{ "bbox":null, "type":"Feature", "geometry":{ "bbox":null, "type":"Point", "coordinates":[ -91.64491, 39.52595 ] }, "properties":{ "provider":"MVS", "code":"Mark Twain Lk", "slug":"mark%20twain%20lk", "elevation":null, "horizontal_datum":"", "vertical_datum":"", "state":"MO", "kind":"PROJECT", "nearest_city":"Hannibal", "public_name":"Mark Twain Lake Project", "location_code":412018, "nsid":null, "aliases":{ "NIDID":"MO82201" }, "timeseries":[ { "tsid":"Mark Twain Lk-Salt.Stage.Inst.30Minutes.0.29", "label":"Stage", "base_parameter":"Stage", "parameter":"Stage", "unit":"ft", "unit_long_name":"Feet", "latest_time":"2026-08-25T22:00:00Z", "latest_value":603.93, "delta24h":null, "sort_order":4, "results":null }, { "tsid":"Mark Twain Lk-Salt.Stor.Inst.30Minutes.0.RatingCOE", "label":"Conservation Storage", "base_parameter":"Stor", "parameter":"Stor", "unit":"ac-ft", "unit_long_name":"Acre-feet", "latest_time":"2026-08-25T22:00:00Z", "latest_value":485036.83, "delta24h":null, "sort_order":13, "results":null }, { "tsid":"Mark Twain Lk-Salt.Flow-In.Ave.~1Day.1Day.lakerep-rev", "label":"Inflow", "base_parameter":"Flow", "parameter":"Flow-In", "unit":"cfs", "unit_long_name":"Cubic feet per second", "latest_time":"2026-08-24T05:00:00Z", "latest_value":80.0, "delta24h":null, "sort_order":6, "results":null }, { "tsid":"Mark Twain Lk-Salt.Stage.Inst.30Minutes.0.29", "label":"Stage Tailwater", "base_parameter":"Stage", "parameter":"Stage", "unit":"ft", "unit_long_name":"Feet", "latest_time":"2026-08-25T22:00:00Z", "latest_value":603.93, "delta24h":null, "sort_order":5, "results":null }, { "tsid":"Mark Twain Lk-Salt.Flow-Out.Ave.~1Day.1Day.lakerep-rev", "label":"Outflow", "base_parameter":"Flow", "parameter":"Flow-Out", "unit":"cfs", "unit_long_name":"Cubic feet per second", "latest_time":"2026-08-25T05:00:00Z", "latest_value":400.0, "delta24h":null, "sort_order":7, "results":null }, { "tsid":"Mark Twain Lk-Salt.Stor.Inst.30Minutes.0.RatingCOE", "label":"Flood 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"units_long_name":"Feet", "type":"CONSTANT" }, { "slug":"elev.bottom of power", "label":"Bottom of Power", "parameter":"Elev", "base_parameter":"Elev", "tsid":"Mark Twain Lk.Elev.Inst.0.Bottom of Power", "latest_value":590, "units":"ft", "units_long_name":"Feet", "type":"CONSTANT" }, { "slug":"elev.critical lake level", "label":"Critical Lake Level", "parameter":"Elev", "base_parameter":"Elev", "tsid":"Mark Twain Lk.Elev.Inst.0.Critical Lake Level", "latest_value":615, "units":"ft", "units_long_name":"Feet", "type":"CONSTANT" }, { "slug":"elev.record elevation", "label":"Record Elevation", "parameter":"Elev", "base_parameter":"Elev", "tsid":"Mark Twain Lk.Elev.Inst.0.Record Elevation", "latest_value":640.36, "units":"ft", "units_long_name":"Feet", "type":"CONSTANT" }, { "slug":"elev.seasonal rule curve", "label":"Seasonal Rule Curve", "parameter":"Elev", "base_parameter":"Elev", "tsid":"Mark Twain Lk.Elev.Inst.0.Seasonal Rule Curve", "latest_value":606, "units":"ft", "units_long_name":"Feet", "type":"REGULAR" }, { "slug":"elev.seasonal rule curve production", "label":"Seasonal Rule Curve Production", "parameter":"Elev", "base_parameter":"Elev", "tsid":"Mark Twain Lk.Elev.Inst.0.Seasonal Rule Curve Production", "latest_value":606, "units":"ft", "units_long_name":"Feet", "type":"REGULAR" }, { "slug":"elev.spillway crest", "label":"Spillway Crest", "parameter":"Elev", "base_parameter":"Elev", "tsid":"Mark Twain Lk.Elev.Inst.0.Spillway Crest", "latest_value":600, "units":"ft", "units_long_name":"Feet", "type":"CONSTANT" }, { "slug":"elev.streambed", "label":"Streambed", "parameter":"Elev", "base_parameter":"Elev", "tsid":"Mark Twain Lk.Elev.Inst.0.Streambed", "latest_value":515, "units":"ft", "units_long_name":"Feet", "type":"CONSTANT" }, { "slug":"elev.top of conservation", "label":"Top of Conservation", "parameter":"Elev", "base_parameter":"Elev", "tsid":"Mark Twain Lk.Elev.Inst.0.Top of Conservation", "latest_value":606, "units":"ft", "units_long_name":"Feet", "type":"CONSTANT" }, { "slug":"elev.top of dam", "label":"Top of