LOCATION.-- Lat 41°38'53", long 87°33'50" (NAD of 1927), in SE1/4SE1/4 sec.36, T.37 N., R.14 E., Cook County, Hydrologic Unit 07120003, on right bank, 0.7 mi downstream of 130th Street in Chicago, and 1100 ft below the downstream lock gates at the Thomas J. O'Brien Lock and Dam, and at mile 6.9. | |
DRAINAGE AREA.-- Indeterminate. | |
PERIOD OF RECORD.-- | |
SURFACE-WATER DISCHARGE AND STAGE | |
DISCHARGE: October 1996 to cuurent year. | |
GAGE.-- Water stage recorder, acoustical flowmeter, and phone telemeter. Datum of gage is 579.48 ft above NGVD of 1929 (Chicago City datum). | |
REMARKS.-- This gaging station provides flow data to determine Illinois' diversion of Lake Michigan water. A U.S. Supreme Court Decree limits Illinois' diversion to an average of 3,200 ft3/s. Illinois' diversion includes water diverted from the lake for domestic water supply, for navigation, and water-quality improvement in the Chicago Sanitary and Ship Canal system, and stormwater runoff from a 673 mi2 diverted watershed area. Estimated daily discharges determined from regression equations between USGS mean daily discharges and mean daily discharges for the Obrien Lock and Dam as reported by the Metropolitan Water Reclamation District. | |
EXTREMES FOR PERIOD OF RECORD.-- --Maximum daily discharge, 1069 ft3/s (estimated), June 21,1997; mimimum daily, -769 ft3/s, Feb. 21, 1997, due to regulation to prevent flooding. | |
REMARKS FOR CURRENT YEAR.--Records fair except those for estimated daily discharges, which are poor. | |
| Discharge, cubic feet per second, WATER YEAR OCTOBER 2001 TO SEPTEMBER 2002
DAILY MEAN VALUES | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| DAY | OCT | NOV | DEC | JAN | FEB | MAR | APR | MAY | JUN | JUL | AUG | SEP |
| 1 | 62 | 54 | 4.0 | 13 | -17 | 31 | 83 | 132 | 111 | e142 | 499 | 291 |
| 2 | 186 | 9.2 | 18 | 31 | 17 | 40 | 7.5 | 23 | -202 | e136 | 588 | 374 |
| 3 | 134 | -43 | 59 | 9.9 | -18 | -6.5 | -82 | 60 | 12 | e154 | 625 | 220 |
| 4 | 122 | 20 | -2.3 | 57 | 21 | -30 | -56 | -26 | 415 | 222 | 614 | 266 |
| 5 | 235 | 32 | -16 | -7.8 | 38 | -21 | -56 | -124 | -64 | 288 | 453 | 262 |
| 6 | 91 | -5.7 | 130 | -96 | 40 | 21 | 54 | 112 | -128 | 169 | 393 | 149 |
| 7 | 130 | -45 | 35 | 52 | -70 | 16 | 31 | 64 | e184 | 314 | 392 | 140 |
| 8 | 152 | 29 | 1.7 | 0.08 | -58 | -34 | 33 | 77 | e176 | 200 | 349 | 238 |
| 9 | 67 | 52 | 56 | -45 | -17 | -90 | -37 | 35 | e185 | 322 | 481 | 136 |
| 10 | 148 | 84 | -17 | 5.4 | -50 | -34 | -12 | -53 | e53 | 278 | 354 | 190 |
| 11 | 135 | 103 | 31 | -5.5 | 1.8 | 22 | -59 | -73 | e316 | 239 | 388 | 229 |
| 12 | 114 | -73 | -16 | -26 | -14 | -12 | 15 | 19 | e63 | 373 | 340 | 225 |
| 13 | 23 | 1.1 | -4.6 | -33 | 19 | -8.7 | -53 | -82 | e63 | 117 | 595 | 200 |
| 14 | 15 | 270 | -25 | -32 | 34 | -58 | -101 | 25 | e32 | 144 | 234 | 164 |
| 15 | 21 | 46 | 75 | -40 | 36 | -20 | 0.12 | 51 | e65 | 297 | 335 | 225 |
