{ "bbox":null, "type":"Feature", "geometry":{ "bbox":null, "type":"Point", "coordinates":[ -71.7472, 43.1886 ] }, "properties":{ "provider":"NAE", "code":"HKD", "slug":"hkd", "elevation":366.01, "horizontal_datum":"WGS84", "vertical_datum":"", "state":"NH", "kind":"PROJECT", "nearest_city":"Concord", "public_name":"Hopkinton Dam", "location_code":8083021, "nsid":null, "aliases":{ "NIDID":"NH00004", "CWMS Legacy Naming":"HKD", "CWMS Standard Naming":"HKD", "USGS Station Number":"01085500" }, "timeseries":[ { "tsid":"HKD.Flow.Inst.15Minutes.0.DCP-rev", "label":"Outflow", "base_parameter":"Flow", "parameter":"Flow", "unit":"cfs", "unit_long_name":"Cubic feet per second", "latest_time":"2026-08-25T22:00:00Z", "latest_value":126.68, "delta24h":null, "sort_order":7, "results":null }, { "tsid":"HKD.Temp-Air.Inst.15Minutes.0.DCP-rev", "label":"Air Temperature", "base_parameter":"Temp", "parameter":"Temp-Air", "unit":"F", "unit_long_name":"Fahrenheit", "latest_time":"2026-08-25T22:00:00Z", "latest_value":88.7, "delta24h":null, "sort_order":22, "results":null }, { "tsid":"HKD.Stor.Inst.15Minutes.0.DCP-rev", "label":"Flood Storage", "base_parameter":"Stor", "parameter":"Stor", "unit":"ac-ft", "unit_long_name":"Acre-feet", "latest_time":"2026-08-25T22:00:00Z", "latest_value":111.63, "delta24h":null, "sort_order":11, "results":null }, { "tsid":"HKD.Elev-Pool.Inst.15Minutes.0.DCP-rev", "label":"Elevation", "base_parameter":"Elev", "parameter":"Elev-Pool", "unit":"ft", "unit_long_name":"Feet", "latest_time":"2026-08-25T22:00:00Z", "latest_value":380.37, "delta24h":null, "sort_order":1, "results":null }, { "tsid":"HKD.Precip.Inst.15Minutes.0.DCP-rev", "label":"Precipitation", "base_parameter":"Precip", "parameter":"Precip", "unit":"in", "unit_long_name":"Inches", "latest_time":"2026-08-25T22:00:00Z", "latest_value":36.85, "delta24h":null, "sort_order":16, "results":null }, { "tsid":"HKD.Flow-Inflow.Total.15Minutes.6Hours.DCP-rev", "label":"Inflow", "base_parameter":"Flow", "parameter":"Flow-Inflow", "unit":"cfs", "unit_long_name":"Cubic feet per second", "latest_time":"2026-08-25T21:00:00Z", "latest_value":129.46, "delta24h":null, "sort_order":6, "results":null }, { "tsid":"HKD.Stage-TAILWATER.Inst.15Minutes.0.DCP-rev", "label":"Stage Tailwater", "base_parameter":"Stage", "parameter":"Stage-TAILWATER", "unit":"ft", "unit_long_name":"Feet", "latest_time":"2026-08-25T22:00:00Z", "latest_value":1.59, "delta24h":null, "sort_order":5, "results":null } ], "name":"Hopkinton Dam", "hasResopsAverages":"true", "nidId":"NH00004", "nidid":"", "levels":[ { "slug":"elev.bottom of normal", "label":"Bottom of Normal", "parameter":"Elev-Pool", "base_parameter":"Elev", "tsid":"HKD.Elev-Pool.Inst.0.Bottom of Normal", "latest_value":366, "units":"ft", "units_long_name":"Feet", "type":"CONSTANT" }, { "slug":"elev.streambed", "label":"Streambed", "parameter":"Elev-Pool", "base_parameter":"Elev", "tsid":"HKD.Elev-Pool.Inst.0.Streambed", "latest_value":366, "units":"ft", 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"label":"Top of Flood", "parameter":"Stor", "base_parameter":"Stor", "tsid":"HKD.Stor.Inst.0.Top of Flood", "latest_value":70100, "units":"ac-ft", "units_long_name":"Acre-feet", "type":"CONSTANT" }, { "slug":"stor.top of normal", "label":"Top of Normal", "parameter":"Stor", "base_parameter":"Stor", "tsid":"HKD.Stor.Inst.0.Top of