11270900 MERCED RIVER BELOW MERCED FALLS DAM, NEAR SNELLING, CA
LOCATION.-Lat 37°31'18", long 120°19'53", in SE 1/4 SW 1/4 sec.4, T.5 S., R.15 E., Merced County,
Hydrologic Unit 18040008, on right bank, 0.1 mi south of Merced Falls, 0.2 mi downstream from Merced Falls Dam,
and 5.8 mi east of Snelling.
DRAINAGE AREA.-1,061 mi2.
PERIOD OF RECORD.-April 1901 to current year. Records for water years 1914-16 incomplete, yearly estimates
published in WSP 1315-A. Published as "near Merced Falls" 1901-13; as "at Exchequer" 1916-64.
REVISED RECORDS.-WSP 1315-A: 1901-9, 1911(M). WSP 1515: 1918-20, 1942-43 (published as station 11270000). WSP
1930: Drainage area.
GAGE.-Water-stage recorder. Datum of gage is 310.55 ft above sea level. See WSP 1930 for history of changes prior
to Oct. 1, 1964.
REMARKS.-Merced Falls Dam diverts water to Northside Canal for irrigation downstream from station. Flow regulated
by Exchequer (station 11269700), McSwain (station 11270610), and Merced Falls powerplants, Lake McClure (station
11269500) since 1926, enlarged 1967, and McSwain Reservoir (station 11270600) since 1966, capacity, 9,200
acre-ft.
COOPERATION.-Records were provided by Pacific Gas and Electric Company, under general supervision of the U.S.
Geological Survey, in connection with a Federal Energy Regulatory Commission project.
EXTREMES FOR PERIOD OF RECORD (water years 1901-13, 1916-99).-Maximum discharge observed, 47,700
ft3/s, Jan. 31, 1911, gage height, 23.3 ft, site and datum then in use; no flow for part of Nov. 21,
1901. Maximum discharge since construction of Exchequer Dam in 1926, 46,200 ft3/s, Dec. 4, 1950, gage
height, 22.6 ft, from floodmarks, site and datum then in use, from rating curve extended above
16,000 ft3/s on basis of computation of peak flow over dam; minimum daily, 3.4 ft3/s,
Mar. 5, 1966.
DISCHARGE, CUBIC FEET PER SECOND, WATER YEAR OCTOBER 1998 TO SEPTEMBER 1999
DAILY MEAN VALUES
DAY OCT NOV DEC JAN FEB MAR APR MAY JUN JUL AUG SEP
1 2370 326 294 437 502 978 1020 2390 1760 1750 1760 1230
2 2560 331 294 438 498 981 1000 2450 1620 1800 1730 1160
3 2560 332 294 434 497 1280 1090 2480 1530 1850 1690 1120
4 2560 305 374 433 497 1350 1130 2450 1540 1890 1660 1070
5 2570 307 451 431 498 1250 1140 2440 1550 1960 1620 1080
6 2560 307 448 431 498 1260 1130 2710 1460 1950 1550 1110
7 2550 309 447 430 514 1260 1070 2750 1420 1900 1520 1140
8 2560 308 447 461 1200 1250 946 2650 1410 1850 1520 1160
9 2580 304 447 507 2470 1070 791 2450 1420 1830 1450 1170
10 2570 308 447 503 2770 1240 717 2150 1360 1790 1370 1130
11 2580 307 447 503 2780 1240 1160 2170 1420 1780 1400 1060
12 2590 303 445 502 2480 1240 1630 2280 1480 1820 1450 1060
13 2650 303 446 497 1790 1250 1830 2380 1640 1860 1510 1080
14 2650 303 447 500 1530 1240 1840 1970 1800 1870 1540 1040
15 2650 307 447 502 1530 1230 1830 1650 1830 1880 1500 1030
16 2060 307 452 502 1540 1230 2110 1570 1750 1910 1430 987
17 1750 310 441 502 1770 1090 2230 1520 1650 1930 1370 962
18 1440 302 431 502 2050 982 2280 1560 1630 1920 1380 941
19 1070 301 424 502 2350 978 2350 1580 1630 1880 1470 904
20 982 305 419 514 2760 981 2390 1610 1620 1800 1500 896
21 974 299 483 1150 2490 1010 2870 1590 1710 1780 1520 892
22 974 300 555 2090 2020 1020 3340 1560 1810 1740 1550 878
23 973 300 550 2080 1720 1010 3370 1510 1800 1720 1530 930
24 975 304 483 2080 1500 1010 3250 1530 1830 1750 1490 960
25 978 300 437 2070 1500 958 2730 1580 1810 1770 1480 959
26 978 301 434 1570 1490 954 2420 1570 1800 1770 1460 960
27 979 299 432 1010 1200 973 2370 1520 1840 1740 1420 962
