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"associatedStructuresCount":0, "conditionAssessDate":null, "conditionAssessDetail":null, "conditionAssessId":6, "damHeight":130, "damLength":32328, "distance":null, "drainageArea":1660, "eapId":1, "dsacAssignedDate":"2014-10-29T12:00:00.000Z", "eapMeetsGuidelinesId":1, "emergencyContactsUpdated":"2024-10-02T12:00:00.000Z", "eapLastRevDate":"2021-09-24T12:00:00.000Z", "enforcementAuthorityId":0, "federalId":"TX00008", "oldFederalId":"TX00008", "hazardId":4, "hydraulicHeight":118, "inspectionAuthorityId":0, "inspectionDate":"2024-02-28T12:00:00.000Z", "inspectionFrequency":5, "jurisdictionAuthorityId":0, "latitude":33.0693152740001, "lengthOfLocks":0, "secondaryLengthOfLocks":null, "longitude":-96.964539465, "maxDischarge":216800, "maxStorage":1804300, "nidHeight":135, "nidStorage":1804300, "normalStorage":618400, "numberOfLocks":0, "operationalStatusDate":"2014-10-29T12:00:00.000Z", "operationalStatusId":3, "originalDesignerName":null, "otherStructureId":null, "permittingAuthorityId":0, "politicalPartyId":null, "privateDamId":null, "projectDescription":"Lewisville Dam, which was built by the U.S. Army Corps of Engineers (USACE) in 1955, provides numerous benefits for the surrounding area. The dam was designed to reduce the risk of downstream flooding to the communities of Lewisville, Carrollton, Irving, and Dallas. Since it went into operation, the dam has reduced damage caused by downstream flooding by more than an estimated $54.5 billion (adjusted to 2020 dollars). In 1991, hydropower was added as a project purpose and was installed by the City of Denton to supplement the regional power distribution network. In addition, Lewisville reservoir is a principal municipal water source for the city of Dallas and offers a wide range of outdoor recreational opportunities. The main components of the dam are an earthen embankment, which serves as the main water barrier composed of compacted earth; lifting gates that are operated to control water releases at the dam; a concrete ungated spillway that allows water to flow out when water levels within the reservoir exceed the available flood storage; and a powerhouse that can provide enough electricity to power 2,400 homes. Lewisville Dam is over six miles long and 125 feet tall and is made up of impervious (watertight) clays and shale. The top of the ungated spillway is about three stories lower than the highest part of the dam and when the reservoir water level exceeds the dedicated flood storage levels, the ungated spillway can pass up to 1.6 million gallons of water per second which is enough water to flood a football field almost four feet deep every second. 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, and negative impacts to the environment. Sometimes water must be released to protect the dam\u2019s integrity even though streams and rivers may have already reached or exceeded their capacity.", "riskCharSummary":"Although Lewisville Dam reduces the risk of flooding to downstream communities, the dam does not eliminate the risk of flooding. The most likely scenario that could result in downstream flooding due to floodwaters passed through Lewisville Dam are high volume releases from the dam during high water events. These surcharge operational releases occur when the reservoir's flood storage capacity is exceeded causing flooding in areas adjacent to the reservoir and excess water flows through the spillway and/or outlet works. Lewisville Dam is designed to reduce the peak flooding levels downstream without risking the structural integrity of the dam. Generally, the Elm Fork Trinity River's large floods are long-duration type lasting weeks or even months; however, it is possible that large peak and volume floods could occur in about two weeks duration. Despite the flood reduction benefits the dam provides, very rare, severe storms could still produce high surcharge releases with the potential to exceed the capacity of the downstream levees and impact the communities of Lewisville, Coppell, Carrollton, Farmers Branch, Irving, and Dallas.\n\nIn October 2014, the U.S. Army Corps of Engineers (USACE) completed a risk assessment to evaluate the potential hazards to the dam, expected performance, and associated consequences. The risk assessment classified the risks associated with the Lewisville Dam as high. The classification is based on an extremely unlikely flood event, unlike anything ever experienced by the project, that could lead to a dam breach or large flows over the spillway and potentially to instability of the structure, eventually breaching the dam. In either scenario, downstream flood waters would be deep and move swiftly through the cities located along the Trinity River in Denton and Dallas Counties, including downtown Dallas. This flooding due to dam breach could overflow levees and cause catastrophic damage to buildings and critical infrastructure. Flooded river depths immediately downstream of the dam could exceed the height of a four-story building. Additionally, there would be flood impacts experienced