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LOCATION.-- Lat 38°53'06", long 90°10'51" (NAD of 1927), in NE1/4 sec.14, T.5 N., R.10 W., Madison County, Hydrologic Unit 07110009, near right bank in downstream end of intermediate lock wall of lock and dam 26 at Alton, 300 ft downstream from Missouri & Illinois Bridge & Belt Railroad bridge, 7.7 mi upstream from Missouri River, and at mile 202.7 upstream from Ohio River. |
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DRAINAGE AREA.-- 171,500 mi2, approximately. |
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PERIOD OF RECORD.-- |
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SURFACE-WATER DISCHARGE AND STAGE |
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DISCHARGE: October 1927 to September 1986. Monthly discharge only for some periods, published in WSP 1308. |
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STAGE: Gage-height records at Grafton since 1879 and at Alton since January 1904 in reports of Mississippi River Commission, December 1890 to September 1893 and January 1917 to December 1939 in reports of National Weather Service. |
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SURFACE-WATER QUALITY |
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SPECIFIC CONDUCTANCE: Water years 1977. |
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WATER TEMPERATURE: Water years 1968-77. |
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GAGE.-- Water-stage recorder. Datum of gage is at mean sea level, NGVD of 1929 (levels by U.S. Army Corps of Engineers). Prior to Mar. 20, 1933, nonrecording gage at Grafton 15.3 mi upstream, at datum 403.79 ft higher. Mar. 20, 1933 to Jan. 4, 1937 and Nov. 11, 1937 to Jan. 31, 1938, nonrecording gage 300 ft upstream at datum 395.48 ft higher. Since July 11, 1940, auxiliary water-stage recorder 5.9 mi downstream; previously various combinations of gage were used. |
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REMARKS.-- Natural flow of stream affected by many reservoirs and navigation dams in upper Mississippi River basin. Floodwater from Missouri River overtops or breaches the levees at extreme high stages. Overflow from Missouri River occurred during various floods as shown in the following table:
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EXTREMES FOR PERIOD OF RECORD.-- |
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SURFACE-WATER DISCHARGE AND STAGE: Maximum discharge, 535,000 ft3/s, Apr. 29, 1973, includes undetermined amount of overflow from Missouri River; maximum elevation, 432.15 ft, Apr. 28, 1973; minimum discharge, 7,960 ft3/s, Nov. 7, 1948, result of temporary storage in pool of lock and dam 26. |
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EXTREMES OUTSIDE PERIOD OF RECORD.-- |
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SURFACE-WATER DISCHARGE AND STAGE: Flood of June 1844 reached a stage of 432.10 ft, present datum. |
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Table of Contents |
Introduction |
Station Descriptions |
Surface-Water Data |
Ground-Water Data |
Meteorological Data |
Biological Data |