{ "lid": "ALNI2", "usgsId": "05587541", "reachId": "880648", "name": "Mississippi River at Mel Price (Alton) Lock and Dam", "description": "", "rfc": { "abbreviation": "NCRFC", "name": "North Central River Forecast Center" }, "wfo": { "abbreviation": "LSX", "name": "St. Charles" }, "state": { "abbreviation": "IL", "name": "Illinois" }, "county": "Madison", "timeZone": "CST6CDT", "latitude": 38.866388888889, "longitude": -90.146388888889, "pedts": { "observed": "HTIRG", "forecast": "HTIFF" }, "status": { "observed": { "primary": 4.64, "primaryUnit": "ft", "secondary": 79.5, "secondaryUnit": "kcfs", "floodCategory": "no_flooding", "validTime": "2026-08-30T19:30:00Z" }, "forecast": { "primary": 4.6, "primaryUnit": "ft", "secondary": 78.9, "secondaryUnit": "kcfs", "floodCategory": "no_flooding", "validTime": "2026-08-31T00:00:00Z" } }, "flood": { "stageUnits": "ft", "flowUnits": "cfs", "categories": { "major": { "stage": 34, "flow": -9999 }, "moderate": { "stage": 29, "flow": -9999 }, "minor": { "stage": 21, "flow": -9999 }, "action": { "stage": 19, "flow": -9999 } }, "lro": { "minorCS": "0.16", "moderateCS": "< 0.05", "majorCS": "< 0.05", "producedTime": "2026-08-28T20:02:41Z", "interval": "SON" }, "crests": { "historic": [ { "occurredTime": "1993-08-01T00:00:00Z", "stage": 42.72, "flow": 369500, "preliminary": "R", "olddatum": false }, { "occurredTime": "2019-06-09T03:00:00Z", "stage": 39.01, "flow": 0, "preliminary": "O", "olddatum": false }, { "occurredTime": "1844-06-18T00:00:00Z", "stage": 36.9, "flow": -9999, "preliminary": "O", "olddatum": true }, { "occurredTime": "1973-04-28T00:00:00Z", "stage": 36.89, "flow": 535000, "preliminary": "O", "olddatum": false }, { "occurredTime": "2016-01-01T06:00:00Z", "stage": 35.8, "flow": -9999, "preliminary": "O", "olddatum": false }, { "occurredTime": "1995-05-22T00:00:00Z", "stage": 35.1, "flow": 0, "preliminary": "O", "olddatum": false }, { "occurredTime": "2017-05-06T01:00:00Z", "stage": 34.86, "flow": 0, 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0, "preliminary": "O", "olddatum": false }, { "occurredTime": "2010-08-23T06:00:00Z", "stage": 21.09, "flow": 0, "preliminary": "O", "olddatum": false }, { "occurredTime": "2010-01-27T08:00:00Z", "stage": 21.02, "flow": 0, "preliminary": "O", "olddatum": false }, { "occurredTime": "2008-05-28T07:00:00Z", "stage": 21.02, "flow": 0, "preliminary": "O", "olddatum": false } ], "recent": [ { "occurredTime": "2026-05-01T06:00:00Z", "stage": 24.3, "flow": 419400, "preliminary": "O", "olddatum": false }, { "occurredTime": "2024-05-02T03:00:00Z", "stage": 23.62, "flow": 0, "preliminary": "O", "olddatum": false }, { "occurredTime": "2021-06-28T13:00:00Z", "stage": 23.17, "flow": 0, "preliminary": "O", "olddatum": false }, { "occurredTime": "2021-04-14T01:30:00Z", "stage": 22.9, "flow": 0, "preliminary": "O", "olddatum": false }, { "occurredTime": "2021-03-20T22:30:00Z", "stage": 25.04, "flow": 0, "preliminary": "O", "olddatum": false }, { "occurredTime": "2020-06-01T11:30:00Z", "stage": 25.14, 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"preliminary": "O", "olddatum": false }, { "occurredTime": "2017-05-06T01:00:00Z", "stage": 34.86, "flow": 0, "preliminary": "O", "olddatum": false }, { "occurredTime": "2017-04-09T19:30:00Z", "stage": 22.67, "flow": 0, "preliminary": "O", "olddatum": false }, { "occurredTime": "2016-01-12T05:00:00Z", "stage": 22.48, "flow": -9999, "preliminary": "O", "olddatum": false }, { "occurredTime": "2016-01-01T06:00:00Z", "stage": 