{ "bbox":null, "type":"Feature", "geometry":{ "bbox":null, "type":"Point", "coordinates":[ -120.14667, 37.29333 ] }, "properties":{ "provider":"SPK", "code":"Mariposa", "slug":"mariposa", "elevation":458.99, "horizontal_datum":"WGS84", "vertical_datum":"NGVD29", "state":"CA", "kind":"PROJECT", "nearest_city":"Le Grand, CA", "public_name":"Mariposa Reservoir", "location_code":3981827044, "nsid":null, "aliases":{ "NIDID":"CA10107" }, "timeseries":[ { "tsid":"Mariposa-Pool.Stor.Inst.1Hour.0.Calc-val", "label":"Conservation Storage", "base_parameter":"Stor", "parameter":"Stor", "unit":"ac-ft", "unit_long_name":"Acre-feet", "latest_time":"2026-04-14T22:00:00Z", "latest_value":206.0, "delta24h":null, "sort_order":13, "results":null }, { "tsid":"Mariposa.Flow-Res Out.Ave.1Hour.1Hour.Calc-val", "label":"Outflow", "base_parameter":"Flow", "parameter":"Flow-Res Out", "unit":"cfs", "unit_long_name":"Cubic feet per second", "latest_time":"2026-04-14T23:00:00Z", "latest_value":26.13, 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"base_parameter":"Elev", "tsid":"Mariposa.Elev.Inst.0.Top of Flood", "latest_value":439.5, "units":"ft", "units_long_name":"Feet" }, { "slug":"elev.top of gross pool", "label":"Top of Gross Pool", "parameter":"Elev", "base_parameter":"Elev", "tsid":"Mariposa.Elev.Inst.0.Top of Gross Pool", "latest_value":439.5, "units":"ft", "units_long_name":"Feet" }, { "slug":"elev.top of surcharge", "label":"Top of Surcharge", "parameter":"Elev", "base_parameter":"Elev", "tsid":"Mariposa.Elev.Inst.0.Top of Surcharge", "latest_value":450.5, "units":"ft", "units_long_name":"Feet" }, { "slug":"stor.bottom of flood", "label":"Bottom of Flood", "parameter":"Stor", "base_parameter":"Stor", "tsid":"Mariposa.Stor.Inst.0.Bottom of Flood", "latest_value":0, "units":"ac-ft", "units_long_name":"Acre-feet" }, { "slug":"stor.streambed", "label":"Streambed", "parameter":"Stor", "base_parameter":"Stor", "tsid":"Mariposa.Stor.Inst.0.Streambed", "latest_value":0, "units":"ac-ft", "units_long_name":"Acre-feet" }, { "slug":"stor.top of dam", "label":"Top of Dam", "parameter":"Stor", "base_parameter":"Stor", "tsid":"Mariposa.Stor.Inst.0.Top of Dam", "latest_value":25203, "units":"ac-ft", "units_long_name":"Acre-feet" }, { "slug":"stor.top of flood", "label":"Top of Flood", "parameter":"Stor", "base_parameter":"Stor", "tsid":"Mariposa.Stor.Inst.0.Top of Flood", "latest_value":15100, "units":"ac-ft", "units_long_name":"Acre-feet" }, { "slug":"stor.top of gross pool", "label":"Top of Gross Pool", "parameter":"Stor", "base_parameter":"Stor", "tsid":"Mariposa.Stor.Inst.0.Top of Gross Pool", "latest_value":15100, "units":"ac-ft", "units_long_name":"Acre-feet" }, { "slug":"stor.top of surcharge", "label":"Top of Surcharge", "parameter":"Stor", "base_parameter":"Stor", "tsid":"Mariposa.Stor.Inst.0.Top of Surcharge", "latest_value":21600, "units":"ac-ft", "units_long_name":"Acre-feet" } ], "id":549817, "associatedStructuresCount":0, "conditionAssessDate":null, "conditionAssessDetail":null, "conditionAssessId":6, "damHeight":null, "damLength":1330, "distance":8, "drainageArea":107, "eapId":1, "dsacAssignedDate":"2021-06-23T12:00:00.000Z", "eapMeetsGuidelinesId":1, "emergencyContactsUpdated":"2025-05-06T12:00:00.000Z", "eapLastRevDate":"2025-05-06T12:00:00.000Z", "enforcementAuthorityId":0, "federalId":"CA10107", "oldFederalId":"CA10107", "hazardId":4, "hydraulicHeight":83, "inspectionAuthorityId":0, "inspectionDate":"2023-03-22T12:00:00.000Z", "inspectionFrequency":5, "jurisdictionAuthorityId":0, "latitude":37.291179304, "lengthOfLocks":0, "secondaryLengthOfLocks":null, "longitude":-120.1478922859999, "maxDischarge":30000, "maxStorage":21500, "nidHeight":88, "nidStorage":21500, "normalStorage":4300, "numberOfLocks":0, "operationalStatusDate":"2021-06-23T12:00:00.000Z", "operationalStatusId":2, "originalDesignerName":null, "otherStructureId":null, "permittingAuthorityId":0, "politicalPartyId":null, "privateDamId":null, "projectDescription":"The U.S. Army Corps of Engineers (USACE) built and completed Mariposa Dam in 1949. Mariposa Dam is one of four dams that are a part of the Merced County Stream Group Project that was authorized by the Flood Control Act of 1944. Mariposa Dam is located about 18 miles east of Merced, California on Mariposa Creek. The dam structure consists of an earthfill embankment that includes an unlined and ungated spillway located near the eastern end of the dam. In addition, the project consists of two dikes and an ungated outlet works. The Mariposa Dam project was constructed solely for flood risk reduction purposes and is typically a dry dam, only holding back water during large rain events. The dam controls runoff from 107 square miles of foothill and mountain drainage.", "riskCharSummary":"Mariposa Dam has historically performed well and significantly reduces the risk of flooding to downstream communities. However, it does not fully eliminate the potential for downstream flooding. USACE completed a risk assessment for Mariposa Dam in 2019 and classified the risks associated with the project as moderate. USACE identified two primary areas of dam safety concern regarding Mariposa Dam: the lack of spillway adequacy and the potential for water to overtop the dam during an extreme flood event. During an extreme flood event, the high flow of water over the unlined and ungated spillway could cause erosion in the spillway channel, which can potentially undermine the spillway control structure, eventually leading to downstream flooding. Another scenario that could potentially cause significant downstream flooding is if water flows over the top of the dam due to an extremely rare and large flood event. This unlikely event would cause significant property damage and potentially harm people downstream. Potentially impacted infrastructure includes road networks, communication facilities, electric substations, police and fire stations, hospitals, schools, and an airport. Although these scenarios are considered extremely unlikely, there is an emergency action plan for Mariposa Dam to lower the risk of life loss if any of these scenarios occurred.", "riskManagementMeasures":"USACE works closely with local emergency managers, regularly updates the emergency action plan, and conducts emergency exercises with state, federal, and local partners, all of which help reduce risk to the public. USACE performs regular inspections and instrument monitoring to ensure that the structure is performing as designed and could help detect any areas of potential concern. The frequency of these checks increases when Mariposa Lake rises. USACE incorporates weather forecasts to make informed decisions on how to operate the dam. In most scenarios, the downstream communities would have a coordinated warning notification within hours depending on location before water reaches their homes. However, during very large and rare earthquake events, there may be little to no warning.", "riverName":"MARIPOSA CREEK", "separateStructuresCount":0, "sourceAgency":"US Army Corps of Engineers", "spillwayTypeId":3, "spillwayWidth":260, "stateFedId":"CA10107", "stateRegulatoryAgency":null, "stateRegulatedId":0, "structuralHeight":88, "submitDate":"2023-02-16T17:25:42.210Z", "surfaceArea":510, "volume":0, "widthOfLocks":0, "secondaryWidthOfLocks":null, "yearCompleted":1948, "congDist":"Congressional District 05, California", "city":"LE GRAND", "county":"Mariposa", "aiannh":null, "websiteUrl":"https://www.spk.usace.army.mil/Missions/Civil-Works/Dam-Safety-Program/", "coreTypeIds":"3", "damTypeIds":"8", "fedConstructionIds":"1", "fedDesignIds":"1", "fedFundingIds":"1", "fedInspectionIds":"1", "fedOperationIds":"1", "fedOtherIds":"1", "fedOwnerIds":"1", "fedRegulatoryIds":"1", "formerNames":null, "foundationTypeIds":null, "nonFederalDamOnFederalId":0, "designerNames":null, "otherNames":"Mariposa Reservoir", "ownerNames":"USACE - Sacramento District", "ownerTypeIds":"3", "primaryDamTypeId":8, "primaryOwnerTypeId":3, "primaryPurposeId":9, "purposeIds":"9;6", "dsacId":3, "femaRegion":"9", "lastEapExcerDate":"2025-04-09T12:00:00.000Z", "dataUpdated":"2025-07-01T12:00:00.000Z", "usaceDistrict":"Sacramento District", "noConsequencesId":0, "secretaryAgricultureBuiltId":null, "nrcsWatershedAuthorizationId":null, "isAssociatedStructureId":"No", "fedRegulatedId":"Yes", "inundationNidAddedId":1, "damStatusId":2, "huc06":"180400", "doi_region":"CGB", "doi_region_name":"California-Great Basin", "doi_region_number":10 }, "id":3981827044, "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/3981827044?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/3981827044?f=jsonld" }, { "rel":"alternate", "type":"text/html", "title":"This document as HTML", "href":"https://api.wwdh.internetofwater.app/collections/usace-edr/items/3981827044?f=html" }, { "rel":"collection", "type":"application/json", "title":"USACE Access2Water API", "href":"https://api.wwdh.internetofwater.app/collections/usace-edr" } ] }