LOCATION.-- Lat 40°23'37", long 91°22'27" (NAD of 1927), in SE1/4 SW1/4 sec.30, T.65 N., R.4 W., Lee County, Hydrologic Unit 07080104, near right bank in tailwater of dam and powerplant of Union Electric Co. at Keokuk, 0.2 mi upstream from bridge on U.S. Highway 136, 2.7 mi upstream from Des Moines River, and at mile 364.2 upstream from Ohio River. |
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DRAINAGE AREA.-- 119,000 mi2, approximately. |
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PERIOD OF RECORD.-- |
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SURFACE-WATER DISCHARGE AND STAGE |
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DISCHARGE: January 1878 to current year. |
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GAGE.-- Water-stage recorder. Datum of gage is 477.41 ft above NGVD of 1929 (levels by U.S. Army Corps of Engineers). Jan. 1, 1878 to May 1913, nonrecording gage at Galland (formerly Nashville), 8 mi upstream; zero of gage was set to low-water mark of 1864, or 496.52 ft above NGVD of 1929. |
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REMARKS.-- Discharge computed from records of operation of turbines in powerplant and spillway gates in dam. Records provided by Union Electric Co. Minor flow regulation caused by powerplant since 1913 and navigation dams. Records for May 1913 to September 1937 adjusted for change in contents in Keokuk Reservoir, those after September 1937 unadjusted. |
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EXTREMES FOR PERIOD OF RECORD.-- |
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SURFACE-WATER DISCHARGE AND STAGE: Maximum discharge, 446,000 ft3/s, July 10, 1993, gage height, 27.58 ft; from floodmark; minimum daily discharge, 5,000 ft3/s, December 27, 1933. |
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EXTREMES OUTSIDE PERIOD OF RECORD.-- |
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SURFACE-WATER DISCHARGE AND STAGE: Flood of June 6, 1851, reached a stage of 21.0 ft, present site and datum, estimated as 13.5 ft at Galland, discharge, 360,000 ft3/s. |
DISCHARGE, IN CUBIC FEET PER SECOND, WATER YEAR OCTOBER 2001 TO SEPTEMBER 2002 DAILY MEAN VALUES |
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DAY | OCT | NOV | DEC | JAN | FEB | MAR | APR | MAY | JUN | JUL | AUG | SEP |
1 | 45500 | 44400 | 63000 | 33800 | 44700 | 61700 | 54500 | 186000 | 103000 | 112000 | 73500 | 93900 |
2 | 39800 | 47800 | 68400 | 34400 | 39400 | 58600 | 66800 | 176000 | 110000 | 111000 | 65500 | 85700 |
3 | 37500 | 48000 | 71600 | 33400 | 41400 | 53100 | 69800 | 169000 | 95000 | 115000 | 65500 | 82000 |
4 | 35400 | 56000 | 68400 | 33900 | 36100 | 41700 | 69400 | 159000 | 88900 | 116000 | 61400 | 74500 |
5 | 38200 | 52300 | 58400 | 34200 | 36000 | 37900 | 76400 | 153000 | 120000 | 119000 | 65200 | 67600 |
6 | 39600 | 47600 | 57200 | 35800 | 35200 | 37800 | 72400 | 145000 | 146000 | 116000 | 70000 | 67100 |
7 | 40000 | 43900 | 54500 | 41900 | 35100 | 40200 | 75500 | 143000 | 172000 | 114000 | 63600 | 67400 |
8 | 37800 | 49900 | 60700 | 43300 | 37000 | 53700 | 83500 | 137000 | 190000 | 110000 | 65500 | 65000 |
9 | 33900 | 45500 | 64600 | 42400 | 38800 | 62600 | 97600 | 137000 | 199000 | 110000 | 65000 | 63300 |
10 | 31200 | 43900 | 70600 | 45800 | 40800 | 76000 | 115000 | 135000 | 188000 | 106000 | 64100 | 67900 |
11 | 32000 | 43900 | 69100 | 49000 | 49000 | 76300 | 106000 | 142000 | 180000 | 104000 | 67300 | 71800 |
12 | 35900 | 42100 | 67900 | 52400 | 54600 | 74900 | 104000 | 179000 | 177000 | 96600 | 68600 | 70400 |
13 | 42600 | 41600 | 71900 | 50500 | 54800 | 71100 | 102000 | 169000 | 190000 | 89100 | 71900 | 72000 |
14 | 44800 | 44000 | 73100 | 49500 | 53900 | 73700 | 98600 | 167000 | 183000 | 85900 | 74200 | 76300 |
15 | 44800 | 41000 | 72800 | 49900 | 47900 | 82400 | 99600 | 155000 | 170000 | 75700 | 74200 | 76900 |
16 | 46100 | 41800 | 74500 | 49000 | 46200 | 76800 | 99300 | 146000 | 159000 | 76900 | 82500 | 74700 |
17 | 40600 | 45200 | 64500 | 49600 | 50500 | 82700 | 108000 | 140000 | 146000 | 76900 | 65700 | 75700 |