35.8, "flow": -9999, "preliminary": "O", "olddatum": false }, { "occurredTime": "2015-12-19T11:00:00Z", "stage": 24.01, "flow": -9999, "preliminary": "O", "olddatum": false }, { "occurredTime": "2015-06-30T22:00:00Z", "stage": 32.27, "flow": -9999, "preliminary": "O", "olddatum": false }, { "occurredTime": "2014-07-11T14:30:00Z", "stage": 25.84, "flow": 0, "preliminary": "O", "olddatum": false }, { "occurredTime": "2013-06-04T03:00:00Z", "stage": 34.38, "flow": 0, "preliminary": "O", "olddatum": false }, { "occurredTime": "2013-05-23T00:30:00Z", "stage": 21.54, 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"preliminary": "O", "olddatum": false }, { "occurredTime": "2010-03-29T22:00:00Z", "stage": 26.61, "flow": 453127, "preliminary": "O", "olddatum": false }, { "occurredTime": "2010-01-27T08:00:00Z", "stage": 21.02, "flow": 0, "preliminary": "O", "olddatum": false }, { "occurredTime": "2009-11-21T00:00:00Z", "stage": 22.7, "flow": 0, "preliminary": "O", "olddatum": false }, { "occurredTime": "2009-11-02T15:00:00Z", "stage": 26.31, "flow": 0, "preliminary": "O", "olddatum": false }, { "occurredTime": "2009-06-20T08:00:00Z", "stage": 21.55, "flow": 343000, "preliminary": "O", "olddatum": false }, { "occurredTime": "2009-05-21T06:00:00Z", "stage": 27.24, "flow": 278000, "preliminary": "O", "olddatum": false }, { "occurredTime": "2009-04-01T00:00:00Z", "stage": 21.73, "flow": 347000, "preliminary": "O", "olddatum": false }, { "occurredTime": "2009-03-16T03:00:00Z", "stage": 22.66, "flow": 381245, "preliminary": "O", "olddatum": false }, { "occurredTime": "2008-09-18T07:00:00Z", "stage": 29.89, "flow": 0, "preliminary": "O", "olddatum": false }, { "occurredTime": "2008-08-01T23:00:00Z", "stage": 24.06, "flow": 0, "preliminary": "O", "olddatum": false }, { "occurredTime": "2008-06-30T03:00:00Z", "stage": 33.08, "flow": 0, "preliminary": "O", "olddatum": false }, { "occurredTime": "2008-05-28T07:00:00Z", "stage": 21.02, "flow": 0, "preliminary": "O", "olddatum": false }, { "occurredTime": "2008-05-10T00:00:00Z", "stage": 24.88, "flow": 0, "preliminary": "O", "olddatum": false }, { "occurredTime": "2008-04-13T12:00:00Z", "stage": 25.38, "flow": 0, "preliminary": "O", "olddatum": false }, { "occurredTime": "2008-03-21T03:00:00Z", "stage": 24.44, "flow": 0, "preliminary": "O", "olddatum": false }, { "occurredTime": "2007-05-11T15:00:00Z", "stage": 22.76, "flow": 0, "preliminary": "O", "olddatum": false }, { "occurredTime": "2005-01-06T21:30:00Z", "stage": 22.58, "flow": 379000, "preliminary": "O", "olddatum": false }, { "occurredTime": "2004-05-29T04:00:00Z", "stage": 22.16, "flow": 0, "preliminary": "O", "olddatum": false }, { "occurredTime": "2001-06-09T20:00:00Z", "stage": 28.9, "flow": 0, "preliminary": "O", "olddatum": false }, { "occurredTime": "2001-05-21T10:30:00Z", "stage": 25.91, "flow": 0, "preliminary": "O", "olddatum": false }, { "occurredTime": "2001-03-19T08:00:00Z", "stage": 21.5, "flow": 0, "preliminary": "O", "olddatum": false }, { "occurredTime": "1998-04-18T00:00:00Z", "stage": 28.1, "flow": 0, "preliminary": "O", "olddatum": false }, { "occurredTime": "1997-04-20T00:00:00Z", "stage": 25.7, "flow": 0, "preliminary": "O", "olddatum": false }, { "occurredTime": "1997-03-01T00:00:00Z", "stage": 26.7, "flow": 0, "preliminary": "O", "olddatum": false }, { "occurredTime": "1995-05-22T00:00:00Z", "stage": 35.1, "flow": 0, "preliminary": "O", "olddatum": false }, { "occurredTime": "1993-08-01T00:00:00Z", "stage": 42.72, "flow": 