along the Trinity River all the way to the Gulf of America. Although large downstream communities have thorough, well- practiced emergency action plans; local emergency managers who are aware of the unlikely potential for dam failure; local emergency managers who meet regularly with USACE to discuss emergency response to flood events; and a community that is aware of the remote potential for flooding, if a breach of the dam were to occur thousands of people\u2019s lives would be at risk within the inundated area. The USACE is currently constructing dam modifications to reduce the likelihood of breach associated with the risk driving factors identified during the risk assessment.", "riskManagementMeasures":"The U.S. Army Corps of Engineers (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 and update of local evacuation plans to maximize evacuation time and designated evacuation routes; regularly updating the Lewisville Dam Emergency Action Plan; and conducting emergency exercises with state and local response teams. In addition, USACE continues to identify and implement interim risk reduction measures such as clearing vegetation from the sides of the dam, conducting regular surveillance of the dam, and automating instrumentation to track the performance of the dam. USACE conducts detailed inspections of the dam during both normal lake levels and increased surveillance during flood events to ensure the integrity of the structure. Instrumentation and monitoring systems allow USACE staff to monitor the dam for changing conditions that may not be seen at the surface. The frequency of these dam inspections increases when the lake level rises. Regular maintenance and repairs are performed as needed to keep the dam functioning properly.\n\nRisk Management of Lewisville Dam is also a priority for USACE at the national level which has led to the design and current construction of dam safety modifications to address deficiencies identified for Lewisville Dam. While the probability of failure is remote, the risk to human life and property should failure occur is high enough to warrant remediation of the identified deficiencies. The actions being taken to address the deficiencies include constructing a downstream inverted filter berm and seepage collection trenches at two locations, anchoring the spillway weir and constructing an upstream cutoff, overlay the apron on the downstream side of the spillway, and construct a barrier wall downstream of the spillway. In addition, further measures are being taken to reduce risk by adding a filter around the outlet conduit to reduce the possibility of erosion, constructing an upstream berm to address slope stability issues, and partnering with the City of Lewisville to relocate waterlines that previously encroached on the embankment to reduce risk of embankment erosion from a waterline rupture. Additional information on the dam safety modification to Lewisville Dam is available on the USACE Fort Worth District website at the following web address: https://www.swf.usace.army.mil/Home/Lewisville-Lake-Dam/", "riverName":"ELM FORK OF THE TRINITY RIVER", "separateStructuresCount":0, "sourceAgency":"US Army Corps of Engineers", "spillwayTypeId":3, "spillwayWidth":560, "stateFedId":"TX00008", "stateRegulatoryAgency":null, "stateRegulatedId":0, "structuralHeight":135, "submitDate":"2023-02-24T00:00:00.000Z", "surfaceArea":23280, "volume":14422000, "widthOfLocks":0, "secondaryWidthOfLocks":null, "yearCompleted":1955, "congDist":"Congressional District 26, Texas", "city":"LEWISVILLE", "county":"Denton", "aiannh":null, "websiteUrl":"https://www.swf-wc.usace.army.mil/lewisville/", "coreTypeIds":"3", "damTypeIds":"8", "fedConstructionIds":"1", "fedDesignIds":"1", "fedFundingIds":"1", "fedInspectionIds":"1;13", "fedOperationIds":"1", "fedOtherIds":"1", "fedOwnerIds":"1", "fedRegulatoryIds":"1;13", "formerNames":"Garza Little Elm Dam", "foundationTypeIds":"3", "nonFederalDamOnFederalId":0, "designerNames":"CESWF", "otherNames":null, "ownerNames":"USACE - Fort Worth District", "ownerTypeIds":"3", "primaryDamTypeId":8, "primaryOwnerTypeId":3, "primaryPurposeId":9, "purposeIds":"9;4;5;6;8", "dsacId":2, "femaRegion":"6", "lastEapExcerDate":"2025-07-15T12:00:00.000Z", "dataUpdated":"2025-07-16T12:00:00.000Z", "usaceDistrict":"Fort Worth District", "noConsequencesId":0, "secretaryAgricultureBuiltId":null, "nrcsWatershedAuthorizationId":null, "isAssociatedStructureId":"No", "fedRegulatedId":"Yes", "inundationNidAddedId":1, "damStatusId":2, "huc06":"120301", "doi_region":"ART", "doi_region_name":"Arkansas-Rio Grande-Texas Gulf", "doi_region_number":6 }, "id":424048, "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/424048?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/424048?f=jsonld" }, { "rel":"alternate", "type":"text/html", "title":"This document as HTML", "href":"https://api.wwdh.internetofwater.app/collections/usace-edr/items/424048?f=html" }, { "rel":"collection", "type":"application/json", "title":"USACE Access2Water API", "href":"https://api.wwdh.internetofwater.app/collections/usace-edr" } ] }