PISCATAQUA RIVER BASIN
01072800 COCHECO RIVER NEAR ROCHESTER, NH
LOCATION.--Lat 43°16'26", long 70°58'27", Strafford County, Hydrologic Unit 01060003, on right bank, directly behind
Rochester Country Club, 0.6 mi south by southeast of Gonic, 2.5 mi south of Rochester City Hall, approximately
3.3 mi upstream from mouth of Isinglass River, and approximately 12.6 mi above mouth.
DRAINAGE AREA.-- 85.7 mi² (Revised).
PERIOD OF RECORD.--Discharge records: March 1995 to current year. Published as "at Rochester" prior to October 1996.
GAGE.--Water-stage recorder and crest stage gage. Elevation of gage is 125 ft above sea level, from topographic map.
REMARKS.--Records good except those for estimated daily discharges, which are fair. Some regulation by small hydro
plants, Sunrise and Baxter Lakes, City Dam No. 1, and the Rochester Reservoirs. Low flows diverted from Berrys
River (tributary to Isinglass River) to Rochester Reservoir (head of Howard Brook) then into the Rochester City
water supply system. Unknown amount of diverted flow enters the Cocheco River Basin above the gage.
EXTREMES FOR CURRENT YEAR.--Maximum discharge, 3090 ft³/s, October 22, gage height, 14.82 ft; minimum daily discharge,
9.9 ft³/s, October 6, and August 10 and 11.
DISCHARGE, CUBIC FEET PER SECOND, WATER YEAR OCTOBER 1996 TO SEPTEMBER 1997
DAILY MEAN VALUES
DAY OCT NOV DEC JAN FEB MAR APR MAY JUN JUL AUG SEP
1 16 165 176 e240 e115 343 579 283 60 13 14 e28
2 14 145 618 e215 112 276 433 233 60 11 14 e25
3 13 130 1060 210 100 343 393 207 57 16 13 e21
4 10 119 543 194 99 269 415 249 55 75 13 18
5 10 114 391 197 117 209 503 222 52 48 12 15
6 9.9 112 307 251 e125 288 517 192 48 34 11 14
7 10 111 260 232 e110 311 519 195 45 28 10 14
8 11 125 284 180 e95 211 561 170 42 23 10 20
9 32 156 366 e170 e90 e175 473 156 40 78 10 17
10 38 243 320 156 e85 e150 338 175 36 117 9.9 15
11 38 207 256 e145 e80 e135 261 192 32 65 9.9 16
12 30 162 233 e135 e75 e120 219 168 30 44 13 59
13 28 138 323 e125 e70 e110 316 148 31 33 16 73
14 26 128 347 e115 96 e115 385 144 30 29 26 65
15 20 e110 316 e105 99 e135 303 129 29 282 17 47
16 18 e98 303 e115 e80 e135 242 156 26 381 15 36
17 18 e96 409 e155 e80 119 220 179 23 186 14 30
18 16 95 953 e140 e80 108 511 147 25 114 12 27
19 19 97 765 e135 92 102 2240 130 38 83 11 23
20 104 102 745 e145 139 e100 1640 183 49 62 10 21
21 1640 100 588 e130 154 108 823 188 38 50 12 19
22 2730 92 412 e125 316 119 568 145 30 45 38 15
23 1390 86 335 e125 476 107 443 121 26 38 36 15
24 669 82 298 151 e380 e95 375 106 23 33 29 15
25 507 79 e340 169 e235 e90 313 101 21 31 22 15
26 375 153 e330 180 e175 216 271 102 20 27 19 12
27 271 333 e310 e160 213 382 229 92 18 25 17 13
28 229 233 e300 159 358 364 265 82 15 24 22 13
29 215 161 e280 e140 --- 455 482 73 14 21 24 16
30 185 135 e270 e130 --- 581 397 66 14 17 32 18
31 182 --- e250 e125 --- 766 --- 62 --- 16 33 ---
TOTAL 8873.9 4107 12688 4954 4246 7037 15234 4796 1027 2049 544.8 735
MEAN 286 137 409 160 152 227 508 155 34.2 66.1 17.6 24.5
MAX 2730 333 1060 251 476 766 2240 283 60 381 38 73
MIN 9.9 79 176 105 70 90 219 62 14 11 9.9 12
STATISTICS OF MONTHLY MEAN DATA FOR WATER YEARS 1995 - 1997, BY WATER YEAR (WY)
MEAN 189 233 254 259 225 236 360 165 45.4 79.5 17.1 14.1
MAX 286 329 409 359 295 253 508 268 63.7 161 24.7 24.5
(WY) 1997 1996 1997 1996 1996 1995 1997 1996 1996 1996 1996 1997
MIN 91.9 137 98.5 160 152 227 129 71.9 34.2 11.6 9.07 4.85
(WY) 1996 1997 1996 1997 1997 1996 1995 1995 1997 1995 1995 1995
SUMMARY STATISTICS FOR 1996 CALENDAR YEAR FOR 1997 WATER YEAR WATER YEARS 1995 - 1997
ANNUAL TOTAL 82050.3 66291.7
ANNUAL MEAN 224 182 189
HIGHEST ANNUAL MEAN 197 1996
LOWEST ANNUAL MEAN 182 1997
HIGHEST DAILY MEAN 2730 Oct 22 2730 Oct 22 2730 Oct 22 1996
LOWEST DAILY MEAN 9.4 Sep 12 a 9.9 Oct 6 2.2 Sep 4 1995
ANNUAL SEVEN-DAY MINIMUM 10 Sep 6 10 Aug 5 2.5 Sep 1 1995
INSTANTANEOUS PEAK FLOW 3090 Oct 22 3090 Oct 22 1996
INSTANTANEOUS PEAK STAGE 14.82 Oct 22 14.82 Oct 22 1996
10 PERCENT EXCEEDS 501 387 377
50 PERCENT EXCEEDS 130 112 93
90 PERCENT EXCEEDS 15 15 11
a Also occurred on August 10, 11.
e Estimated.
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