369500, "preliminary": "R", "olddatum": false }, { "occurredTime": "1993-04-18T00:00:00Z", "stage": 30.8, "flow": 0, "preliminary": "O", "olddatum": false }, { "occurredTime": "1986-10-09T00:00:00Z", "stage": 34.2, "flow": 0, "preliminary": "O", "olddatum": false }, { "occurredTime": "1986-05-23T00:00:00Z", "stage": 25.9, "flow": 308000, "preliminary": "O", "olddatum": false }, { "occurredTime": "1985-11-22T00:00:00Z", "stage": 27.7, "flow": 0, "preliminary": "O", "olddatum": false }, { "occurredTime": "1985-03-08T00:00:00Z", "stage": 29.6, "flow": 403000, "preliminary": "O", "olddatum": false }, { "occurredTime": "1984-06-28T00:00:00Z", "stage": 24.3, "flow": 0, "preliminary": "O", "olddatum": false }, { "occurredTime": "1984-04-25T00:00:00Z", "stage": 28.1, "flow": 305000, "preliminary": "O", "olddatum": false }, { "occurredTime": "1983-05-01T00:00:00Z", "stage": 33.21, "flow": 0, "preliminary": "O", "olddatum": false }, { "occurredTime": "1982-12-08T00:00:00Z", "stage": 32.44, "flow": 0, "preliminary": "O", "olddatum": false }, { "occurredTime": "1982-06-12T00:00:00Z", "stage": 26.2, "flow": 0, "preliminary": "O", "olddatum": false }, { "occurredTime": "1982-03-24T00:00:00Z", "stage": 25.6, "flow": 363000, "preliminary": "O", "olddatum": false }, { "occurredTime": "1981-07-30T00:00:00Z", "stage": 24.9, "flow": 0, "preliminary": "O", "olddatum": false }, { "occurredTime": "1973-04-28T00:00:00Z", "stage": 36.89, "flow": 535000, "preliminary": "O", "olddatum": false }, { "occurredTime": "1844-06-18T00:00:00Z", "stage": 36.9, "flow": -9999, "preliminary": "O", "olddatum": true } ] }, "lowWaters": { "historic": [] }, "impacts": [ { "stage": 42.7, "statement": "This is the RECORD FLOOD LEVEL that was reached on August 1 1993." }, { "stage": 42, "statement": "Near this height U.S. Highway 67 will be completely closed. (MoDOT)" }, { "stage": 40, "statement": "Railroad tracks from Wood River to Alton begin to flood." }, { "stage": 37.6, "statement": "Damage begins to Ardent Mills grain bins in Alton within a foot of this height." }, { "stage": 36.1, "statement": "This represents the height of the Lincoln Shields levee just below the Missouri side of the Clark bridge." }, { "stage": 35.5, "statement": "At this approximate stage, Mel Price Lock and Dam must close the lock to navigation. This happened on July 10, 1993." }, { "stage": 34.5, "statement": "Near this height, the southbound lanes of U.S. Highway 67 will begin flooding, forcing the detour of southbound traffic onto the northbound lanes." }, { "stage": 34.2, "statement": "Near this height water will begin flowing over Riverlands Way between Highway 67 and Mel Price Locks and Dam. This road is a part of the Consolidated North County levee, so this is the point when water begins gradually flowing onto the protected farmland and farm homes behind the levee." }, { "stage": 32.9, "statement": "Riverfront Park in Alton begins flooding." }, { "stage": 31.5, "statement": "Commercial basements in Alton begin to flood within a foot of this height." }, { "stage": 30.5, "statement": "Bloch Marine Service at the Harbor Point Yacht Club begins flooding within a foot of this level." }, { "stage": 29.9, "statement": "Route 100 at Alton closes within a foot of this height. Also at this level the north and south Wood River Levee structures are closed." }, { "stage": 29.3, "statement": "The North Wood River Levee must be closed at this level." }, { "stage": 28.8, "statement": "Highway 100 will begin flooding at Clifton