{ "bbox":null, "type":"Feature", "geometry":{ "bbox":null, "type":"Point", "coordinates":[ -101.43246, 47.50498 ] }, "properties":{ "provider":"NWDM", "code":"GARR", "slug":"garr", "elevation":null, "horizontal_datum":"WGS84", "vertical_datum":"NGVD29", "state":"ND", "kind":"PROJECT", "nearest_city":"Mandan", "public_name":"Garrison Dam & Reservoir", "location_code":3161030, "nsid":null, "aliases":{ "NIDID":"ND00145" }, "timeseries":[ { "tsid":"GARR.Flow-Out.Inst.1Hour.0.Raw-A2W", "label":"Outflow", "base_parameter":"Flow", "parameter":"Flow-Out", "unit":"cfs", "unit_long_name":"Cubic feet per second", "latest_time":"2026-04-14T22:00:00Z", "latest_value":16909.1, "delta24h":null, "sort_order":7, "results":null }, { "tsid":"GARR.Conc-DissolvedOxygen.Inst.1Hour.0.Best-MRBWM", "label":"Dissolved Oxygen", "base_parameter":"Conc", "parameter":"Conc-DissolvedOxygen", "unit":"ppm", "unit_long_name":"Parts per million", "latest_time":"2026-04-14T22:00:00Z", "latest_value":15.29, "delta24h":null, "sort_order":18, "results":null }, { "tsid":"GARR-Tailwater.Elev.Inst.1Hour.0.Best-MRBWM", "label":"Elevation Tailwater", "base_parameter":"Elev", "parameter":"Elev", "unit":"ft", "unit_long_name":"Feet", "latest_time":"2026-04-14T22:00:00Z", "latest_value":1667.28, "delta24h":null, "sort_order":3, "results":null }, { "tsid":"GARR.Temp-Air.Inst.1Hour.0.Best-MRBWM", "label":"Air Temperature", "base_parameter":"Temp", "parameter":"Temp-Air", "unit":"F", "unit_long_name":"Fahrenheit", "latest_time":"2026-04-14T22:00:00Z", "latest_value":55.5, "delta24h":null, "sort_order":22, "results":null }, { "tsid":"GARR.Energy.Total.1Hour.0.Best-MRBWM", "label":"Power Generation", "base_parameter":"Energy", "parameter":"Energy", "unit":"MWh", "unit_long_name":"Megawatt-hours", "latest_time":"2026-04-14T22:00:00Z", "latest_value":199.0, "delta24h":null, "sort_order":15, "results":null }, { "tsid":"GARR.Elev.Inst.1Hour.0.Best-MRBWM", "label":"Elevation", "base_parameter":"Elev", 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exclusive flood control", "label":"Top of Exclusive Flood Control", "parameter":"Elev", "base_parameter":"Elev", "tsid":"GARR.Elev.Inst.0.Top of Exclusive Flood Control", "latest_value":1854, "units":"ft", "units_long_name":"Feet" }, { "slug":"elev.top of flood", "label":"Top of Flood", "parameter":"Elev", "base_parameter":"Elev", "tsid":"GARR.Elev.Inst.0.Top of Flood", "latest_value":1854, "units":"ft", "units_long_name":"Feet" }, { "slug":"elev.top of multipurpose", "label":"Top of Multipurpose", "parameter":"Elev", "base_parameter":"Elev", "tsid":"GARR.Elev.Inst.0.Top of Multipurpose", "latest_value":1850, "units":"ft", "units_long_name":"Feet" }, { "slug":"elev.top of sediment", "label":"Top of Sediment", "parameter":"Elev", "base_parameter":"Elev", "tsid":"GARR.Elev.Inst.0.Top of Sediment", "latest_value":1775, "units":"ft", "units_long_name":"Feet" }, { "slug":"elev.top of surcharge", "label":"Top of Surcharge", "parameter":"Elev", "base_parameter":"Elev", "tsid":"GARR.Elev.Inst.0.Top of Surcharge", "latest_value":1858.5, "units":"ft", "units_long_name":"Feet" }, { "slug":"stor.bottom of exclusive flood control", "label":"Bottom of Exclusive Flood Control", "parameter":"Stor", "base_parameter":"Stor", "tsid":"GARR.Stor.Inst.0.Bottom of Exclusive Flood Control", "latest_value":21956000, "units":"ac-ft", "units_long_name":"Acre-feet" }, { "slug":"stor.bottom of multipurpose", "label":"Bottom of Multipurpose", "parameter":"Stor", "base_parameter":"Stor", "tsid":"GARR.Stor.Inst.0.Bottom of Multipurpose", "latest_value":17745000, "units":"ac-ft", "units_long_name":"Acre-feet" }, { "slug":"stor.top of conservation", "label":"Top of Conservation", "parameter":"Stor", "base_parameter":"Stor", "tsid":"GARR.Stor.Inst.0.Top