ROANOKE RIVER BASIN 02056000 ROANOKE RIVER AT NIAGARA, VA LOCATION.--Lat 37 degrees 15'18", long 79 degrees 52'18", Roanoke County, Hydrologic Unit 03010101, on right bank 200 ft downstream from powerplant of Appalachian Power Company at Niagara, 2 mi downstream from Tinker Creek, 2.1 mi southeast of Vinton, and at mile 355.3. DRAINAGE AREA.--512 mi2. PERIOD OF RECORD.--July 1926 to current year. REVISED RECORDS.--WSP 972: 1927(M), 1929(M), 1934(M), 1937(M). WSP 1303: 1928, 1930, 1933-38, 1940. WSP 2104: Drainage area. WDR VA-72-1: 1928(M), 1930(M), 1933(M), 1935-36(M), 1938(M), 1940, 1944-45(M), 1948- 49(M), 1951(M), 1955(M), 1960(M), 1967(M), 1969(M). GAGE.--Water-stage recorder. Datum of gage is 820.15 ft above sea level (levels by U.S. Army Corps of Engineers). REMARKS.--Records good except those for periods with ice effect, Dec. 12-13, Jan. 8-12, and Feb. 2-6, which are poor. Flow regulated by dam and powerplant 200 ft upstream from station. Maximum discharge, 52,300 ft3/s, from rating curve extended above 12,000 ft3/s on basis of slope-area measurements at gage heights 18.98 ft and 25.30 ft. Minimum gage height, 0.17 ft, Aug. 25, 1971. Several measurements of water temperature were made during the year. Water-quality records for some prior periods have been collected at this location. EXTREMES FOR CURRENT YEAR.--Peak discharges equal to or greater than base discharge of 3,500 ft3/s and maximum (*): Discharge Gage height Discharge Gage height Date Time (ft3/s) (ft) Date Time (ft3/s) (ft) Jan. 19 1115 *19,000 *15.73 June 10 1145 7,530 10.70 Jan. 27 1515 5,680 9.48 Aug. 13 0030 5,670 9.47 Feb. 9 1230 5,400 9.28 Sep. 4 1245 5,710 9.50 Mar. 20 0145 4,030 8.18 Sep. 6 2400 16,800 14.96 June 9 1630 9,210 11.64 Sep. 11 0830 5,960 9.68 Minimum discharge, 37 ft3/s, Oct. 29, gage height, 1.05 ft, result of dam closure; minimum daily, 137 ft3/s, Nov. 27. DISCHARGE, CUBIC FEET PER SECOND, WATER YEAR OCTOBER 1995 TO SEPTEMBER 1996 DAILY MEAN VALUES DAY OCT NOV DEC JAN FEB MAR APR MAY JUN JUL AUG SEP 1 145 159 388 228 868 463 1340 543 376 313 248 265 2 145 178 367 304 e760 460 1120 491 352 474 240 254 3 144 175 291 313 e630 449 932 441 324 397 212 400 4 202 147 263 302 e520 412 840 411 494 319 240 1460 5 815 158 243 290 e500 389 754 501 357 306 231 597 6 575 154 205 266 e540 401 684 1040 320 299 259 9810 7 280 270 260 237 591 442 650 833 412 270 254 5820 8 235 250 224 e220 644 424 594 771 542 319 241 1740 9 200 188 275 e220 4330 377 560 710 3830 548 636 1110 10 182 199 242 e230 3320 378 509 617 4880 353 245 835 11 175 334 195 e230 2370 363 472 643 3010 286 222 2190 12 155 369 e190 e250 1910 349 448 568 1880 264 2160 1150 13 158 