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"latest_value":200.0, "delta24h":null, "sort_order":23, "results":null } ], "name":"Saylorville Lake Reservoir", "hasResopsAverages":"false", "nidId":"IA00017", "nidid":"", "levels":[ { "slug":"elev.streambed", "label":"Streambed", "parameter":"Elev-Pool", "base_parameter":"Elev", "tsid":"SAYI4.Elev-Pool.Inst.0.Streambed", "latest_value":800, "units":"ft", "units_long_name":"Feet", "type":"CONSTANT" }, { "slug":"elev.top of conservation", "label":"Top of Conservation", "parameter":"Elev-Pool", "base_parameter":"Elev", "tsid":"SAYI4.Elev-Pool.Inst.0.Top of Conservation", "latest_value":836, "units":"ft", "units_long_name":"Feet", "type":"CONSTANT" }, { "slug":"elev.top of dam", "label":"Top of Dam", "parameter":"Elev-Pool", "base_parameter":"Elev", "tsid":"SAYI4.Elev-Pool.Inst.0.Top of Dam", "latest_value":915.5, "units":"ft", "units_long_name":"Feet", "type":"CONSTANT" }, { "slug":"elev.top of flood", "label":"Top of Flood", "parameter":"Elev-Pool", "base_parameter":"Elev", 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"units":"ac-ft", "units_long_name":"Acre-feet", "type":"CONSTANT" } ], "id":549701, "associatedStructuresCount":0, "conditionAssessDate":null, "conditionAssessDetail":null, "conditionAssessId":6, "damHeight":119, "damLength":6658, "distance":null, "drainageArea":5823, "eapId":1, "dsacAssignedDate":"2015-07-21T12:00:00.000Z", "eapMeetsGuidelinesId":1, "emergencyContactsUpdated":"2025-01-21T12:00:00.000Z", "eapLastRevDate":"2025-01-21T12:00:00.000Z", "enforcementAuthorityId":0, "federalId":"IA00017", "oldFederalId":"IA00017", "hazardId":4, "hydraulicHeight":120, "inspectionAuthorityId":0, "inspectionDate":"2022-12-06T12:00:00.000Z", "inspectionFrequency":1, "jurisdictionAuthorityId":0, "latitude":41.703602, "lengthOfLocks":0, "secondaryLengthOfLocks":null, "longitude":-93.681099, "maxDischarge":213700, "maxStorage":641000, "nidHeight":125, "nidStorage":641000, "normalStorage":74000, "numberOfLocks":0, "operationalStatusDate":"2015-07-21T12:00:00.000Z", "operationalStatusId":1, "originalDesignerName":null, "otherStructureId":null, "permittingAuthorityId":0, "politicalPartyId":null, "privateDamId":null, "projectDescription":"The U.S. Army Corps of Engineers (USACE) completed construction of Saylorville Dam in June 1975 for the purpose of flood risk management, water quality, water supply, recreation, and fish and wildlife. Saylorville Dam is located on the Des Moines River about 9 miles north of the City of Des Moines, Iowa. The earthen dam is over a mile long with a maximum height of 125 feet. Water can be released from the lake in two ways. The first is through the gated outlet structure, which consist of a gate tower, a 22-foot-diameter reinforced concrete channel, and a stilling basin, which helps slow down water as it is released from the lake. The second is through an auxiliary spillway located on the west side of the dam. The spillway structure consists of a concrete barrier wall with a concrete paved chute and side walls. The spillway allows water to flow over the top of the barrier wall during extremely high lake levels. The spillway structure transitions into a natural ground spillway that empties into the Des Moines River approximately a half mile downstream of the dam. The spillway has inflatable gates that when raised can hold back an additional 6 feet of water above the top of the barrier wall. If the reservoir forecast falls within this 6-feet range, the gates are raised and an auxiliary spillway release is prevented. When water levels are expected to be higher than the top of these gates, the gates are lowered, and water passes over the spillway. Saylorville Dam has prevented over $420 million in flood damages and protects more than 50,000 people living and working in the area below the dam. The highest lake elevation observed was in 1993 and was just over 8 feet higher than the crest of the auxiliary spillway. Water has reached the spillway six times, in 1984, 1991, twice in 1993, 2008, and 2010. The 1993 event also released the record amount of water through the dam at 47,000 cubic feet per second, approximately 22% of the design capacity.", "riskCharSummary":"USACE completed a risk assessment in April 2015 and classified the risk associated with Saylorville Dam as low. Water released from the dam could impact densely populated