of Conservation", "latest_value":17744640, "units":"ac-ft", "units_long_name":"Acre-feet" }, { "slug":"stor.top of exclusive flood control", "label":"Top of Exclusive Flood Control", "parameter":"Stor", "base_parameter":"Stor", "tsid":"GARR.Stor.Inst.0.Top of Exclusive Flood Control", "latest_value":23451000, "units":"ac-ft", "units_long_name":"Acre-feet" }, { "slug":"stor.top of flood", "label":"Top of Flood", "parameter":"Stor", "base_parameter":"Stor", "tsid":"GARR.Stor.Inst.0.Top of Flood", "latest_value":23451300, "units":"ac-ft", "units_long_name":"Acre-feet" }, { "slug":"stor.top of multipurpose", "label":"Top of Multipurpose", "parameter":"Stor", "base_parameter":"Stor", "tsid":"GARR.Stor.Inst.0.Top of Multipurpose", "latest_value":21956000, "units":"ac-ft", "units_long_name":"Acre-feet" }, { "slug":"stor.top of sediment", "label":"Top of Sediment", "parameter":"Stor", "base_parameter":"Stor", "tsid":"GARR.Stor.Inst.0.Top of Sediment", "latest_value":4794000, "units":"ac-ft", "units_long_name":"Acre-feet" } ], "id":550154, "associatedStructuresCount":2, "conditionAssessDate":null, "conditionAssessDetail":null, "conditionAssessId":6, "damHeight":null, "damLength":11300, "distance":10, "drainageArea":180940, "eapId":1, "dsacAssignedDate":"2022-12-21T12:00:00.000Z", "eapMeetsGuidelinesId":1, "emergencyContactsUpdated":"2023-09-06T12:00:00.000Z", "eapLastRevDate":"2009-09-01T12:00:00.000Z", "enforcementAuthorityId":1, "federalId":"ND00145", "oldFederalId":"ND00145", "hazardId":4, "hydraulicHeight":180, "inspectionAuthorityId":1, "inspectionDate":"2023-06-30T12:00:00.000Z", "inspectionFrequency":5, "jurisdictionAuthorityId":1, "latitude":47.498626464, "lengthOfLocks":0, "secondaryLengthOfLocks":null, "longitude":-101.412813779, "maxDischarge":827000, "maxStorage":26000000, "nidHeight":210, "nidStorage":26000000, "normalStorage":18500000, "numberOfLocks":0, "operationalStatusDate":"2022-12-21T12:00:00.000Z", "operationalStatusId":2, "originalDesignerName":null, "otherStructureId":null, "permittingAuthorityId":1, "politicalPartyId":null, "privateDamId":null, "projectDescription":"Garrison Dam and Reservoir is owned, operated, and maintained by the U.S. Army Corps of Engineers (USACE). Operating since 1955, it is the second-most upstream of six projects built on the mainstem of the upper Missouri River which, in combination with dams on the river\u2019s tributaries, reduce the risk of downstream flooding along the Missouri and Mississippi rivers. When not operating to reduce flood impacts, this \u201cmainstem\u201d system of dams is managed to balance hydropower generation, water supply, water quality, irrigation, fish and wildlife conservation, navigation, and recreation benefits. \n\nThe dam consists of an earthen embankment, an outlet structure for releasing stored water, a powerhouse, and a gated spillway to release excess water during times of extreme runoff from rain and snowmelt. During normal operations, USACE releases up to 41,000 cubic feet of water per second (cfs) (one cubic foot of water is equal to 7.5 gallons) through five powerhouse outlet tunnels to manage reservoir elevations and generate power. As operations shift to reducing flood risks during periods of high runoff, water also is released through three additional outlet tunnels which, combined, can release up to 98,000 cfs. When reservoir levels from extreme storms or snowmelt exceed the outlet structure\u2019s release capacity, additional releases can be made using 28 spillway gates to reduce the likelihood of water flowing over the embankment (overtopping), which can lead to dam failure, or breach. The spillway was designed to additionally release up to 827,000 