| Optima Lake | |
| Location: | Texas County, Oklahoma |
| Coords: | 36.6617°N -101.1367°W |
| Type: | Reservoir |
| Basin Countries: | United States |
| Cities: | Hardesty, Oklahoma |
| Pushpin Map: | Oklahoma#USA |
| Pushpin Map Alt: | Location of Optima Lake in Oklahoma, USA. |
Optima Lake was built to be a reservoir in Texas County, Oklahoma. The site is just north of Hardesty and east of Guymon in the Oklahoma Panhandle.[1]
The earthen Optima Lake Dam (National ID # OK20510) was completed in by the United States Army Corps of Engineers, with a height of 120feet, and a length at its crest of 16875feet.[2] Although designed to contain a maximum of 618500acre-feet of water, the lake never reached more than five percent of capacity,[3] and remains effectively empty. Rapid declines in streamflow related to large-scale pumping from the high plains aquifer system, also known as the Ogallala Aquifer, coincided with the completion of the dam,[3] to make the reservoir a dramatic example of unanticipated environmental impacts.
The Corps' website states in part (emphasis in original):
The lake surroundings offer few to no amenities since lake camping facilities and buildings were dismantled for public safety by the Corps in 2010.
The project was originally included as part of the Flood Control Act of 1936, as modified by the Flood Control Act of 1950,[4] [5] but planning and political wrangling delayed the start of construction until 1966.[6] The intent was for the reservoir to fill primarily from the flow of the Beaver River,[7] also known as the North Canadian River.[4] Normal flow on the Beaver River, from 1937 to 1966, averaged 32.2 cubic feet per second.[7] The river had occasional floods, including an October 1923 flood amounting to 109000acre-feet of water, and a September 1941 flood in which the Beaver's flow increased to 44200cuft/s.[4] The river's most recent flow of significance was in October 1965 at 17800cuft/s.[4] In the end the project was authorized for flood control, drinking and irrigation water in the relatively dry Oklahoma panhandle, recreation, and fish and wildlife conservation.[4]
The Guymon Chamber of Commerce, which enthusiastically backed the project, published a pamphlet that touted its expected virtues. The brochure forecast that the lake would be 100feet deep, and its arms would flood up to 10miles up Beaver River and 9miles along its tributary, Coldwater Creek. During the 12 years of construction by the U.S. Army Corps of Engineers, the flow of the Beaver dropped.[7] It was later recognized that because the source of the Beaver was the underground Ogallala Aquifer, being the water table underlying far western Oklahoma and parts of seven other Western states, and due to increased takings from the aquifer for irrigation and drinking water, the river's flow was being reduced to a trickle.[7]
The $46.1-million project was completed in 1978. The dam was constructed of compacted earth fill embankment with gated outlet works and a 1500foot long uncontrolled saddle spillway.[4] The top of the dam is at 2821feet of elevation above sea level.[4] The specifications put the top of the maximum pool at 2814.2feet, the top of the flood control pool at 2779feet, the top of the conservation pool at 2763.5feet, and the top of the inactive pool at 2726feet.[4] The conservation pool was designed to hold 117500acre-feet of water, with 76200acre-feet designated to be available as a water supply.[4] The flood pool capacity was designed for 229500acre-feet, while absolute maximum capacity of the lake was set at 618500acre feet.[4] The Corps forecasted in 1979 that, "The optimum visitation for the project is 600,000 annual visitors and will be reached in 2014."
But water flow in the Beaver, 1977–1987, averaged only 7cuft/s, far less than the 32.2cuft/s historical average.[7] In the mid-1980s, the Corps recognized that the reduced flow of the Beaver was permanent and that the reservoir was not going to fill: the maximum lake level was achieved May 31, 1980 at an elevation of 2722.9feet, whereas the very bottom of the conservation pool was intended to be 2726feet.[4] Subsequently, the flow in the Beaver dropped even further. In the last five year period (from 1989–1993) that the U.S. Geological Survey could measure its flow near Guymon, the river averaged less than 0.2cuft/s.[8]
The Corps formally closed the park in 1995, although the site remained open to the public.[4] With funding from the American Recovery and Reinvestment Act of 2009, about 161 decaying structures including picnic enclosures, campsites, restrooms, dump stations, and numerous power poles, were demolished by September 2010 for safety reasons.[4] As of 2014, the project was receiving 2000 to 5000 visitors annually.
A spending controversy erupted in 2009, when the Corps wanted to use $1.2 million of economic stimulus money to replace rotting guardrails on each side of the paved road across the top of the Optima Dam used by approximately 15 cars a day.[9] Public criticism caused the Corps to instead gate and padlock the road at a cost of $1000.[9] The Corps' September 2010 Section 216 Initial Appraisal Report on Optima Lake indicated the Corps was spending approximately $160,000 per year for annual inspections of dam structures, detailed inspections at five year intervals, and repairs as budgets allowed.[4] That same report indicated that existing dam structures (gate tower, stilling basin, uncontrolled spillway and outlet works) remained in operational condition.[4]
In the 1973 Environmental Impact Statement done by the Corps during the planning process, a "dry lake" option for the project was considered which would have provided for no water retention during normal periods, but would have created an area available as a flood containment pool in the event of abnormally large water events in the area.[10] That concept for Optima was rejected in favor of an active water-containment reservoir; however, the project as it currently exists is consistent with the dry lake option.[11] The Beaver does occasionally still carry off surface flooding after heavy rains, as in April 2016 when the river was flowing near Guymon for the first time in decades following two days of intense rains that caused Texas County to be declared a disaster area,[12] and again in June 2024 when the Guymon area received 7.61 inches of rain in one night which left the Beaver River with fast-moving water.[13]
The overall project included the Optima National Wildlife Refuge, run by the US Fish and Wildlife Service, being initially 2605acres along Coldwater Creek—which has its confluence with the Beaver 0.2miles upstream from the dam—[4] and the Optima Wildlife Management Area, public hunting lands managed by the Oklahoma Department of Wildlife Conservation, initially 2141acres along the Beaver.[4] However, the decreased size of the lake itself has led to Optima National Wildlife Refuge being increased to 4334acres, and the area managed by Oklahoma, including licensed Corps lands above and below the dam, increasing to 8062acres.[4]
Given Optima’s shortcomings, the Corps did an Appraisal Report in 1991 to explore modifying the project, recommending that a reconnaissance level study be conducted to evaluate possible alternatives. But, funding for the follow-up study was not provided.[14] An Initial Appraisal Report was done in 2010, also recommending a reconnaissance level study.[14] Ideas floated in that document included (but were not limited to) piping Guymon sewage plant-treated water to Optima (about 17 miles), transferring lands to other agencies, reselling the lands to the original landowners, or deauthorizing the project and demolishing all structures.[4] However, it was not until 2021 that funding was provided for a Disposition Study.[14] As presented at an October 5, 2022 public meeting, the Disposition Study considered multiple alternatives, including (but not limited to): (a) No Action (the continuation of existing operations), (b) retaining just the dam structure as a dry flood control reservoir, (c) transferring operations to another federal or state agency to maintain a flood control project, or (d) deauthorizing the entire project and disposing of all real property.[14] The study was subsequently put on pause, but is expected to ramp back up in 2024.