28 980 297 432 999 981 984 2210 1500 1840 1710 1390 949
29 789 297 432 708 --- 983 1990 1530 1800 1710 1380 945
30 616 295 432 502 --- 1040 2200 1580 1740 1740 1280 878
31 459 --- 434 498 --- 1080 --- 1700 --- 1760 1220 ---
TOTAL 55537 9177 13446 24288 43425 34402 56434 60380 49500 56410 46140 30643
MEAN 1792 306 434 783 1551 1110 1881 1948 1650 1820 1488 1021
MAX 2650 332 555 2090 2780 1350 3370 2750 1840 1960 1760 1230
MIN 459 295 294 430 497 954 717 1500 1360 1710 1220 878
AC-FT 110200 18200 26670 48180 86130 68240 111900 119800 98180 111900 91520 60780
a 8690 8660 8600 9220 9070 9500 8810 8980 8910 8500 8840 9120
b 116000 .00 2740 41460 84130 70190 108300 118300 98120 111800 85860 63320
STATISTICS OF MONTHLY MEAN DATA FOR WATER YEARS 1901 - 1925, BY WATER YEAR (WY)
OCT NOV DEC JAN FEB MAR APR MAY JUN JUL AUG SEP
MEAN 224 222 396 1095 1290 2102 2644 4362 3719 1261 306 144
MAX 1522 531 1676 4409 3232 6995 5749 6768 8225 5867 958 302
(WY) 1905 1910 1910 1911 1909 1907 1907 1922 1906 1906 1906 1904
MIN 49.4 58.5 83.7 100 208 314 774 1478 212 61.3 29.9 20.5
(WY) 1914 1922 1906 1918 1913 1924 1912 1924 1924 1924 1924 1924
SUMMARY STATISTICS WATER YEARS 1901 - 1925
ANNUAL MEAN 1443
HIGHEST ANNUAL MEAN 2937 1907
LOWEST ANNUAL MEAN 348 1924
HIGHEST DAILY MEAN 37200 Jan 30 1911
LOWEST DAILY MEAN 1.0 Nov 21 1901
ANNUAL SEVEN-DAY MINIMUM 20 Sep 4 1924
INSTANTANEOUS PEAK FLOW 47700 Jan 31 1911
INSTANTANEOUS PEAK STAGE 23.30 Jan 31 1911
ANNUAL RUNOFF (AC-FT) 1045000
10 PERCENT EXCEEDS 4340
50 PERCENT EXCEEDS 488
90 PERCENT EXCEEDS 80
STATISTICS OF MONTHLY MEAN DATA FOR WATER YEARS 1927 - 1964, BY WATER YEAR (WY)
OCT NOV DEC JAN FEB MAR APR MAY JUN JUL AUG SEP
MEAN 223 57.8 267 402 694 1059 1892 3143 2737 1739 1400 884
MAX 638 385 4698 3869 3155 5375 3876 7249 7426 2384 1713 1313
(WY) 1945 1951 1951 1956 1938 1938 1958 1952 1938 1938 1963 1952
MIN 20.8 25.2 26.0 20.7 35.1 33.3 275 1049 1090 210 171 17.2
(WY) 1932 1932 1934 1940 1960 1948 1948 1955 1934 1931 1961 1931
SUMMARY STATISTICS WATER YEARS 1927 - 1964
ANNUAL MEAN 1210
HIGHEST ANNUAL MEAN 2738 1938
LOWEST ANNUAL MEAN 360 1931
HIGHEST DAILY MEAN 24000 Dec 4 1950
LOWEST DAILY MEAN 4.5 Feb 11 1960
ANNUAL SEVEN-DAY MINIMUM 8.7 Jan 12 1940
INSTANTANEOUS PEAK FLOW 46200 Dec 4 1950
INSTANTANEOUS PEAK STAGE 22.60 Dec 4 1950
ANNUAL RUNOFF (AC-FT) 876500
10 PERCENT EXCEEDS 2510
50 PERCENT EXCEEDS 1150
90 PERCENT EXCEEDS 38
STATISTICS OF MONTHLY MEAN DATA FOR WATER YEARS 1968 - 1999, BY WATER YEAR (WY)
OCT NOV DEC JAN FEB MAR APR MAY JUN JUL AUG SEP
MEAN 900 387 567 812 1150 1345 1844 2289 2331 2135 1744 1389
MAX 3143 1396 2451 7368 6686 4680 5278 5701 6975 5177 2761 3049
(WY) 1984 1970 1983 1997 1997 1983 1983 1982 1983 1983 1983 1983
MIN 76.4 118 120 133 113 139 394 528 813 922 636 83.1
(WY) 1978 1969 1969 1977 1977 1977 1991 1977 1977 1977 1977 1977
SUMMARY STATISTICS FOR 1998 CALENDAR YEAR FOR 1999 WATER YEAR WATER YEARS 1968 - 1999
ANNUAL TOTAL 884195 479782
ANNUAL MEAN 2422 1314 1409
HIGHEST ANNUAL MEAN 3779 1983
LOWEST ANNUAL MEAN 363 1977
HIGHEST DAILY MEAN 5520 Jul 9 3370 Apr 23 8020 Jan 4
1997
LOWEST DAILY MEAN 207 Jan 1 294 Dec 1 46 Oct 3
1968
ANNUAL SEVEN-DAY MINIMUM 207 Jan 1 296 Nov 27 74 Oct 12
1977
INSTANTANEOUS PEAK FLOW 4800 Apr 22 9360 Jun 1
1969
INSTANTANEOUS PEAK STAGE 9.51 Apr 22 12.40 Jun 1
1969
ANNUAL RUNOFF (AC-FT) 1754000 951600 1021000
10 PERCENT EXCEEDS 4280 2380 2910
50 PERCENT EXCEEDS 2590 1280 1190
90 PERCENT EXCEEDS 307 428 185
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