There are a couple of reasons this particular site was chosen for the dam. First, this is a narrow part of the Columbia River. Second, the bedrock the dam sits on is granite. Granite makes a very good base for a dam as it is very sturdy and doesn’t break apart easily.
Also, we copied what Mother Nature did in the past. During the last Ice Age (13,000+ years ago) the Cordilleran Ice Sheet blocked the Columbia River at the spot where the dam sits today. The ice formed a huge dam about 500 feet taller than Grand Coulee Dam. This forced the Columbia River to flow out of its channel and to flow south which created a new canyon. Large floods, known as the Missoula Floods, also came down this new channel cutting a huge canyon which is now known as the Grand Coulee. This canyon was perfect for storing water to be used to irrigate the Columbia Basin in central Washington. Today Grand Coulee Dam pumps water into this canyon and is used to irrigate approximately 670,000 acres which produce over 80 different crops.
O’Sullivan Dam is named after James O’Sullivan. He belonged to the “Dam College”, which included William (Billy) Clapp and Rufus Woods, who were adamant about bringing water to this dry area of central Washington.
In 1925, Congress directed the Army Corps of Engineers to study all major river systems in the U.S. for the purpose of navigation, power, flood control, and irrigation. Major J.S. Butler was assigned the task of studying the Columbia River. It was Butler’s report that favored the plan to place a high dam that would include irrigation at the Grand Coulee site.
There were 77 men killed during the construction of the dam from 1933 to 1941. An additional four men were killed during the construction of the Nathaniel Washington Power Plant and Forebay Dam from 1967 to 1975.
No one is buried in the dam. The dam was constructed in “blocks” that measured 50 feet wide by 50 feet long by five feet high. The forms were not deep enough to not notice someone trapped in them.
The original part of the dam was constructed in two phases. In the first phase from 1933-1936 unskilled workers received $0.60 per hour. Skilled workers received $0.80 per hour to $1.50 per hour, depending on what their job entailed. They worked an average of 36 hours per week. From 1937-1941 wages were negotiated with the American Federation of Labor (AFL). Under the AFL contract unskilled workers received $0.75 per hour and skilled workers received up to $1.65 per hour.
In order to pour all the concrete necessary for the dam, a system of trestles, cranes, and railroad cars were built. Beginning with the concrete batching plant located on site, large buckets (four cubic yards) were loaded and placed on railroad cars. These cars would then be moved along trestles to the site of the pour. At that point, a crane would pick up the bucket and deliver it to the awaiting 50-foot by 50-foot by 5-foot deep forms.
The exact number of people who had to be relocated because of the dam is unknown. Most who lived upstream of the dam site along the Columbia River had to be relocated because of the huge reservoir (Lake Roosevelt) that was formed. Many of these displaced people upstream were living on the Colville Reservation. In addition 11 towns located along the river were affected, nine of which were relocated: Keller, Lincoln, Gifford, Daisy, Kettle Falls, Marcus, Boyds, Inchelium (which was on the Colville Reservation), and Rice. Two other towns, Peach and Jerome, were not relocated. During the construction of the Third Power Plant and the addition of the Forebay Dam, approximately 200 homes in the Town of Coulee Dam were bought by the federal government and moved or demolished.
Those seemingly little holes are actually 8.5 feet in diameter – you could fit a standard size truck in one of them. They are used to discharge water through the dam when the elevation of the water in the lake is lower than the drum gates at the top of the spillway.
The dam is a very stable structure. It contains over 12 million cubic yards of concrete and is 550 feet thick at its base. The dam is held in place by the weight of its concrete.
It is very unlikely the dam would unexpectedly break. Monitoring occurs on an ongoing basis with instrumentation placed inside the dam and by workers who visually inspect the dam. The more likely scenario is to have too much water upstream of the dam that comes downstream rapidly, such as a flood. If the dam could not hold back an excessive amount of water, the water would come over the top of the dam and potentially flood areas downstream, including cities. In 1948, Vanport City, Oregon, located adjacent to Portland, was destroyed when Grand Coulee Dam couldn't hold back flooding from spring runoff, but the dam was not damaged.
There are three ways to get water from the reservoir behind the dam to the river below the dam. The preferred way is to send it through the turbines in the generators to produce electricity. Spilling water, which does not produce electricity and therefore not desirable, occurs in two ways. One way is spilling through the drum gates located at the top of the dam and which are lowered to release water. These 11 drum gates are 135 feet long and 30 feet high. The other way to release water is through the outlet tubes located across the face of the spillway. There are 40 outlet tubes with a diameter of 8.5 feet each. Operators at the dam control the amount of water that pass through the generators or is spilled.
Grand Coulee Dam provides water to irrigate about 670,000 acres. The Columbia Basin Project was originally planned to have the capacity to irrigate 1.1 million acres, however the project has not yet been completed.
The simple answer is no, the dam is not entirely paid off. The facility was built from 1933-1980. This included the original dam structure and Left Powerhouse completed in 1941, the Right Powerhouse in 1948, the John W. Keys III Pumping Plant in 1951, and the Nathaniel Washington Power Plant in 1980.
There is a 50-year repayment schedule for each section of facility that was built. The original dam, Left Powerhouse, Right Powerhouse, and Pumping Plant have sources of reimbursement: power and irrigation. The irrigators are still paying on their portion. The Columbia Basin Project was developed in blocks. As these blocks were completed, irrigators began their repayments. The first irrigation block was paid off in 2008 and the last is scheduled for 2044.
The Nathaniel Washington Power Plant and Forebay Dam, being the latest addition to the facility, are slightly over 30 years old and so repayments are continuing. Also with the aging of the facility there are continued repairs, replacements, and refurbishments. These additional costs are in the process of being reimbursed.