Dam", "parameter":"Elev", "base_parameter":"Elev", "tsid":"Mark Twain Lk.Elev.Inst.0.Top of Dam", "latest_value":653, "units":"ft", "units_long_name":"Feet", "type":"CONSTANT" }, { "slug":"elev.top of flood", "label":"Top of Flood", "parameter":"Elev", "base_parameter":"Elev", "tsid":"Mark Twain Lk.Elev.Inst.0.Top of Flood", "latest_value":638, "units":"ft", "units_long_name":"Feet", "type":"CONSTANT" }, { "slug":"elev.top of inactive", "label":"Top of Inactive", "parameter":"Elev", "base_parameter":"Elev", "tsid":"Mark Twain Lk.Elev.Inst.0.Top of Inactive", "latest_value":567.2, "units":"ft", "units_long_name":"Feet", "type":"CONSTANT" }, { "slug":"elev.top of induced surcharge", "label":"Top of Induced Surcharge", "parameter":"Elev", "base_parameter":"Elev", "tsid":"Mark Twain Lk.Elev.Inst.0.Top of Induced Surcharge", "latest_value":642, "units":"ft", "units_long_name":"Feet", "type":"CONSTANT" }, { "slug":"elev.top of surcharge", "label":"Top of Surcharge", "parameter":"Elev", "base_parameter":"Elev", "tsid":"Mark Twain Lk.Elev.Inst.0.Top of Surcharge", "latest_value":648, "units":"ft", "units_long_name":"Feet", "type":"CONSTANT" }, { "slug":"stage.fill", "label":"Fill", "parameter":"Stage", "base_parameter":"Stage", "tsid":"Mark Twain Lk.Stage.Inst.0.Fill", "latest_value":0, "units":"ft", "units_long_name":"Feet", "type":"CONSTANT" }, { "slug":"stage.flood", "label":"Flood", "parameter":"Stage", "base_parameter":"Stage", "tsid":"Mark Twain Lk.Stage.Inst.0.Flood", "latest_value":909, "units":"ft", "units_long_name":"Feet", "type":"CONSTANT" }, { "slug":"stage.record stage", "label":"Record Stage", "parameter":"Stage", "base_parameter":"Stage", "tsid":"Mark Twain Lk.Stage.Inst.0.Record Stage", "latest_value":640.36, "units":"ft", "units_long_name":"Feet", "type":"CONSTANT" }, { "slug":"stor.bottom of conservation", "label":"Bottom of Conservation", "parameter":"Stor", "base_parameter":"Stor", "tsid":"Mark Twain Lk.Stor.Inst.0.Bottom of Conservation", "latest_value":90012, "units":"ac-ft", "units_long_name":"Acre-feet", "type":"CONSTANT" }, { "slug":"stor.bottom of flood", "label":"Bottom of Flood", "parameter":"Stor", "base_parameter":"Stor", "tsid":"Mark Twain Lk.Stor.Inst.0.Bottom of Flood", "latest_value":520661, "units":"ac-ft", "units_long_name":"Acre-feet", "type":"CONSTANT" }, { "slug":"stor.streambed", "label":"Streambed", "parameter":"Stor", "base_parameter":"Stor", "tsid":"Mark Twain Lk.Stor.Inst.0.Streambed", "latest_value":0, "units":"ac-ft", "units_long_name":"Acre-feet", "type":"CONSTANT" }, { "slug":"stor.top of conservation", "label":"Top of Conservation", "parameter":"Stor", "base_parameter":"Stor", "tsid":"Mark Twain Lk.Stor.Inst.0.Top of Conservation", "latest_value":520661, "units":"ac-ft", "units_long_name":"Acre-feet", "type":"CONSTANT" }, { "slug":"stor.top of dam", "label":"Top of Dam", "parameter":"Stor", "base_parameter":"Stor", "tsid":"Mark Twain Lk.Stor.Inst.0.Top of Dam", "latest_value":1997476, "units":"ac-ft", "units_long_name":"Acre-feet", "type":"CONSTANT" }, { "slug":"stor.top of flood", "label":"Top of Flood", "parameter":"Stor", "base_parameter":"Stor", "tsid":"Mark Twain Lk.Stor.Inst.0.Top of Flood", "latest_value":1371201, "units":"ac-ft", "units_long_name":"Acre-feet", "type":"CONSTANT" }, { "slug":"stor.top of inactive", "label":"Top of Inactive", "parameter":"Stor", "base_parameter":"Stor", "tsid":"Mark Twain Lk.Stor.Inst.0.Top of Inactive", "latest_value":90012, "units":"ac-ft", "units_long_name":"Acre-feet", "type":"CONSTANT" }, { "slug":"stor.top of induced surcharge", "label":"Top of Induced Surcharge", "parameter":"Stor", "base_parameter":"Stor", "tsid":"Mark Twain Lk.Stor.Inst.0.Top of Induced Surcharge", "latest_value":1526980, "units":"ac-ft", "units_long_name":"Acre-feet", "type":"CONSTANT" }, { "slug":"stor.top of surcharge", "label":"Top of Surcharge", "parameter":"Stor", "base_parameter":"Stor", "tsid":"Mark Twain Lk.Stor.Inst.0.Top of