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"base_parameter":"Stor", "tsid":"DAWT2.Stor.Inst.0.Top of Flood", "latest_value":199227, "units":"ac-ft", "units_long_name":"Acre-feet" }, { "slug":"stor.top of inactive", "label":"Top of Inactive", "parameter":"Stor", "base_parameter":"Stor", "tsid":"DAWT2.Stor.Inst.0.Top of Inactive", "latest_value":0, "units":"ac-ft", "units_long_name":"Acre-feet" } ], "id":550033, "associatedStructuresCount":0, "conditionAssessDate":null, "conditionAssessDetail":null, "conditionAssessId":6, "damHeight":82, "damLength":7570, "distance":null, "drainageArea":320, "eapId":1, "dsacAssignedDate":"2018-05-14T12:00:00.000Z", "eapMeetsGuidelinesId":1, "emergencyContactsUpdated":"2024-09-10T12:00:00.000Z", "eapLastRevDate":"2021-08-16T12:00:00.000Z", "enforcementAuthorityId":0, "federalId":"TX00009", "oldFederalId":"TX00009", "hazardId":4, "hydraulicHeight":77, "inspectionAuthorityId":0, "inspectionDate":"2022-05-25T12:00:00.000Z", "inspectionFrequency":5, "jurisdictionAuthorityId":0, "latitude":31.9539557840001, "lengthOfLocks":0, "secondaryLengthOfLocks":null, "longitude":-96.6951701359999, "maxDischarge":217797, "maxStorage":323879, "nidHeight":87, "nidStorage":323879, "normalStorage":63300, "numberOfLocks":0, "operationalStatusDate":"2018-05-14T12:00:00.000Z", "operationalStatusId":1, "originalDesignerName":null, "otherStructureId":null, "permittingAuthorityId":0, "politicalPartyId":null, "privateDamId":null, "projectDescription":"The U.S. Army Corps of Engineers (USACE) completed construction of Navarro Mills Dam in May 1963 in accordance with the Flood Control Act approved 3 September 1954 (PL 780, 83rd Congress, 2nd Session), and as modified by the provisions of the Flood Control Act approved 3 July 1958 (PL 85-500, 85th Congress, 2nd Session) and in Advice of Allotment C-126, 6 October 1958. It is located approximately 16 miles southwest of the City of Corsicana in Navarro County, Texas. The dam reduces the risk of downstream flooding along Richland Creek, a tributary of the Trinity River, by holding back waters during heavy rain events. The dam is an earthen embankment, approximately 1.4 miles long, with a gated concrete spillway on the eastern end. The gated spillway is controlled by six tainter gates that hold water to 14 feet below the top of the dam to regulate water storage and releases. The gated spillway also contains two low-flow gated conduits, or openings through the dam, for releasing water in a regulated manner during and after flood events. Additional benefits of the dam are water supply, fish and wildlife management, and recreation.", "riskCharSummary":"Although Navarro Mills Dam reduces the risk of flooding to downstream communities, the dam does not eliminate the risk of flooding. Navarro Mills Dam was designed to reduce the peak flooding levels downstream without risking the structural integrity of the dam. The U.S. Army Corps of Engineers (USACE) completed a risk assessment in April 2017 and classified the risks associated with the project as very low. This classification is based on an extremely unlikely flood event which could cause several equally unlikely scenarios including overtopping at a low spot in the embankment, water to seep through the dam and eventually weaken the dam, and inoperability of the spillway gates leading to overtopping of the gates. In the remote event of a dam breach, the largest impacts would be to the City of Purdon, TX, located approximately 9 miles downstream of the dam. In any of these unlikely scenarios, downstream flooding in Purdon, TX would occur within 3 hours of breach and could be as deep as a two-story structure, destroying buildings and critical infrastructure. In addition, some evacuation routes would be under water, increasing evacuation distances. The most likely scenario that could result in downstream flooding is high volume releases from Navarro Mills Dam through the gated spillway during high water events. These surcharge operational releases occur when the reservoir's flood storage capacity is exceeded and the spillway gates are opened to allow excess water to flow through the spillway. Surcharge releases through the spillway during the largest expected flood in the watershed would put thousands of people at risk and flood waters could be as deep as a one-story building. Although the large downstream communities have well-practiced emergency action plans, and local emergency managers are aware of the unlikely potential for dam failure, breach of the dam would result in significant loss of life and severe economic damages.", "riskManagementMeasures":"In order to lower the risks associated with the dam, inspections and monitoring are performed regularly to ensure the health and safety of the dam. Surveillance and inspections are increased as the lake elevation rises. Routine maintenance and dam safety monitoring are performed to ensure the dam is functioning as designed. New instruments were installed in the embankment above the left abutment of the concrete gated spillway in 2014 to monitor the amount of water seeping through the dam. The downstream left and right abutments of the gated concrete spillway was repaired in 2018 and 2021, respectively, after a shallow embankment slide caused damage to the riprap and embankment. The repairs include reconstructing the slope, replacing the riprap and bedding material, and constructing a new drainage swale. Additionally, Navarro Mills Dam is well maintained with an instrumentation and monitoring system to allow USACE staff to evaluate the dam for changing conditions. The Emergency Action Plan is updated and exercised annually, improving emergency response and coordination between USACE elements and downstream federal, state, county, city agencies, and stakeholders. USACE also communicates risks associated with Navarro Mills Dam annually with stakeholders and Emergency Managers.", "riverName":"RICHLAND CREEK", "separateStructuresCount":0, "sourceAgency":"US Army Corps of Engineers", "spillwayTypeId":1, "spillwayWidth":240, "stateFedId":"TX00009", "stateRegulatoryAgency":null, "stateRegulatedId":0, "structuralHeight":87, "submitDate":"2023-02-24T00:00:00.000Z", "surfaceArea":5070, "volume":2315000, "widthOfLocks":0, "secondaryWidthOfLocks":null, "yearCompleted":1963, "congDist":"Congressional District 06, Texas", "city":"RICHLAND", "county":"Navarro", "aiannh":null, "websiteUrl":"https://www.swf-wc.usace.army.mil/navarro/", "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":"CESWF", "otherNames":null, "ownerNames":"USACE - Fort Worth District", "ownerTypeIds":"3", "primaryDamTypeId":8, "primaryOwnerTypeId":3, "primaryPurposeId":9, "purposeIds":"9;4;5;8", "dsacId":5, "femaRegion":"6", "lastEapExcerDate":"2024-03-26T12:00:00.000Z", "dataUpdated":"2025-04-15T12:00:00.000Z", "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, "thirtyYearAverage":67.4796, "tenthPercentile":57.8075, "ninetiethPercentile":86.1054 }, "id":412048, "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/412048?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/412048?f=jsonld" }, { "rel":"alternate", "type":"text/html", "title":"This document as HTML", "href":"https://api.wwdh.internetofwater.app/collections/usace-edr/items/412048?f=html" }, { "rel":"collection", "type":"application/json", "title":"USACE Access2Water API", "href":"https://api.wwdh.internetofwater.app/collections/usace-edr" } ] }