18 | 43700 | 44000 | 60800 | 48400 | 42200 | 79500 | 104000 | 142000 | 131000 | 75800 | 67800 | 74500 |
19 | 49400 | 46500 | 58400 | 42800 | 44200 | 75800 | 113000 | 142000 | 116000 | 85100 | 62700 | 72500 |
20 | 40500 | 44600 | 55800 | 39200 | 44000 | 76200 | 119000 | 139000 | 109000 | 87400 | 69500 | 64100 |
21 | 42000 | 41700 | 61300 | 40700 | 52800 | 73300 | 129000 | 135000 | 104000 | 84800 | 69500 | 63800 |
22 | 47000 | 43100 | 58500 | 40900 | 65100 | 61300 | 134000 | 133000 | 102000 | 90900 | 71200 | 62900 |
23 | 61200 | 40900 | 54100 | 38500 | 62700 | 69500 | 146000 | 136000 | 96500 | 88000 | 97400 | 58000 |
24 | 74500 | 41900 | 54600 | 42500 | 65200 | 64800 | 156000 | 136000 | 95500 | 86700 | 112000 | 58900 |
25 | 61800 | 45200 | 48200 | 37600 | 65500 | 66100 | 162000 | 140000 | 91500 | 79500 | 115000 | 50000 |
26 | 62500 | 51200 | 40200 | 39900 | 68600 | 62800 | 169000 | 135000 | 91100 | 80200 | 107000 | 48700 |
27 | 74000 | 48200 | 29100 | 43700 | 70900 | 64300 | 179000 | 126000 | 90400 | 74300 | 95500 | 42500 |
28 | 50600 | 54800 | 27700 | 48400 | 70000 | 64300 | 185000 | 116000 | 98000 | 85600 | 87900 | 46900 |
29 | 56400 | 60600 | 28400 | 51600 | --- | 63600 | 193000 | 111000 | 105000 | 78200 | 93100 | 52600 |
30 | 47900 | 59600 | 29200 | 51200 | --- | 56000 | 191000 | 101000 | 104000 | 79900 | 93600 | 51400 |
31 | 41900 | --- | 31000 | 51800 | --- | 52200 | --- | 93700 | --- | 77300 | 95000 | --- |
TOTAL | 1419100 | 1401200 | 1768500 | 1346000 | 1392600 | 1990900 | 3478400 | 4423700 | 3950900 | 2887800 | 2400900 | 1999000 |
MEAN | 45780 | 46710 | 57050 | 43420 | 49740 | 64220 | 115900 | 142700 | 131700 | 93150 | 77450 | 66630 |
MAX | 74500 | 60600 | 74500 | 52400 | 70900 | 82700 | 193000 | 186000 | 199000 | 119000 | 115000 | 93900 |
MIN | 31200 | 40900 | 27700 | 33400 | 35100 | 37800 | 54500 | 93700 | 88900 | 74300 | 61400 | 42500 |
AC-FT | 2815000 | 2779000 | 3508000 | 2670000 | 2762000 | 3949000 | 6899000 | 8774000 | 7837000 | 5728000 | 4762000 | 3965000 |
CFSM | 0.38 | 0.39 | 0.48 | 0.36 | 0.42 | 0.54 | 0.97 | 1.20 | 1.11 | 0.78 | 0.65 | 0.56 |
IN. | 0.44 | 0.44 | 0.55 | 0.42 | 0.44 | 0.62 | 1.09 | 1.38 | 1.24 | 0.90 | 0.75 | 0.62 |
STATISTICS OF MONTHLY MEAN DATA FOR WATER YEARS 1879 - 2002, BY WATER YEAR (WY) | ||||||||||||
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MEAN | 50850 | 51160 | 38710 | 36140 | 42910 | 80570 | 120200 | 109300 | 94620 | 75020 | 49960 | 47560 |
MAX | 221100 | 211300 | 125600 | 101600 | 95620 | 185400 | 250100 | 260700 | 227300 | 385800 | 223000 | 163300 |
(WY) | 1882 | 1882 | 1983 | 1973 | 1984 | 1973 | 1993 | 1888 | 1892 | 1993 | 1993 | 1993 |
MIN | 16060 | 16020 | 13450 | 14650 | 15790 | 21780 | 32930 | 27600 | 17400 | 16280 | 13030 | 15530 |
(WY) | 1934 | 1934 | 1934 | 1940 | 1899 | 1934 | 1895 | 1934 | 1934 | 1988 | 1936 | 1976 |
SUMMARY STATISTICS | FOR 2001 CALENDAR YEAR | FOR 2002 WATER YEAR | WATER YEARS 1879 - 2002 | |||
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ANNUAL TOTAL | 35518400 | 28459000 | ||||
ANNUAL MEAN | 97310 | 77970 | 66460 | |||
HIGHEST ANNUAL MEAN | 162500 | 1993 | ||||
LOWEST ANNUAL MEAN | 21540 | 1934 | ||||
HIGHEST DAILY MEAN | 345000 | May 15 | 199000 | Jun 9 | 434000 | Jul 10 1993 |
LOWEST DAILY MEAN | 27700 | Dec 28 | 27700 | Dec 28 | 5000 | Dec 27 1933 |
ANNUAL SEVEN-DAY MINIMUM | 33400 | Dec 25 | 30500 | Dec 27 | 8270 | Dec 25 1933 |
MAXIMUM PEAK FLOW | 446000 | Jul 10 1993 | ||||
MAXIMUM PEAK STAGE | 27.58 | Jul 10 1993a | ||||
ANNUAL RUNOFF (AC-FT) | 70450000 | 56450000 | 48150000 | |||
ANNUAL RUNOFF (CFSM) | 0.82 | 0.66 | 0.56 | |||
ANNUAL RUNOFF (INCHES) | 11.10 | 8.90 | 7.59 | |||
10 PERCENT EXCEEDS | 212000 | 140000 | 134000 | |||
50 PERCENT EXCEEDS | 60600 | 67600 | 51000 | |||
90 PERCENT EXCEEDS | 38100 | 40200 | 23000 |
a From floodmark. |
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Table of Contents |
Introduction |
Station Descriptions |
Surface-Water Data |
Ground-Water Data |
Meteorological Data |
Biological Data |