Grand Coulee Dam had two significant construction periods. The first was from 1933-1941 when the main dam and Left Powerhouse were constructed. The original cost of the dam in 1940s dollars was $300 million. Between 1967 and 1975 a major addition included the Nathaniel Washington Power Plant and Forebay Dam. The cost for this addition was $700 million in 1980s dollars. The equivalent dollar value if these structures were built today would be:
- Grand Coulee Dam (original structure): $5,541,000,000
- Third Power Plant and Forebay Dam: $2,002,000,000
Grand Coulee Dam is the largest hydropower producer in the United States, generating more than 21 billion kilowatt-hours of electricity each year. That’s enough power to supply about 2 million households with electricity for one year.
The top of Grand Coulee Dam is closed to public access, both vehicular and pedestrian.
The laser light show is held nightly at Grand Coulee Dam starting the Saturday of Memorial Day Weekend through September 30. The show lasts about 30 minutes and is free of charge. The laser light show will begin at 10:00 p.m. through July 31. Beginning Aug. 1, the laser light show will start at 9:30 p.m. and it will run at 8:30 p.m. starting Sept. 1. Start times are subject to change.
In short, Grand Coulee Dam stopped the natural migratory runs of fish on the upper Columbia River. This included the second most important salmon fishery on the Columbia River at Kettle Falls, located about 100 miles upstream from the dam. To mitigate for the loss of fish to the upper Columbia, Grand Coulee Dam built, and continues to fund, three fish hatcheries (Leavenworth, Winthrop, and Entiat) downstream of the dam.
The longer answer is that salmon populations on the Columbia River have been in decline since the beginning of the 1800s and continued through the 1900s due to several factors including irrigation projects, small hydroelectric dams on tributaries to the Columbia, over-fishing by the commercial interests (including the increase in the use of fish wheels), increased sport fishing, gaffing of fish on the spawning grounds, and increased domestic and industrial pollution.
Today, Grand Coulee Dam is operated to provide increased flows downstream to assist with juvenile fish passage in the spring and summer. In the winter, water is released from Lake Roosevelt to provide minimum flows to protect redds (fish nests).
In 1938, the Washington State Department of Fisheries and the Bureau of Reclamation studied the issue of preserving salmon and steelhead at Grand Coulee Dam. The publication “Report of the Preliminary Investigations into the Possible Methods of Preserving the Columbia River Salmon and Steelhead at the Grand Coulee Dam” concluded that a fish ladder would not work at Grand Coulee. The fish would have to climb over 300 feet to have passage over the dam. Nothing on that scale had ever been tried. Instead the Washington State Department of Fisheries recommended that hatcheries be built in the mid-Columbia to produce fish. As a result Grand Coulee Dam funds three fish hatcheries at Leavenworth, Winthrop, and Entiat. These hatcheries produce over two million fish which are released into the Columbia.
In the meantime, Chief Joseph Dam was built 50 miles downstream of Grand Coulee Dam. Chief Joseph was not built with a fish passage. Therefore in order for fish to reach the upper Columbia, Chief Joseph would need to address fish passage as well as Grand Coulee. Challenges in building a fish ladder at Grand Coulee include: a long fish ladder (estimated to be over 0.75 miles long) and land needing to be acquired (the ladder would have to go through two small towns). The biggest unknown is if fish would migrate upstream once they entered Lake Roosevelt (the 150 mile long reservoir behind Grand Coulee Dam). Lake Roosevelt is relatively slack compared to the swift moving Columbia River. It is uncertain if the fish would find their way upstream without the swift moving current of the river.
There is also concern that if the fish were to spawn in the mainstem of the Columbia, their redds would be dry in the spring when Lake Roosevelt is drawn down to make room for the spring runoff. Keeping the lake higher for fish in the spring could compromise flood control downstream in a very wet year, if Lake Roosevelt did not have enough room to store the excess water.
At Reclamation, we are stewards of some of the Pacific Northwest’s most economically and environmentally important publicly-owned resources, the centerpiece of which is Grand Coulee Dam. When it comes to fish passage and reintroduction above Grand Coulee, the main question for Reclamation is whether it is possible to realize this idea in an environmentally and economically sound manner.
With little scientific analysis addressing feasibility of fish passage and reintroduction, Reclamation recognizes the need for targeted and credible research to support such a determination. In 2016 we took the first step towards developing this science. In cost-share with the Bonneville Power Administration, Reclamation is funding the Spokane Tribe to assess aquatic habitat conditions above Grand Coulee Dam. This study focuses on quantifying the aquatic habitat in the Upper Columbia River basin, and developing a high-level understanding of the water quality and quantity in these habitats. When the study is complete, we'll evaluate it with regional partners and stakeholders and decide what to do next.
Three fish hatcheries (Leavenworth, Entiat, and Winthrop), were authorized by Congress as mitigation for the construction of Grand Coulee Dam. These hatcheries produce over two million fish per year for release into the upper Columbia River system. Congress also directed that one-quarter of the entire reservoir be set aside for the paramount use of the members of the Confederated Tribes of the Colville Reservation and Spokane Tribe of Indians for fishing, boating, and hunting purposes. The tribes fish the waters below the salmon hatcheries and are allowed to take up to 50% of the fish raised by these hatcheries.
The tribes also work on habitat restoration in the tributaries below Chief Joseph Dam. These tributaries provide excellent spawning grounds to indigenous migrating fish. In addition, a new hatchery has been built just below Chief Joseph Dam that is operated by the Colville Tribes.
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Grand Coulee Visitor Center