Terrace Street within 2 feet of this height." }, { "stage": 28.5, "statement": "The South Wood River Levee must be closed at this level." }, { "stage": 27.9, "statement": "Missouri Highway 94 from Alta Villa Road to Feltes Drive will be closed near this height." }, { "stage": 26.6, "statement": "Within a foot of this height, outer road US 67 between Riverlands Way and the Lincoln Shields Access Road will close due to flooding." }, { "stage": 26.5, "statement": "Yachtview Drive begins flooding along the entrance to Harbor Point Yacht Club within a foot of this height." }, { "stage": 25, "statement": "Highway 94 and the east end of Harbor Point Road off of Highway 94 north of West Alton begin flooding within a foot or so of this height. Also, the access road to the Lincoln Shields area off Highway 67 just west of the Clark bridge begins flooding." }, { "stage": 24, "statement": "Alta Villa Road off of Highway 94 north of West Alton is closed within a foot of this height." }, { "stage": 23, "statement": "Dresser Island Drive floods within a foot of this level." }, { "stage": 20.8, "statement": "Unprotected farm land begins to flood" }, { "stage": 18, "statement": "Near this height, Mel Price Lock and Dam will go to \"open river\" conditions, lifting all gates out of the river." } ] }, "images": { "probability": { "weekint": { "stage": "https://water.noaa.gov/resources/probabilistic/exceedance/ALNI2.SSTG.prob.weekint.gif", "flow": "", "volume": "" }, "entperiod": { "stage": "https://water.noaa.gov/resources/probabilistic/exceedance/ALNI2.SSTG.exceed.90day.gif", "flow": "", "volume": "" }, "shortrange": "https://water.noaa.gov/resources/probabilistic/short_term/ALNI2.shortrange.hefs.png" }, "hydrograph": { "default": "https://water.noaa.gov/resources/hydrographs/alni2_hg.png", "floodcat": "https://water.noaa.gov/resources/hydrographs/alni2_record.png" }, "photos": [ { "id": "783318518730920430", "type": "Feature", "geometry": { "type": "Point", "coordinates": [ 38.866388888889, -90.146388888889 ] }, "properties": { "image": "https://water.noaa.gov/resources/photos/alni2/783318518730920430.jpeg", "caption": "Melvin Price Lock and Dam (looking upstream)" } }, { "id": "825285601957843438", "type": "Feature", "geometry": { "type": "Point", "coordinates": [ 38.866388888889, -90.146388888889 ] }, "properties": { "image": "https://water.noaa.gov/resources/photos/alni2/825285601957843438.jpeg", "caption": "Melvin Price Lock and Dam #26" } }, { "id": "867681851201884654", "type": "Feature", "geometry": { "type": "Point", "coordinates": [ 38.866388888889, -90.146388888889 ] }, "properties": { "image": "https://water.noaa.gov/resources/photos/alni2/867681851201884654.jpeg", "caption": "Melvin Price Lock and Dam (looking downstream)" } }, { "id": "906701959798526446", "type": "Feature", "geometry": { "type": "Point", "coordinates": [ 38.866388888889, -90.146388888889 ] }, "properties": { "image": "https://water.noaa.gov/resources/photos/alni2/906701959798526446.jpeg", "caption": "Melvin Price Lock and Dam #26" } }, { "id": "13551300595091116526", "type": "Feature", "geometry": { "type": "Point", "coordinates": [ 38.866388888889, -90.146388888889 ] }, "properties": { "image": "https://water.noaa.gov/resources/photos/alni2/13551300595091116526.jpeg", "caption": "Dresser Island Road on May 22, 2009 with an Alton tailwater stage of 25.8 feet." } }, { "id": "13569238070736327150", "type": "Feature", "geometry": { "type": "Point", "coordinates": [ 38.866388888889, -90.146388888889 ] }, "properties": { "image": "https://water.noaa.gov/resources/photos/alni2/13569238070736327150.jpeg", "caption": "Argosy casino parking on June 21, 2008 at an Alton tailwater stage of 31.6 feet." } }, { "id": "13585393955292451310", "type": "Feature", "geometry": { "type": "Point", "coordinates": [ 38.866388888889, -90.146388888889 ] }, "properties": { "image": "https://water.noaa.gov/resources/photos/alni2/13585393955292451310.jpeg", "caption": "Argosy casino parking on June 29, 2008 at an Alton tailwater stage of 33.1 feet." } }, { "id": "13601374910125576686", "type": "Feature", "geometry": { "type": "Point", "coordinates": [ 38.866388888889, -90.146388888889 ] }, "properties": { "image": "https://water.noaa.gov/resources/photos/alni2/13601374910125576686.jpeg", "caption": "ConAgra railroad tracks on June 21, 2008 at an Alton tailwater stage of 31.6 ft." } }, { "id": "13618346885712581102", "type": "Feature", "geometry": { "type": "Point", "coordinates": [ 38.866388888889, -90.146388888889 ] }, "properties": { "image": "https://water.noaa.gov/resources/photos/alni2/13618346885712581102.jpeg", "caption": "Yachtview Drive looking north on May 22, 2009 at a stage of 25.8 feet." } }, { "id": "13637055810498597358", "type": "Feature", "geometry": { "type": "Point", "coordinates": [ 38.866388888889, -90.146388888889 ] }, "properties": { "image": "https://water.noaa.gov/resources/photos/alni2/13637055810498597358.jpeg", "caption": "Access road to the Riverlands Environmental Demonstration Area on June 21, 2008 at 31.6 ft." } }, { "id": "13713158129857991150", "type": "Feature", "geometry": { "type": "Point", "coordinates": [ 38.866388888889, -90.146388888889 ] }, "properties": { "image": "https://water.noaa.gov/resources/photos/alni2/13713158129857991150.jpeg", "caption": "Harbor Point Road flooded on May 22, 2009 at an Alton tailwater of 25.8 feet." } }, { "id": "13730564086120452590", "type": "Feature", "geometry": { "type": "Point", "coordinates": [ 38.866388888889, -90.146388888889 ] }, "properties": { "image": "https://water.noaa.gov/resources/photos/alni2/13730564086120452590.jpeg", "caption": "Highway 94 north of West Alton, MO on May 22, 2009 at an Alton tailwater of 25.8 ft." } }, { "id": "13747571508072550894", "type": "Feature", "geometry": { "type": "Point", "coordinates": [ 38.866388888889, -90.146388888889 ] }, "properties": { "image": "https://water.noaa.gov/resources/photos/alni2/13747571508072550894.jpeg", "caption": "Jamie Circle at Harbor Point Yacht Club on May 22, 2009 at an Alton tailwater of 25.8 ft." } }, { "id": "13766450642412507630", "type": "Feature", "geometry": { "type": "Point", "coordinates": [ 38.866388888889, -90.146388888889 ] }, "properties": { "image": "https://water.noaa.gov/resources/photos/alni2/13766450642412507630.jpeg", "caption": "Downtown Alton businesses at State Street and West Broadway on June 29, 2008 at 33.1 ft." } }, { "id": "13783732117637829102", "type": "Feature", "geometry": { "type": "Point", "coordinates": [ 38.866388888889, -90.146388888889 ] }, "properties": { "image": "https://water.noaa.gov/resources/photos/alni2/13783732117637829102.jpeg", "caption": "Route 100 in downtown Alton on June 29, 2008 at an Alton tailwater stage of 33.1 feet." } }, { "id": "13801451619397800430", "type": "Feature", "geometry": { "type": "Point", "coordinates": [ 38.866388888889, -90.146388888889 ] }, "properties": { "image": "https://water.noaa.gov/resources/photos/alni2/13801451619397800430.jpeg", "caption": "Riverfront