| 16 | 64 | 68 | 70 | -68 | 34 | 51 | -100 | 93 | e78 | 263 | 339 | 165 |
| 17 | 56 | -166 | 48 | -17 | 18 | 41 | -90 | 11 | -248 | 117 | 217 | 173 |
| 18 | 147 | 58 | 18 | -15 | -6.6 | 61 | -116 | 60 | -60 | 245 | 293 | 38 |
| 19 | 43 | -13 | 42 | 11 | 30 | 63 | -67 | 16 | -14 | 250 | 438 | 277 |
| 20 | 101 | 50 | 34 | 18 | 26 | 21 | 98 | 45 | 78 | 350 | 353 | 195 |
| 21 | -20 | 72 | 32 | -23 | -19 | -22 | -8.0 | 103 | 48 | 260 | 169 | 194 |
| 22 | 278 | 92 | 67 | 22 | -18 | 13 | 57 | 21 | -119 | 141 | 26 | 144 |
| 23 | 401 | 75 | -9.1 | 6.0 | 33 | 43 | 103 | -3.6 | 148 | 314 | 774 | 129 |
| 24 | 356 | 127 | -7.5 | 42 | -23 | 12 | 24 | -93 | 328 | 296 | 290 | 123 |
| 25 | 19 | 31 | 11 | -34 | -89 | 55 | -49 | 152 | e198 | 281 | 349 | 165 |
| 26 | 2.3 | 107 | 33 | 2.3 | -67 | 69 | -13 | -1.4 | e53 | 273 | 320 | 97 |
| 27 | 38 | 41 | 31 | -42 | -39 | 35 | 207 | -130 | e92 | 81 | 350 | 117 |
| 28 | 50 | 0.35 | 15 | -66 | -26 | 7.6 | -2.0 | -26 | e104 | 212 | 374 | 89.0 |
| 29 | 106 | 76 | -18 | 52 | --- | -34 | 83 | -16 | e101 | 230 | 347 | 38.0 |
| 30 | 253 | 17 | 21 | -51 | --- | -51 | 22 | -37 | e106 | 387 | 367 | 16 |
| 31 | 73 | --- | -30 | 44 | --- | -14 | --- | -73 | --- | 447 | 310 | --- |
| TOTAL | 3602.3 | 1168.95 | 686.2 | -235.62 | -183.8 | 166.4 | -83.38 | 361.0 | 2174 | 7542 | 11956 | 5269.0 |
| MEAN | 116 | 39.0 | 22.1 | -7.60 | -6.56 | 5.37 | -2.78 | 11.6 | 72.5 | 243 | 386 | 176 |
| MAX | 401 | 270 | 130 | 57 | 40 | 69 | 207 | 152 | 415 | 447 | 774 | 374 |
| MIN | -20 | -166 | -30 | -96 | -89 | -90 | -116 | -130 | -248 | 81 | 26 | 16 |
| e Estimated |
| STATISTICS OF MONTHLY MEAN DATA FOR WATER YEARS 1997 - 2002, BY WATER YEAR (WY) | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| MEAN | 212 | 60.4 | 50.3 | 50.8 | 44.1 | 53.1 | 72.6 | 81.8 | 244 | 368 | 385 | 326 |
| MAX | 490 | 81.0 | 68.4 | 79.5 | 63.8 | 95.5 | 107 | 150 | 435 | 559 | 567 | 451 |
| (WY) | 1997 | 2001 | 2000 | 1997 | 1998 | 1997 | 1998 | 1997 | 1997 | 1998 | 1998 | 1998 |
| MIN | 74.6 | 39.0 | 22.1 | -7.60 | -6.56 | 5.37 | -2.78 | 11.6 | 72.5 | 146 | 259 | 176 |
| (WY) | 2001 | 2002 | 2002 | 2002 | 2002 | 2002 | 2002 | 2002 | 2002 | 2001 | 2001 | 2002 |
| SUMMARY STATISTICS | FOR 2001 CALENDAR YEAR | FOR 2002 WATER YEAR | WATER YEARS 1997 - 2002 | |||
|---|---|---|---|---|---|---|
| ANNUAL TOTAL | 41333.28 | 32423.05 | ||||
| ANNUAL MEAN | 113 | 88.8 | 163 | |||
| HIGHEST ANNUAL MEAN | 238 | 1997 | ||||
| LOWEST ANNUAL MEAN | 88.8 | 2002 | ||||
| HIGHEST DAILY MEAN | 766 | Aug 31 | 774 | Aug 23 | 1069 A | Jun 21 1997 |
| LOWEST DAILY MEAN | -171 | Jul 14 | -248 | Jun 17 | -769 B | Feb 21 1997 |
| ANNUAL SEVEN-DAY MINIMUM | -0.50 | Nov 2 | -75 | Apr 13 | -98 B | Feb 21 1997 |
| 10 PERCENT EXCEEDS | 284 | 314 | 453 | |||
| 50 PERCENT EXCEEDS | 75 | 43 | 85 | |||
| 90 PERCENT EXCEEDS | -8.1 | -50 | 8.2 | |||
|