Normal", "latest_value":1, "units":"ac-ft", "units_long_name":"Acre-feet", "type":"CONSTANT" } ], "id":550190, "associatedStructuresCount":0, "conditionAssessDate":null, "conditionAssessDetail":null, "conditionAssessId":6, "damHeight":71, "damLength":790, "distance":null, "drainageArea":382, "eapId":1, "dsacAssignedDate":"2022-09-09T12:00:00.000Z", "eapMeetsGuidelinesId":1, "emergencyContactsUpdated":"2024-12-20T12:00:00.000Z", "eapLastRevDate":"2020-11-12T12:00:00.000Z", "enforcementAuthorityId":1, "federalId":"NH00004", "oldFederalId":"NH00004", "hazardId":4, "hydraulicHeight":64, "inspectionAuthorityId":1, "inspectionDate":"2021-11-02T12:00:00.000Z", "inspectionFrequency":5, "jurisdictionAuthorityId":1, "latitude":43.1886318410001, "lengthOfLocks":0, "secondaryLengthOfLocks":null, "longitude":-71.747641358, "maxDischarge":59700, "maxStorage":128000, "nidHeight":71, "nidStorage":128000, "normalStorage":700, "numberOfLocks":0, "operationalStatusDate":"2022-09-09T12:00:00.000Z", "operationalStatusId":1, "originalDesignerName":null, "otherStructureId":null, "permittingAuthorityId":1, "politicalPartyId":null, "privateDamId":null, "projectDescription":"The U.S. Army Corps of Engineers (USACE) built Hopkinton Dam from 1959 to 1962 across the Contoocook River. The dam holds back water during flood events and works together with nearby Everett Dam to reduce the risk of downstream flooding on the Merrimack River. Hopkinton Dam normally holds a 14 to 16-foot deep, permanent pool that is produced by a downstream dam whose pool backs up into the Hopkinton Dam reservoir. The dam was built in response to the severe flooding that occurred in the region in 1936. Since it began operations through 2021, the dam reduced damage caused by downstream flooding by more than $241.9 million.\n\nThe dam is made of compacted earth and rock fill and is approximately 7.5 stories (75 feet) high. Three 11-foot by 11-foot rectangular concrete pipes called conduits pass through the dam. Metal gates at the upstream side of the conduits are opened to allow water to pass through the dam and are closed when water needs to be stored during flood events. Two dikes (Dike H-2 and Dike H-3), also composed of earth and rock fill, with approximate heights equivalent to 8 and 7 stories (77 and 66 feet) were constructed to close off low areas around the reservoir. To maintain the structural integrity of the dam when the water level in the reservoir gets high, water can also be released across the spillway, a sloped concrete structure located at the western end of the nearby Dike H-3. A spillway is similar in concept to a sink overflow that prevents a sink bowl from completely overflowing. The spillway is approximately the length of a football field and approximately four and a half stories below the top of the dam and dikes.", "riskCharSummary":"USACE completed a risk assessment of Hopkinton Dam in 2021 and has classified the risks associated with the dam as Low. The dam significantly reduces the risk of flooding to surrounding communities. However, it does not entirely eliminate the risk. The most likely scenario that could result in downstream flooding from Hopkinton Dam would be an uncontrolled high volume release of water from the dam's spillway during significant storm events. The amount of water being released could be great enough to cause flooding in downstream communities. Such higher releases from the spillway could create conditions similar to how the river might behave during a flood event if the dam did not exist. \n\nThere are also extremely unlikely, but far more devastating scenarios that would result in failure of the dam and downstream flooding: water seeping through or below the earth embankment results in voids within the dam as the soil erodes, potentially weakening the dam. Were any of these events to occur, an uncontrolled surge of water would flow out of the reservoir, flooding downstream communities. Contoocook, Concord, and Manchester, NH and Lowell, MA are the major areas in immediate danger in the event of the flood. Towns and cities further downstream would also