cfs. This large but controlled, intentional flow is called a \u201cnon-breach\u201d release. \n\nFor perspective, the largest release of water from Garrison Dam as a result of flooding was a total of 150,000 cfs from the powerhouse outlet structure tunnels, and the spillway in 2011. It is important to understand that the dam is designed to release far more water when necessary and these large releases can occur with minimal to no warning, even with warning systems in place.", "riskCharSummary":"Although Garrison Dam continues to reliably reduce floods, it alone cannot eliminate the risk of flooding (nor can the system of dams in which it operates). While unlikely, a non-breach releases when the reservoir is full is critical to reduce the chance of dam overtopping, even if streams and rivers below the dam have reached or exceeded their capacity. Impacts on downstream populations and structures along the Missouri and Mississippi rivers would be overwhelming, but a breach would allow water stored behind the dam to significantly intensify downstream flooding.\n\nWhen USACE last assessed the dam\u2019s ability to meet flood risk management goals, it was determined that the primary threats that could lead to a breach during an extreme flood, with the reservoir at or near its maximum storage level, are damage to the spillway during non-breach releases and erosion of the dam\u2019s foundation from water flowing beneath the embankment. Although these scenarios are very unlikely, failure of the dam or spillway would require historic water releases from the downstream Missouri River dams (Oahe, Big Bend, Fort Randall, and Gavins Point) to preserve their structural integrity. In an extreme case, water from Garrison could exceed the storage capacities of these dams, leading to overtopping and \u201ccascading\u201d dam failures. Over the course of days to weeks, these flows would result in swift, deep, and life-threatening flooding in numerous communities (both with and without levees) along the Missouri and Mississippi rivers. This would substantially impact property, the economy, and critical infrastructure (such as power and water utilities, transportation systems, and commercial and industrial facilities). \n\nUSACE categorized the risk associated with Garrison Dam as \u201chigh\u201d among its more than 700 dams due to the potential loss of life and large, national-scale consequences should an unlikely breach occur. This database and the accompanying inundation maps provide additional details, including consequences for a range of release volumes, non-breach releases, and dam failure. Please note that some scenarios in this database for the six USACE dams on the upper Missouri River do not depict the full extent of downstream inundation including the extent of \u201ccascading\u201d inundation that could develop from upstream Missouri River dam failure(s). For more information on the USACE Dam Safety Program and risk assessments, visit: https://www.usace.army.mil/Missions/Civil-Works/Dam-Safety-Program.", "riskManagementMeasures":"Ongoing Actions: The USACE Dam Safety Program takes proactive steps to reduce risk to life, property, and the environment during both normal operations and extreme floods. Dam experts routinely monitor and observe the dam, conduct regular maintenance and repairs, and work closely with state and local emergency management agencies with responsibilities in communities potentially affected by high flows to improve preparedness, evacuation planning, and public awareness of flood risks. For more information visit: https://www.usace.army.mil/Missions/Civil-Works/Dam-Safety-Program.