11180825 SAN LORENZO CREEK ABOVE DON CASTRO RESERVOIR, NEAR CASTRO VALLEY, CA
LOCATION.-Lat 37°41'43", long 122°02'38", in San Lorenzo Grant, Alameda County, Hydrologic Unit
18050004, on right bank at Interstate Highway 580, 0.3 mi southeast of Independent School, and 2.2 mi east of
Castro Valley.
DRAINAGE AREA.-18.0 mi2.
WATER-DISCHARGE RECORDS
PERIOD OF RECORD.-October 1980 to September 1994, October 1997 to current year.
GAGE.-Water-stage recorder. Elevation of gage is 260 ft above sea level, from topographic map. October 1980 to
September 1994 at site 250 ft downstream at same datum.
REMARKS.-Records good except for estimated daily discharges, which are fair. Some regulation of low flow by ponds
upstream from station.
EXTREMES FOR PERIOD OF RECORD.-Maximum discharge, 3,890 ft3/s, