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Capacity", "parameter":"Stor", "base_parameter":"Stor", "tsid":"GGLT2.Stor.Inst.0.Design Capacity", "latest_value":219964, "units":"ac-ft", "units_long_name":"Acre-feet" }, { "slug":"stor.spillway crest", "label":"Spillway Crest", "parameter":"Stor", "base_parameter":"Stor", "tsid":"GGLT2.Stor.Inst.0.Spillway Crest", "latest_value":130629, "units":"ac-ft", "units_long_name":"Acre-feet" }, { "slug":"stor.streambed", "label":"Streambed", "parameter":"Stor", "base_parameter":"Stor", "tsid":"GGLT2.Stor.Inst.0.Streambed", "latest_value":0, "units":"ac-ft", "units_long_name":"Acre-feet" }, { "slug":"stor.top of conservation", "label":"Top of Conservation", "parameter":"Stor", "base_parameter":"Stor", "tsid":"GGLT2.Stor.Inst.0.Top of Conservation", "latest_value":38068, "units":"ac-ft", "units_long_name":"Acre-feet" }, { "slug":"stor.top of dam", "label":"Top of Dam", "parameter":"Stor", "base_parameter":"Stor", "tsid":"GGLT2.Stor.Inst.0.Top of Dam", "latest_value":130629, "units":"ac-ft", "units_long_name":"Acre-feet" }, { "slug":"stor.top of flood", "label":"Top of Flood", "parameter":"Stor", "base_parameter":"Stor", "tsid":"GGLT2.Stor.Inst.0.Top of Flood", "latest_value":131793, "units":"ac-ft", "units_long_name":"Acre-feet" }, { "slug":"stor.top of inactive", "label":"Top of Inactive", "parameter":"Stor", "base_parameter":"Stor", "tsid":"GGLT2.Stor.Inst.0.Top of Inactive", "latest_value":63, "units":"ac-ft", "units_long_name":"Acre-feet" } ], "id":550030, "associatedStructuresCount":0, "conditionAssessDate":null, "conditionAssessDetail":null, "conditionAssessId":6, "damHeight":162, "damLength":6650, "distance":null, "drainageArea":246, "eapId":1, "dsacAssignedDate":"2016-05-07T12:00:00.000Z", "eapMeetsGuidelinesId":1, "emergencyContactsUpdated":"2024-09-27T12:00:00.000Z", "eapLastRevDate":"2020-09-20T12:00:00.000Z", "enforcementAuthorityId":0, "federalId":"TX08006", "oldFederalId":"TX08006", "hazardId":4, "hydraulicHeight":160, "inspectionAuthorityId":0, "inspectionDate":"2025-04-16T12:00:00.000Z", "inspectionFrequency":5, "jurisdictionAuthorityId":0, "latitude":30.6672695820001, "lengthOfLocks":0, "secondaryLengthOfLocks":null, "longitude":-97.72553489, "maxDischarge":342000, "maxStorage":236500, "nidHeight":162, "nidStorage":236500, "normalStorage":37100, "numberOfLocks":0, "operationalStatusDate":"2016-05-07T12:00:00.000Z", "operationalStatusId":2, "originalDesignerName":null, "otherStructureId":null, "permittingAuthorityId":0, "politicalPartyId":null, "privateDamId":null, "projectDescription":"The U.S. Army Corps of Engineers (USACE) built North San Gabriel Dam on the North Fork of the San Gabriel River in the mid-to-late 70's to reduce the risk of flooding to the downstream city of Georgetown and adjacent towns and counties. Although flood risk management is the project's primary focus, the authorized project purposes include water supply, water quality control, irrigation, recreation and fish and wildlife conservation. These benefits all significantly improve the quality of life in the area. North San Gabriel Dam is located 3.5 miles west of Georgetown, Texas. The dam consists of an earthen embankment that holds water in the reservoir, gates that are operated to control water releases at the dam, and a spillway, which allows water to flow out when water levels within the reservoir become high. The main dam is made up of soil and rock and is 162 feet (just over 16 stories) high near its center at a crest elevation of 861.3 feet (NAVD88 vertical datum control). The embankment is slightly over one mile long starting at about Lake Overlook Road and the Project Office on the north end to the 1000-foot long spillway towards the southwest. Rockfill dikes 40-50 feet high are located along the downstream side of the dam for spillway release embankment erosion protection during uncontrolled spillway releases during rare flooding events. The reservoir is kept at or below the conservation pool elevation of 791.3 feet NAVD88 for most of the year. When heavy rains occur, surface water runoff is stored in the reservoir until the swollen streams and rivers below the dam recede and can handle the release of stored water without damage to lives, property or the environment. Sometimes water must be released to protect the dam's integrity even though these streams and rivers may have already reached or exceeded their capacity.", "riskCharSummary":"Even though North San Gabriel Dam reduces the risk of flooding to the downstream communities, the dam does not eliminate the risk of flooding. The most likely scenario that could result in downstream flooding from North San Gabriel Dam are high volume releases through the uncontrolled overflow spillway during significant storm events. Such higher surcharge releases from the spillway could create conditions similar to how the river might behave if the dam did not exist. Although North San Gabriel Dam has historically performed well and safely passed the 1992 flood event with 2\u2010feet of water through the spillway, extreme