be impacted, but less so. \nEven though very unlikely, if any of the scenarios described above were to occur, the downstream floodwater would be swift and deep, destroying buildings and key infrastructure, and those caught unaware and/or unable to evacuate could perish. In the less likely dam breach scenarios, the water depth, property damage, and lives lost would likely be far greater than flooding due to spillway discharges. In a worst case scenario, you could see water higher than a three and a half story building.", "riskManagementMeasures":"No emergency situation currently exists at Hopkinton Dam. There is very low risk to the public under normal circumstances. Should a crisis occur, we will use our expertise to quickly find a solution to resume normal operations. While we cannot completely eliminate risk, we will take actions to reduce the risks. We closely monitor the performance of Hopkinton Dam and will modify operations if necessary to lower risk to the public. We will continue to work closely with state and local emergency managers, conducting emergency exercises, and incorporate any new information into our Emergency Action Plan for the dam. We will also continue our rigorous monitoring and surveillance of the dam, especially during high water events. We closely follow rainfall forecasts to determine when high water events may occur so that necessary flood warnings may be issued in a timely manner. USACE is undertaking additional study to further understand the risk associated with Hopkinton Dam, and what, if any, actions can be completed to reduce the risk.", "riverName":"CONTOOCOOK RIVER", "separateStructuresCount":0, "sourceAgency":"US Army Corps of Engineers", "spillwayTypeId":3, "spillwayWidth":300, "stateFedId":"NH00004", "stateRegulatoryAgency":"NH DES", "stateRegulatedId":1, "structuralHeight":71, "submitDate":"2023-02-16T17:25:26.097Z", "surfaceArea":220, "volume":1919000, "widthOfLocks":0, "secondaryWidthOfLocks":null, "yearCompleted":1962, "congDist":"Congressional District 02, New Hampshire", "city":"WEST HOPKINTON", "county":"Merrimack", "aiannh":null, "websiteUrl":"https://www.nae.usace.army.mil/Missions/Civil-Works/Flood-Risk-Management/New-Hampshire/Hop-Ev/", "coreTypeIds":"3", "damTypeIds":"5;8", "fedConstructionIds":"1", "fedDesignIds":"1", "fedFundingIds":"1", "fedInspectionIds":"1", "fedOperationIds":"1", "fedOtherIds":"1", "fedOwnerIds":"1", "fedRegulatoryIds":"1", "formerNames":null, "foundationTypeIds":"3", "nonFederalDamOnFederalId":0, "designerNames":"CENAE", "otherNames":"Hopkinton Lake", "ownerNames":"USACE - New England District", "ownerTypeIds":"3", "primaryDamTypeId":5, "primaryOwnerTypeId":3, "primaryPurposeId":9, "purposeIds":"9;5", "dsacId":4, "femaRegion":"1", "lastEapExcerDate":"2024-09-05T12:00:00.000Z", "dataUpdated":"2025-03-17T12:00:00.000Z", "usaceDistrict":"New England District", "noConsequencesId":0, "secretaryAgricultureBuiltId":null, "nrcsWatershedAuthorizationId":null, "isAssociatedStructureId":"No", "fedRegulatedId":"Yes", "inundationNidAddedId":1, "damStatusId":2, "huc06":"010700", "doi_region":null, "doi_region_name":"North Atlantic-Appalachian", "doi_region_number":1, "thirtyYearAverage":2.6437, "tenthPercentile":2.403, "ninetiethPercentile":3.173 }, "id":8083021, "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/8083021?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/8083021?f=jsonld" }, { "rel":"alternate", "type":"text/html", "title":"This document as HTML", "href":"https://api.wwdh.internetofwater.app/collections/usace-edr/items/8083021?f=html" }, { "rel":"collection", "type":"application/json", "title":"USACE Access2Water API", "href":"https://api.wwdh.internetofwater.app/collections/usace-edr" } ] }