Lake Thunderbird Water Supply - City of Norman

Lake Thunderbird Water SupplyNorman Project, OklahomaFebruary 2010

Bureau of Reclamation• Reclamation was established in1902 to “reclaim” the arid Westby bringing water and power toundeveloped regions of the U.S.• Our mission is to manage, develop,and protect water and relatedresources in an environmentallyand economically sound manner inthe interest of the American public.• Reclamation has constructed more than 600dams and reservoirs, including major projects such asHoover Dam and Grand Coulee Dam.

Oklahoma-TexasArea Office•Oversight responsibility for 11Reclamation projects inOklahoma, Texas, and Kansas.•This includes Norman Dam andLake Thunderbird.KansasOklahomaTexasOklahoma CityAustin

Norman ProjectBenefits• Municipal andIndustrial WaterSupply• Flood Control• Recreation• Fish and WildlifeEnhancementConservation Storage• 105,927 acre-feetWater Permit• 21,600 acre-ft/yr(M&I)

Norman Project• Reclamation completedconstruction of Norman Damin 1965.• The United States owns theNorman Project whichconsists of:– Norman Dam– Pumping plants andpipelines– 6,080 acre reservoir(Lake Thunderbird)– 7,035 acres of surroundingproject land

Norman Project• The Central Oklahoma MasterConservancy District isresponsible for operation ofthe Dam and Reservoir.• The District provides Projectwater from Lake Thunderbirdto the City of Norman, MidwestCity, and Del City using 2pumping plants and 30 milesof pipeline.• Oklahoma Tourism andRecreation Department isresponsible for managingproject lands and recreationareas.

Lake Thunderbird Watershed

Surface Water Permit for Norman Project• The Oklahoma Water Resources Board issued a surfacewater permit to the District based on the original yieldcalculations for Lake Thunderbird.• Storage quantity required to deliver the Project yield farexceeds the yield itself due to evaporation losses and othervariables.• Water Permit is 21,600 ac-ft/year (~7 billion gallons/year).

Reservoir Yield• Amount of water that can be used each year including the yearsof the most critical drought without emptying the Reservoir.• Calculated using an operational model.• Based on historic inflow and evaporation data.• Water balance on a monthly time step.• Initial Vol. + Total In – Total Out = Final Vol.• Considers future sediment accumulation.PrecipitationEvaporationStream Flow Into ReservoirReservoirSeepageFlood ReleasesD/S ReleaseRequirementsM&I Water PumpedOut of Reservoir

Modeled Reservoir StorageReservoir model assuming full delivery of permitted water.

Norman Project Yield• Norman Project yield is a conjunctive yield which relies on bothreservoir water and supplemental groundwater.• Conjunctive yield increases water availability by supplying 100%of the demand from the Reservoir during wet periods and relyingon groundwater to supplement the Reservoir during the mostsevere droughts.

Norman Project Yield Cont…• Based on this conjunctive yield, when reservoir storage fallsbelow 31,000 ac-ft (i.e., below elevation 1,020 feet), the Districtmust reduce deliveries from the reservoir to prevent the Reservoirfrom going dry.• The Cities must have supplemental groundwater supplies tooffset reduced deliveries from the Reservoir when this occurs.• The lowest reservoir elevation to date was ~1,030 feet duringthe 2006 drought, which did not trigger reduced deliveriesfrom the Reservoir.

Reservoir Augmentation• As the City of Norman has grown, it has become increasinglydependent on groundwater as a primary water source ratherthan a supplemental water supply for the reservoir.• An alternative to the City's supplemental groundwater supplywill be needed to offset reduced water deliveries from thereservoir when storage is less than 31,000 ac-ft.• The District is currently evaluating alternate supplementalwater supplies.