rainfall events may result in up to 27\u2010feet of water over the spillway. A spillway event of this magnitude would impact critical infrastructure downstream and has the potential to result in loss of life in Georgetown, Texas, and surrounding downstream communities. USACE Fort Worth District completed a risk assessment for North San Gabriel Dam in May 2016 and classified the risk associated with North San Gabriel Dam as moderate. This risk classification is primarily driven by the very low probability for dam failure and the large population at risk living downstream of the dam. The potential for breach of North San Gabriel Dam was assessed to be related to two primary risks associated with earthen embankment dams: 1) Overtopping of the main dam or closure dikes during an extreme flood event leading to erosion and eventual breach of the dam, or 2) potential for breach of the dam at reservoir levels leading up to the top of the dam due to water passing through the dam embankment and foundation into internal drains or into solution cavities in the limestone foundation. In the remote event of a dam breach the largest impacts would be to the city of Georgetown and adjacent downstream areas. Should such a breach occur, significant flooding greater than 15 feet deep would be experienced down the San Gabriel River to at least Granger Dam located downstream. Although these communities have emergency action plans and local emergency managers meet regularly with USACE to discuss emergency response to flood events, including the unlikely potential for dam failure, breach of the dam would result in significant loss of life and severe economic damages.", "riskManagementMeasures":"USACE Fort Worth District continuously takes additional steps to reduce the risk to the public. This includes working closely with local emergency managers to encourage and support the development of local evacuation plans to maximize evacuation time and designated evacuation routes; regularly updating the North San Gabriel Dam Emergency Action Plan; conducting emergency exercises with state and local response teams; and annually communicating risks associated with North San Gabriel Dam with stakeholders and Emergency Managers. In addition, USACE continues to identify and implement interim risk reduction measures, such as removing and maintaining vegetation growth along the toes of the dam; maintaining road surfaces on the dam to provide some erosion resistance should water flow over the dam; and is planning to stockpile emergency materials on site to lessen the impacts associated with unexpected poor performance or overtopping. USACE Fort Worth District regularly inspects and monitors instruments that help ensure that the structure is performing as intended and to help detect potential concerns. The frequency of dam inspections increases when the lake level rises. Regular maintenance and repairs are performed on project features as needed to keep the dam properly functioning.", "riverName":"NORTH FORK SAN GABRIEL RIVER", "separateStructuresCount":0, "sourceAgency":"US Army Corps of Engineers", "spillwayTypeId":3, "spillwayWidth":1000, "stateFedId":"TX08006", "stateRegulatoryAgency":null, "stateRegulatedId":0, "structuralHeight":162, "submitDate":"2023-10-26T00:00:00.000Z", "surfaceArea":1310, "volume":4653580, "widthOfLocks":0, "secondaryWidthOfLocks":null, "yearCompleted":1980, "congDist":"Congressional District 31, Texas", "city":"GEORGETOWN", "county":"Williamson", "aiannh":null, "websiteUrl":"https://www.usace.army.mil/Missions/Civil-Works/Dam-Safety-Program/Article/2870967/dam-safety-program/", "coreTypeIds":"3", "damTypeIds":"8", "fedConstructionIds":"1", "fedDesignIds":"1", "fedFundingIds":"1", "fedInspectionIds":"1", "fedOperationIds":"1", "fedOtherIds":"1", "fedOwnerIds":"1", "fedRegulatoryIds":"1", "formerNames":"North Fork Dam", "foundationTypeIds":"1;3", "nonFederalDamOnFederalId":0, "designerNames":"CESWF", "otherNames":"Lake Georgetown", "ownerNames":"USACE - Fort Worth District", "ownerTypeIds":"3", "primaryDamTypeId":8, "primaryOwnerTypeId":3, "primaryPurposeId":9, "purposeIds":"9;4;5;8", "dsacId":3, "femaRegion":"6", "lastEapExcerDate":"2025-03-13T12:00:00.000Z", "dataUpdated":"2025-07-09T12:00:00.000Z", "usaceDistrict":"Fort Worth District", "noConsequencesId":0, "secretaryAgricultureBuiltId":null, "nrcsWatershedAuthorizationId":null, "isAssociatedStructureId":"No", "fedRegulatedId":"Yes", "inundationNidAddedId":1, "damStatusId":2, "huc06":"120702", "doi_region":"ART", "doi_region_name":"Arkansas-Rio Grande-Texas Gulf", "doi_region_number":6 }, "id":160048, "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/160048?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/160048?f=jsonld" }, { "rel":"alternate", "type":"text/html", "title":"This document as HTML", "href":"https://api.wwdh.internetofwater.app/collections/usace-edr/items/160048?f=html" }, { "rel":"collection", "type":"application/json", "title":"USACE Access2Water API", "href":"https://api.wwdh.internetofwater.app/collections/usace-edr" } ] }