United States’ annual water delivery requirement to Mexico, pursuant to the 1944 Treaty between the United States and Mexico. In 2005, the Bureau of Reclamation, in collaboration with multiple stakeholders, completed a study which identified several potential alternatives to address this issue; the Drop 2 (Brock) Storage Reservoir Project was the preferred option. In December 2006, Section 396 of Public Law 109-432 directed the Secretary of the Interior, “notwithstanding any other provision of law and without delay” to “design and provide for the construction, operation, and maintenance of a regulated water storage facility ... at or near the All-American Canal.” How does it work?Non-storable water from the Colorado River is diverted into the All-American Canal at Imperial Diversion Dam, then into the Drop 2 (Brock) Storage Reservoir. The water is then released back into the All-American Canal for delivery to and use by the Imperial Irrigation District according to an approved operations plan. What are the project’s key features?They are: an 8,000 acre-foot capacity reservoir comprised of two 4,000-acre-foot capacity storage cells; a diversion structure from the All-American Canal; a 6-1/2 mile-long inlet canal to carry diverted water to the reservoir; and a 1/4 mile-long canal/siphon system to take the water from the reservoir back to the All-American Canal just downstream of Drop 2. What is the project’s estimated cost? How was it funded?The estimated construction cost was $172 million. In response to drought conditions in the Lower Colorado River Basin, the Secretary of the Interior has adopted interim guidelines for Lower Basin shortages and coordinated operations of Lake Powell and Lake Mead. These guidelines allow Colorado River water contractors in the lower basin to contribute capital for use in Interior projects designed to create a more efficient water management system by conserving water that would otherwise be lost from the Colorado River mainstream in the United States. The guidelines also allow the Secretary to make available to these contractors an amount of water equal to a portion of the water projected to be conserved over a the life of the project, and to release this water to the contributing contractors on a pre-determined schedule of annual deliveries for a specified period of years. The Drop 2 Storage Reservoir Project is a system efficiency project. The Southern Nevada Water Authority (SNWA) agreed to pay most of the project's cost (including the cost of construction of the confluence structure of the project), as well as its operation and maintenance costs for a specified period of time. In return, SNWA will receive 400,000 acre-feet of water, at a maximum of 40,000 acre-feet a year, until 2036. The Central Arizona Water Conservation District (CAWCD) provided $28.6 million for construction of the project. In return, CAWCD will receive 100,000 acre-feet of water, at maximum of 65,000 acre-feet a year, from 2016 through 2036. (This amount is reduced by the amount of water used by SNWA and/or the Metropolitan Water District of Southern California in any given year.) The Metropolitan Water District of Southern California also participated in the project at the same funding level for the same amount of water as CAWCD. Who constructed the project and what was the construction schedule? The Bureau of Reclamation managed the construction which began in fall 2008, and was completed in 2010.
Brock Reservoir History/Background
The waters of the Colorado River are shared by 7 Western States and the Republic of Mexico. A complex series of legislation, treaties and agreements divides the Colorado River's water among the states and between the United States and Mexico.
Each year, approximately 6 million acre-feet of Colorado River water is regulated at Imperial Diversion Dam, just north of Yuma, Arizona, for irrigation and other uses in California, Arizona and Mexico. That water must be released from storage in Lake Mead, nearly 300 miles to the north.
It takes around five days for water released from Lake Mead to reach Imperial Dam (or approximately three days from Parker Dam to Imperial Dam). By the time the water arrives at Imperial Dam, the water users that scheduled it may not be able to put it to beneficial use due to changed weather conditions, high runoff into the river, or a number of other factors. Unless there was a way to store this unneeded water, it could not be put to beneficial use within the United States.
Some of this water can be stored in Senator Wash Reservoir, a pumped-storage facility about two miles upstream from Imperial Dam. Senator Wash Dam was constructed specifically to manage fluctuating flows at the lower end of the Colorado River, but the storage capacity of this facility is limited. Water that could not be diverted at Imperial Dam or stored in Senator Wash Reservoir is called "non-storable" water.
Between 2000 and 2009, more than 900,000 acre-feet of non-storable Colorado River water flowed to Mexico. That was in addition to more than 600,000 acre-feet of water from the Wellton-Mohawk Irrigation and Drainage District that bypasses the Colorado River and was discharged to the Cienega de Santa Clara in Mexico.
To address this situation, the Bureau of Reclamation and Lower Colorado River Basin stakeholders in Arizona, California, and Nevada conducted a study to identify additional regulatory storage opportunities below Parker Dam. The study determined that building a small reservoir near the All-American Canal in Imperial County, California, was the best alternative to meet the objectives for conserving Colorado River water.
Reclamation managed the construction of this additional regulating reservoir along the All-American Canal in southern California (Drop 2 Storage Reservoir). The 8,000 acre-foot reservoir roughly doubled the regulatory storage capacity on the lower Colorado River.
Improved regulatory storage above the Mexican border saves on average 70,000 acre-feet of Colorado River water each year. The Lower Colorado River Basin states of Nevada, Arizona, and California, will fund construction and, in return for their investment, will receive a specific amount of additional water. The remainder of the saved water accrues to the river system.
Brock Reservoir Frequently Asked Questions
What is the Drop 2 Storage Reservoir Project?
What is the project’s purpose?
How does it work?
What are the project’s key features?
What is the project’s estimated cost? How was it funded?
Who constructed the project and what was the construction schedule?