Park on June 21, 2008 at an Alton tailwater stage of 31.6 feet." } }, { "id": "9934679540468224494", "type": "Feature", "geometry": { "type": "Point", "coordinates": [ 38.866388888889, -90.146388888889 ] }, "properties": { "image": "https://water.noaa.gov/resources/photos/alni2/9934679540468224494.jpeg", "caption": "Sandbagging during 1993 flooding in downtown Alton, Illinois." } }, { "id": "9946227938728022510", "type": "Feature", "geometry": { "type": "Point", "coordinates": [ 38.866388888889, -90.146388888889 ] }, "properties": { "image": "https://water.noaa.gov/resources/photos/alni2/9946227938728022510.jpeg", "caption": "Floodwater pumping from behind sandbags in downtown Alton 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during the flood of 1993." } }, { "id": "9973799532824302062", "type": "Feature", "geometry": { "type": "Point", "coordinates": [ 38.866388888889, -90.146388888889 ] }, "properties": { "image": "https://water.noaa.gov/resources/photos/alni2/9973799532824302062.jpeg", "caption": "West Alton (foreground), downtown Alton (top), and Highway 67 (right) during 1993 flood." } } ] }, "dataAttribution": [ { "abbrev": "U.S. Army Corps of Engineers", "text": "RiverGages.com", "title": "", "url": "https://rivergages.mvr.usace.army.mil/WaterControl/new/layout.cfm" } ], "impactsLowWaters": [], "normalThreshold": null, "hydronotes": [ { "statement": "River forecasts for this location take into account past precipitation and the precipitation amounts expected approximately 24 hours into the future from the forecast issuance time.", "effective": "0401", "expiration": "0930" }, { "statement": "River forecasts for this location take into account past precipitation and the precipitation amounts expected approximately 48 hours into the future from the forecast issuance time.", "effective": "1001", "expiration": "0331" }, { "statement": "For the latest navigation status update from the U.S. Army Corps of Engineers-St. Louis District, click here.", "effective": "0101", "expiration": "1231" } ], "datums": { "vertical": { "value": [ { "label": "North American Vertical Datum of 1988", "abbrev": "NAVD88", "description": "A fixed reference for elevations determined by geodetic leveling. The datum was derived from a general adjustment of the first-order terrestrial leveling nets of the United States, Canada, and Mexico. In the adjustment, only the height of the primary tidal bench mark, referenced to the International Great Lakes Datum of 1985 (IGLD 85) local mean sea level height value, at Father Point, Rimouski, Quebec, Canada was held fixed, thus providing minimum constraint. NAVD 88 and IGLD 85 are identical. However, NAVD 88 bench mark values are given in Helmert orthometric height units while IGLD 85 values are in dynamic heights. See International Great Lakes Datum of 1985, National Geodetic Vertical Datum of 1929, and geopotential difference. NAVD 88 should not be used as Mean Sea Level.", "value": 395.04 } ] }, "horizontal": { "value": [] }, "notes": { "value": [] } }, "inundation": { "enabled": false, "url": "", "zeroDatum": null, "downloads": null, "siteSpecificInfo": "", "dataAttribution": [] }, "upstreamLid": "ALOI2", "downstreamLid": "EADM7", "inService": { "enabled": true, "message": "" }, "lowThreshold": null, "forecastReliability": "Forecasts are issued routinely year-round.", "TruncateObs": "-1", "TruncateFcst": "-1", "ObservedFloodCategory": "no_flooding", "ForecastFloodCategory": "no_flooding" }