sections of Des Moines with little warning time in the extremely unlikely event of a dam failure. The dam was found to be well-designed, well-constructed, and well-maintained and is expected to be reliable during major floods. However, there is a very remote risk of dam failure from extremely high lake levels eroding areas along the spillway structure or forcing water to seep through the dam around the gated outlet structure. Although highly unlikely, a dam failure would produce a devastating flood with flood depths greater than 15 feet through downtown Des Moines. The flood would inundate a large portion of the City of Des Moines along with several small towns and rural communities along the Des Moines River. Approximately 50,000 people live or work within the worst-case inundation area of the flooding caused by a dam failure.", "riskManagementMeasures":"USACE works to reduce the risks posed to the community by Saylorville Dam. The dam's Emergency Action Plan is updated regularly, and the emergency notification charts are updated annually. This plan has been coordinated with state and local Emergency Management Agencies to help improve their dam incident response planning and preparedness responsibilities. Emergency exercises are routinely held with local and state emergency responders and stakeholders to enhance the local communities' response plan and evacuation procedures. Dam breach flood maps will be available for public viewing on the National Inventory of Dams in late 2021. USACE is developing a detailed communication plan based on the latest risk assessment findings and will engage in communication activities with state and local representatives, stakeholders, emergency managers, and the general public to increase awareness. The dam has a robust instrumentation and monitoring program that allows USACE staff to regularly monitor the dam's performance under changing lake levels. USACE operations and engineering staff routinely conducts detailed inspections of the dam during both normal and high lake levels to ensure the integrity of the dam, identify deficiencies, and monitor known deficiencies. The dam is well maintained through continuous operations and regular maintenance activities. Lastly, the Des Moines River Master Reservoir Regulation Manual, Water Control Manual for Saylorville Lake was updated in coordination with upstream and downstream stakeholders, to allow the lake to be better managed in terms of earlier reservoir releases ahead of increasing lake levels in an effort to prevent auxiliary spillway releases.", "riverName":"DES MOINES RIVER", "separateStructuresCount":0, "sourceAgency":"US Army Corps of Engineers", "spillwayTypeId":1, "spillwayWidth":430, "stateFedId":"IA00017", "stateRegulatoryAgency":null, "stateRegulatedId":0, "structuralHeight":125, "submitDate":"2023-02-16T17:25:16.075Z", "surfaceArea":5520, "volume":8400000, "widthOfLocks":0, "secondaryWidthOfLocks":null, "yearCompleted":1975, "congDist":"Congressional District 03, Iowa", "city":"DES MOINES", "county":"Polk", "aiannh":null, "websiteUrl":"https://www.usace.army.mil/Missions/Civil-Works/Dam-Safety-Program/Article/2870967/dam-safety-program/", "coreTypeIds":"3", "damTypeIds":"9;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":"CEMVR", "otherNames":"Saylorville Lake", "ownerNames":"USACE - Rock Island District", "ownerTypeIds":"3", "primaryDamTypeId":9, "primaryOwnerTypeId":3, "primaryPurposeId":9, "purposeIds":"9;5;8", "dsacId":4, "femaRegion":"7", "lastEapExcerDate":"2024-12-03T12:00:00.000Z", "dataUpdated":"2025-06-05T12:00:00.000Z", "usaceDistrict":"Rock Island District", "noConsequencesId":0, "secretaryAgricultureBuiltId":null, "nrcsWatershedAuthorizationId":null, "isAssociatedStructureId":"No", "fedRegulatedId":"Yes", "inundationNidAddedId":1, "damStatusId":2, "huc06":"071000", "doi_region":null, "doi_region_name":"Mississippi Basin", "doi_region_number":4 }, "id":40017, "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/40017?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/40017?f=jsonld" }, { "rel":"alternate", "type":"text/html", "title":"This document as HTML", "href":"https://api.wwdh.internetofwater.app/collections/usace-edr/items/40017?f=html" }, { "rel":"collection", "type":"application/json", "title":"USACE Access2Water API", "href":"https://api.wwdh.internetofwater.app/collections/usace-edr" } ] }