312 e200 297 1350 340 450 496 1270 253 3460 1160 14 190 272 217 310 1100 316 451 448 918 281 1100 863 15 172 198 216 563 938 354 449 469 784 557 715 696 16 181 225 267 1040 854 382 404 1090 638 475 536 852 17 156 250 289 830 747 473 407 1520 590 342 449 1300 18 159 201 338 1950 630 477 380 1040 512 297 404 954 19 144 218 774 14200 584 1930 356 791 517 412 385 764 20 202 205 1200 4330 638 3110 354 625 1040 326 329 640 21 255 177 762 1910 620 1770 404 521 679 271 356 552 22 239 183 556 1290 621 1230 377 465 514 255 356 561 23 200 182 461 998 653 973 338 418 408 240 294 472 24 179 186 380 902 648 829 341 387 472 229 327 432 25 166 178 344 854 606 734 330 509 450 235 354 415 26 161 176 327 709 576 648 318 430 410 249 423 401 27 174 137 296 3930 557 554 315 483 350 248 330 404 28 161 176 274 2560 541 1070 327 688 334 227 316 487 29 139 727 216 1600 509 1810 317 556 321 233 313 652 30 154 522 241 1200 --- 1720 527 484 324 233 296 462 31 149 --- 224 1030 --- 1390 --- 408 --- 228 277 --- TOTAL 6592 7106 10725 43593 29155 25017 15748 19397 27308 9739 16208 37698 MEAN 213 237 346 1406 1005 807 525 626 910 314 523 1257 MAX 815 727 1200 14200 4330 3110 1340 1520 4880 557 3460 9810 MIN 139 137 190 220 500 316 315 387 320 227 212 254 CFSM .42 .46 .68 2.75 1.96 1.58 1.03 1.22 1.78 .61 1.02 2.45 IN. .48 .52 .78 3.17 2.12 1.82 1.14 1.41 1.98 .71 1.18 2.74 e Estimated. ROANOKE RIVER BASIN 02056000 ROANOKE RIVER AT NIAGARA, VA--Continued STATISTICS OF MONTHLY MEAN DATA FOR WATER YEARS 1927 - 1996, BY WATER YEAR (WY) OCT NOV DEC JAN FEB MAR APR MAY JUN JUL AUG SEP MEAN 357 370 471 636 760 910 831 567 421 295 346 322 MAX 1722 2100 2065 1941 1756 2846 3661 1447 1550 1396 2456 2051 (WY) 1938 1986 1949 1937 1994 1993 1987 1958 1972 1949 1940 1928 MIN 86.0 101 115 110 117 210 157 193 158 109 92.2 84.0 (WY) 1931 1942 1966 1966 1934 1981 1942 1930 1966 1930 1956 1954 SUMMARY STATISTICS FOR 1995 CALENDAR YEAR FOR 1996 WATER YEAR WATER YEARS 1927 - 1996 ANNUAL TOTAL 164754 248286 ANNUAL MEAN 451 678 523 HIGHEST ANNUAL MEAN 984 1949 LOWEST ANNUAL MEAN 198 1981 HIGHEST DAILY MEAN 11300 Jan 15 14200 Jan 19 19700 Nov 4 1985 LOWEST DAILY MEAN 128 Sep 14 137 Nov 27 8.0 Oct 9 1954 ANNUAL SEVEN-DAY MINIMUM 131 Sep 9 157 Oct 26 67 Jan 28 1966 INSTANTANEOUS PEAK FLOW 19000 Jan 19 52300 Nov 4 1985 INSTANTANEOUS PEAK STAGE 15.73 Jan 19 a25.30 Nov 4 1985 INSTANTANEOUS LOW FLOW b37 Oct 29 1.0 cOct 16 1956 ANNUAL RUNOFF (CFSM) .88 1.32 1.02 ANNUAL RUNOFF (INCHES) 11.97 18.04 13.87 10 PERCENT EXCEEDS 779 1200 985 50 PERCENT EXCEEDS 271 404 312 90 PERCENT EXCEEDS 156 190 136 a From floodmark. b Result of dam closure. c Also Oct. 20, 1956, and Nov. 25, 26, 1990.