The All-American Canal below Pilot Knob was transferred to the Imperial Irrigation District for operation and maintenance on March 1, 1947. The District assumed responsibility on May 1, 1952, for those works above Pilot Knob including the All-American Canal Headworks, desilting basins, and the first 49 miles of the Coachella Canal. On December 7, 1982, the operation and maintenance of Laguna Dam, all Senator Wash facilities, and the remainder of Imperial Dam were transferred to the District.
The upper 74 miles of the Coachella Canal and protective works were transferred to the Coachella Valley Water District on March 25, 1949, for operation and maintenance. The distribution system in the Coachella Valley was transferred to this district in 1954. On November 1, 1982, following the replacement of the intial 49 miles of the canal with a new, concrete-lined section, this portion of the canal was also transferred to the District for operation and maintenance.
The Imperial Valley lies between the U.S.-Mexico border and the Salton Sea, bounded on the east by sandhills and on the west by the foothills of the San Diego Mountains.
Coachella Valley is located in the Salton Sea Basin. It lies partly in Riverside County and partly in Imperial County, California. The valley is surrounded on all sides except the south by mountains and is about 50 miles long, 1 mile wide at the northern end, and 11 to 12 miles wide in the center. Groundwater is present, and before the Coachella Canal was constructed, the land was irrigated with water from private wells.
In 1853, interest was aroused in the possibility of irrigating these lands with water from the Colorado River. In 1859, the California legislature asked Congress to cede 3 millions acres to the State of California for reclamation by irrigation. The Public Lands Committee of the House of Representatives acted favorably on this application, but in 1862 the bill failed to pass. The route proposed for the canal was practically the same as that used 40 years later for the Alamo Canal.
The Colorado River Irrigation Company, formed in 1891-1892, carefully examined the problem of irrigating the Colorado River delta and worked out important features to accomplish this goal, but financial difficulties brought about failure of this company. The California Development Company, formed in 1896, succeeded where the original company had failed and construction was begun in 1900.
The California Development Company constructed the first project to irrigate Imperial Valley, the Alamo Canal. It first delivered water to the valley in June 1901. The canal delivered water to the upper channel of the Alamo River, which flows north toward the Salton Sea in the valley center, offering suitable opportunities for developing auxiliary distribution structures. By September 1904, nearly 8,000 valley settlers were operating 700 miles of canals and irrigating 75,000 acres.
The Alamo Canal, however, was difficult to operate without upstream control of the Colorado River. The channel required almost constant dredging to control silt, and an extensive levee system was constructed for protection from flood damage. In spite of these precautions, the Colorado River, while carrying a major flood from the Gila River Basin, washed out the Alamo Canal heading in 1905. The river partially changed its course to follow the canal and the Alamo River into the Salton Sea. Water flowed into the interior for nearly 2 years and inundated some 330,000 acres. The Southern Pacific Railroad Company, alarmed about the threat to the prospering Imperial Valley and to the railroad through the basin, finally returned the Colorado River to its natural channel on February 10, 1907, and controlled diversion of irrigation water through the Alamo Canal was resumed.
Although the feasibility of constructing a canal wholly within the United States was studied as early as 1876, a report in 1919 covered the first complete survey and cost estimate for an "All-American" canal. Congress, desiring additional information, authorized an examination which resulted in a report which recommended control of the Colorado River by a multiple-purpose reservoir project at or near Boulder Canyon, and the construction of a high-line canal, together with a diversion dam and desilting works, to carry diverted water into the Imperial Valley.
The All-American Canal System was authorized under the Boulder Canyon Project Act of December 21, 1928 (45 Stat. 1057).
Construction of the All-American Canal began in 1934, following the construction of Hoover Dam. The first irrigation water was delivered in 1940. The construction of Imperial Dam and Desilting Works began in January 1936 and was completed in July 1938. Coachella Canal was built during the period from August 11, 1938, to June 1948. Construction was interrupted by World War II, and work stopped from 1942 to 1944. Construction of the Coachella distribution system was initiated in 1948 and completed in 1954.
The Brock (Drop 2) Storage Reservoir project was recently constructed near Drop 2 on the All-American Canal. Completed in 2010, the new 8,000 acre-foot reservoir stores Colorado River water that has been released from Parker Dam to meet downstream water orders but cannot be delivered for various reasons, such as changed weather conditions, high runoff into the river, or a number of other factors. This water typically is not put to beneficial use within the United States due to the lack of sufficient storage capacity below Parker Dam.
With an assured water supply, growers in the Imperial and Coachella Valleys were able to greatly increase their production. The soils of these two valleys, combined with a favorable climate, were noted for production of winter fruits and vegetables. In the Coachella Valley, farmers specialize in niche crops, such as dates and early-season production of table grapes, melons, citrus and numerous other crops. The nation`s domestic date gardens are concentrated primarily in the Coachella Valley, with 90 percent of this country`s production originating there. The Imperial Irrigation District, served by the All-American Canal, is today the largest irrigation district in the nation, delivering up to 3.1 million acre-feet of Colorado River water to about 500,000 acres of land annually.
Imperial Dam forms a small reservoir area with a nearly stable water surface elevation. Camping, hunting, picnicking, swimming, boating, and year-round fishing for bass, catfish, bluegill, and crappie are popular activities in the reservoir area above the dam.
For specific information about any of these recreation sites, click on the name below.
Imperial Reservoir Area: Mittry Lake Wildlife AreaImperial Reservoir Area: Picacho State Recreation AreaImperial National Wildlife RefugeSquaw Lake CampgroundSenator Wash Day Use Area and Boat Ramp