Surcharge", "latest_value":1772396, "units":"ac-ft", "units_long_name":"Acre-feet", "type":"CONSTANT" } ], "id":550148, "associatedStructuresCount":1, "conditionAssessDate":null, "conditionAssessDetail":null, "conditionAssessId":6, "damHeight":138, "damLength":1940, "distance":20, "drainageArea":2318, "eapId":1, "dsacAssignedDate":"2018-10-22T12:00:00.000Z", "eapMeetsGuidelinesId":1, "emergencyContactsUpdated":"2024-07-08T12:00:00.000Z", "eapLastRevDate":"2021-09-08T12:00:00.000Z", "enforcementAuthorityId":0, "federalId":"MO82201", "oldFederalId":"MO82201", "hazardId":4, "hydraulicHeight":133, "inspectionAuthorityId":0, "inspectionDate":"2020-08-18T12:00:00.000Z", "inspectionFrequency":5, "jurisdictionAuthorityId":0, "latitude":39.52441307, "lengthOfLocks":0, "secondaryLengthOfLocks":null, "longitude":-91.643850146, "maxDischarge":276500, "maxStorage":1862000, "nidHeight":188, "nidStorage":1862000, "normalStorage":520661, "numberOfLocks":0, "operationalStatusDate":"2018-10-22T12:00:00.000Z", "operationalStatusId":1, "originalDesignerName":null, "otherStructureId":null, "permittingAuthorityId":0, "politicalPartyId":null, "privateDamId":null, "projectDescription":"The U.S. Army Corps of Engineers (USACE) operates and maintains more than 700 dams across the United States. Mark Twain Lake consist of three project features the main dam named Clarence Cannon Dam, the saddle dam, and the Re-regulation Dam. Clarence Cannon Dam is a high hazard dam located in the Upper Mississippi River Basin at mile 63.0 on the Salt River. It lies in eastern Monroe County and western Ralls County, 20 miles southwest of Hannibal, Missouri and 100 miles northwest of St. Louis, Missouri and consist of a concrete spillway section with a hydro-electric power plant and an earthen embankment section. The Saddle Dam, which consist of earthen embankment, raises a low section in the reservoir\u2019s rim to the same height as the main dam is also considered a high hazard dam. The Re-regulation dam which is considered a run-of-the-river structure, which consist of concrete spillway and earthen embankments, is a significant hazard dam located nine miles downstream. The project was authorized by the Flood Control Act of 23 October 1962 and the name was changed in Section 221 of the Flood Control Act of 27 October 1965 from Joanna Reservoir to Clarence Cannon Dam and Mark Twain Lake. The project\u2019s authorized purposes include: power generation, flood control, recreation, water supply, water quality enhancement, fish and wildlife conservation, and incidental navigation. Construction occurred from 1970 to 1983 and initial filling of the pool began in August of 1983 and minimum pool elevation was achieved in January 1984.", "riskCharSummary":"USACE completed a risk assessment for Clarence Cannon Dam, the Saddle Dam, and the Re-regulation dam in 2018. Clarence Cannon Dam is currently categorized as a Dam Safety Action Classification (DSAC) 4 which is considered low urgency in that there is low incremental risk. The Saddle Dam and the Re-regulation Dam are currently categorized as a DSAC 5 which is considered low risk and is the overall lowest risk rating. Although the projects have historically performed well and the evaluated the risk as relatively low, not all risk is eliminated. Even when the dam operates as intended, downstream flooding could still occur if a very large rainfall event were to require unusually large quantities of water to be released through the dam gates. In the extreme conditions, such as extreme rainfall and earthquakes, the project may experience conditions that it was not designed for, and increased inspections and performance monitoring will occur. Failure is defined as the sudden and uncontrolled release of water. The three probable failures all require an exceptionally rare rainfall events in the first which the Main Dam is overtopping that for a duration that leads to breach and in the other two the pool is at the top of the dam. For the other two failures, pool is loaded up to the crest for an extended duration that through seepage progresses to breach or a concrete monolith slides allowing the pool to breach. The Saddle Dam primary and only failure was due to overtopping and erosion that allows breach of the embankment. The