Beginning in the 1890s, various proposals were made to transfer water from the west slope of the Continental Divide to the East Slope communities along the Front Range of the Colorado Rockies. In 1907, Summit County promoter Colonel James Haven Meyers, "Lord of the Lenawee," proposed a six-mile long Continental Divide bore between Peru Creek and Silver Plume. Meyers and George Bancroft filed papers for the water diversion but the bore was never started.
In 1904, the newly established United States Reclamation Service (USRS) completed a report that suggested raising the elevation of Grand Lake, in northern Summit County, by 20 feet. At the lake's outlet, a dam would create a reservoir storing about 140,000 acre-feet of water. The plan included construction of a 12-mile tunnel from Grand Lake to either the Big Thompson River or St. Vrain Creek.
Eleven years later, Congress passed a bill creating the 260,000-acre Rocky Mountain National Park, 50 miles northwest of Denver. That bill shaped the direction of future trans-mountain water diversion in the area. The measure specifically granted permission for the USRS to "enter upon and utilize for flowage or other purposes any area within said park which may benecessary for the development and maintenance of a Government Reclamation Project." The beginning of the Colorado-Big Thompson (CBT) Project was within site, eventually leading to the Green Mountain Reservoir.
President Roosevelt approved the secretary of the interior's finding of feasibility for the CBT project on December 21, 1937. Congress authorized spending an estimated $44 million for construction in the 1938 Interior Department appropriations bill.
On October 12, 1938, private engineers from around the country, USRS staffers, and other interested parties met in downtown Denver's Customhouse to watch the opening of five bids on construction of the highest and largest earth-fill dam ever built by the Bureau. A little more than a month later in Washington, Secretary of Interior Harold Ickes announced the first contract awarded for the construction of the CBT to the Warner Construction Co. of Chicago on a low bid of $4,226,206.20.
The contract covered the building of the Green Mountain Dam and Power Plant located on the Blue River in northern Summit County, Colorado. Warner had 1,620 days, until May 1943, to complete construction. The design of the earth- and rock-fill dam called for the dam to stand 309 feet high with a crest length of 1,150 feet and hold 4.5 million cubic yards of material. An adjoining reservoir would cover 2,000 acres and hold 152,000 acre-feet of water.
The first official workday was December 1, 1938. Some work actually began two months earlier when Reclamation commenced preliminary clearing of a campsite and stringing of power lines from Dillon to the dam site. Because of the site's remoteness and the severity of high country winters, most construction at Green Mountain Dam was seasonal. Attempting to avoid excessive delays, Reclamation extended the existing road from Kremmling, the nearest railroad point, to the dam and camp.
In that first winter in the mountains, Warner's men completed the camp and moved in equipment. Reclamation's headquarters camp was a thousand feet downstream from the southwest end of the dam. The camp consisted of 25 bunkhouses, commissary, mess hall, warehouse, and field offices. On average, the bunkhouses were 200 chilly feet away from the community bathhouse.
Early in construction, trailers, small shacks, and tents bloomed near the work site. In an attempt to comply with sanitary regulations, Warner built a small town on the left bank of the Blue River, 1,200 feet upstream from the construction area. Warner laid gravel roads and installed water, sewer and streetlight systems. Workers paid $6 per month for a 30' x 40'' space, electricity, water, sewer, and use of the laundry room, and trash collection. A one-room school barracks held 39 to 46 grade school children and five to eight high schoolers.
Labor controversy followed CBT during its first spring and summer of construction. On July 12, 1939, a strike was called by five American Federation of Labor (AFL) craft unions to support demands for collective bargaining recognition and a closed shop. The State Industrial Commission called the shutdown illegal because union officials failed to comply with a Colorado statue requiring 30 days' notice of intention to strike. Reclamation chose to stay on the sidelines as the strike was "a matter for the contractor and workers to settle between themselves."
Summit County swirled with rumors of local unionists phoning Denver's AFL headquarters for 500 reinforcements, and "dozens of cars and trucks carrying an estimated 500 Mexicans, Negroes and hard cases" were on route to the mountains to join the strikers. Warner tried to hire strikebreakers, and at 4:30 p.m. on August 1, an anti-union caravan headed toward the main gate only to find the road littered with structural iron and equipment. Described by a Denver newspaper, the strikebreakers were "Jumping from their cars," driving "the picket force aside by sheer force of numbers." At the end of the day, two picket lines had been broken. The sole injury belonged to one strikebreaker, his scalp cut by a flying rock.
On August 4, Colorado Governor Ralph Carr called out a National Guard force equipped with rifles, machine guns, and two tanks. Carr declared martial law in Grand and Summit counties, as negotiations between all parties continued. On August 22, Warner and the AFL reached agreement, and the union won permission to sign a closed-shop agreement on September 15.
Warner's men drove the diversion tunnel for the Blue River. In May 1940, after the removal of 150,000 cubic yards of material, the tunnel was completed. Work on the dam itself went forward at the same time.
World events intervened in the completion of the CBT. On November 15, 1942, the War Production Board (WPB) suspended all work to conserve steel and other vital war material. On the last day of 1942, construction on all project features came to a halt, except Green Mountain Dam and Power Plant.
By the last week of May 1943, on schedule, the Green Mountain Power Plant generating units began supplying power to war plants in Denver. By November 1943, Green Mountain Dam construction was complete.
The width of the embankment's base is 1,500 feet, eventually narrowing to a 40-ft. wide, 1,150-ft. long crest. The 309-ft. high dam embankment contains about 3.5 million cubic yards of clay, sand, and gravel roller compacted in six-inch layers. The dam's upstream face is made up of 740,000 cubic yards of cobblestones and coarse rock. The primary source of rock came from a borrow pit on the left abutment above the dam site. The capacity of the reservoir is 153,639 acre-feet. When full, the reservoir has a surface area of approximately 2,125 acres.
Green Mountain Dam also contains outlet works, a 1,070-ft. concrete-lined open channel spillway, and a hydroelectric generation plant. The concrete-lined, 18-ft. diameter outlet tunnel terminates at the hoist house and gate chamber. At the gate chamber, two 102-inch ring seal gates control the flow of water through the 102-inch penstocks that lead to the power plant to drive two 13,500 KW Francis turbines. Two 44-inch tube valves that branch off the penstocks control a bypass through the power plant.
The remaining Green Mountain Camp buildings are just north of the dam. Their preservation and interpretation will take money and effort. For now, they are slowly weathering away. Please let SHS know if you are interested in this project.
Directions: The Green Mountain Dam and Reservoir is located approximately twenty miles north of Silverthorne on State Highway 9. Beginning at the point in Silverthorne where interstate I - 70 passes over State Highway 9, proceed north for approximately twenty miles. The town of Heeney, CO is on the reservoir and is about 24 miles north of Silverthorne.