\n\nActions at Garrison Dam: USACE is currently evaluating opportunities to further reduce risks associated with Garrison Dam. Following flooding in 2011, and the first-ever use of the spillway, multiple foundation drainage systems were upgraded to prevent water from eroding the dam\u2019s foundation and numerous repairs have been made to the spillway to improve its resiliency during future flood events. For more information visit: https://www.nwo.usace.army.mil/Missions/Civil-Works/Planning/Planning-Projects/Garrison-Dam-Safety-Modification-Study.\n\nBuilding Awareness: Since dams do not eliminate flood risk, communities downstream of USACE\u2019s Missouri River dams are encouraged to monitor National Weather Service flood forecasts during periods of heavy rain and snowmelt and learn about potential flood impacts to their family, home, and community. It is important to understand community notification plans, including safe, efficient evacuation routes, and consider preparedness and emergency actions to reduce individual risks. To learn more and get the latest information on water management in the Missouri River basin, visit: https://www.nwd.usace.army.mil/MRWM.", "riverName":"MISSOURI RIVER", "separateStructuresCount":2, "sourceAgency":"US Army Corps of Engineers", "spillwayTypeId":1, "spillwayWidth":1336, "stateFedId":"ND00145", "stateRegulatoryAgency":null, "stateRegulatedId":1, "structuralHeight":210, "submitDate":"2023-02-16T17:25:41.558Z", "surfaceArea":133000, "volume":66500000, "widthOfLocks":0, "secondaryWidthOfLocks":null, "yearCompleted":1953, "congDist":"Congressional District 00, North Dakota", "city":"STANTON", "county":"Mercer", "aiannh":null, "websiteUrl":"https://www.nwo.usace.army.mil/Missions/Dam-and-Lake-Projects/Missouri-River-Dams/Garrison/", "coreTypeIds":"3", "damTypeIds":"8", "fedConstructionIds":"1", "fedDesignIds":"1", "fedFundingIds":"1", "fedInspectionIds":"1", "fedOperationIds":"1", "fedOtherIds":"1", "fedOwnerIds":"1", "fedRegulatoryIds":"1", "formerNames":null, "foundationTypeIds":"1;3", "nonFederalDamOnFederalId":0, "designerNames":"CENWO", "otherNames":"Lake Sakakawea", "ownerNames":"USACE - Omaha District", "ownerTypeIds":"3", "primaryDamTypeId":8, "primaryOwnerTypeId":3, "primaryPurposeId":6, "purposeIds":"6;2;3;5;9", "dsacId":2, "femaRegion":"8", "lastEapExcerDate":"2024-03-12T12:00:00.000Z", "dataUpdated":"2025-07-03T12:00:00.000Z", "usaceDistrict":"Omaha District", "noConsequencesId":0, "secretaryAgricultureBuiltId":null, "nrcsWatershedAuthorizationId":null, "isAssociatedStructureId":"No", "fedRegulatedId":"Yes", "inundationNidAddedId":1, "damStatusId":2, "huc06":"101301", "doi_region":"MB", "doi_region_name":"Missouri Basin", "doi_region_number":5, "thirtyYearAverage":20109.6797, "tenthPercentile":13622.0598, "ninetiethPercentile":24710.0584 }, "id":3161030, "links":[ { "type":"application/json", "rel":"root", "title":"The landing page of this server as JSON", "href":"https://api.wwdh.internetofwater.app?f=json" }, { "type":"text/html", "rel":"root", "title":"The landing page of this server as HTML", "href":"https://api.wwdh.internetofwater.app?f=html" }, { "rel":"self", "type":"application/geo+json", "title":"This document as JSON", "href":"https://api.wwdh.internetofwater.app/collections/usace-edr/items/3161030?f=json" }, { "rel":"alternate", "type":"application/ld+json", "title":"This document as RDF (JSON-LD)", "href":"https://api.wwdh.internetofwater.app/collections/usace-edr/items/3161030?f=jsonld" }, { "rel":"alternate", "type":"text/html", "title":"This document as HTML", "href":"https://api.wwdh.internetofwater.app/collections/usace-edr/items/3161030?f=html" }, { "rel":"collection", "type":"application/json", "title":"USACE Access2Water API", "href":"https://api.wwdh.internetofwater.app/collections/usace-edr" } ] }