Re-regulation Dam is designed with limited storage during normal and low water operations to ensure adequate flows to support navigation. During high flow events, the dam functions as a run-of-the-river project, allowing the river to pass through naturally. Therefore, in the unlikely event of a dam failure with low or normal water flows in the river, water would not overflow the riverbanks. If the dam failed during a large flood the dam itself would not affect the extent of flooding since it was not storing water. Although these scenarios are considered extremely unlikely, Clarence Cannon Dam has an emergency action plan to reduce the risk of life loss if any of these scenarios were to occur.", "riskManagementMeasures":"USACE manages dam-related flood risks by continually monitoring the condition and health of the dam, prioritizing activities that will most impact the risks, and engaging upstream and downstream emergency managers and members of the public to raise awareness of the dam and support actions to prepare and be ready to respond in the case of a dam-related emergency. USACE works closely with local emergency managers to share what is known about the dam and support the development of local emergency and evacuation plans. USACE regularly updates the emergency action plan for the dam which include inundation maps that have been released to the public via NID. \nIn addition to emergency preparedness routine instrumentation, inspections, and risk assessments are conducted and increased surveillance occurs when hazards exceed pre-established thresholds to ensure the structures are performing as designed. Regular maintenance and repairs are performed as needed to keep the dam functioning properly. Subject matter experts are monitoring the weather, expected precipitation, regional conditions, and pool conditions to anticipate impacts, make projections, and advise on deviations in order to further reduce the risk of an extreme loading event.", "riverName":"SALT RIVER", "separateStructuresCount":1, "sourceAgency":"US Army Corps of Engineers", "spillwayTypeId":1, "spillwayWidth":230, "stateFedId":"MO82201", "stateRegulatoryAgency":null, "stateRegulatedId":0, "structuralHeight":188, "submitDate":"2023-08-04T15:28:16.866Z", "surfaceArea":5900, "volume":3450000, "widthOfLocks":0, "secondaryWidthOfLocks":null, "yearCompleted":1983, "congDist":"Congressional District 06, Missouri", "city":"NEW LONDON", "county":"Ralls", "aiannh":null, "websiteUrl":"https://www.usace.army.mil/Missions/Civil-Works/Dam-Safety-Program/Article/2870967/dam-safety-program/", "coreTypeIds":"3", "damTypeIds":"11;8;9", "fedConstructionIds":"1", "fedDesignIds":"1", "fedFundingIds":"1", "fedInspectionIds":"1", "fedOperationIds":"1", "fedOtherIds":"1", "fedOwnerIds":"1", "fedRegulatoryIds":"1", "formerNames":null, "foundationTypeIds":"1;3", "nonFederalDamOnFederalId":0, "designerNames":"CEMVS", "otherNames":"Mark Twain Lake", "ownerNames":"USACE - St. Louis District", "ownerTypeIds":"3", "primaryDamTypeId":11, "primaryOwnerTypeId":3, "primaryPurposeId":9, "purposeIds":"9;3;4;5;6;8", "dsacId":4, "femaRegion":"7", "lastEapExcerDate":"2024-09-26T12:00:00.000Z", "dataUpdated":"2025-02-04T12:00:00.000Z", "usaceDistrict":"St. Louis District", "noConsequencesId":0, "secretaryAgricultureBuiltId":null, "nrcsWatershedAuthorizationId":null, "isAssociatedStructureId":"No", "fedRegulatedId":"Yes", "inundationNidAddedId":1, "damStatusId":2, "huc06":"071100", "doi_region":null, "doi_region_name":"Mississippi Basin", "doi_region_number":4, "thirtyYearAverage":614.414, "tenthPercentile":536.7284, "ninetiethPercentile":673.9787 }, "id":412018, "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/412018?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/412018?f=jsonld" }, { "rel":"alternate", "type":"text/html", "title":"This document as HTML", "href":"https://api.wwdh.internetofwater.app/collections/usace-edr/items/412018?f=html" }, { "rel":"collection", "type":"application/json", "title":"USACE Access2Water API", "href":"https://api.wwdh.internetofwater.app/collections/usace-edr" } ] }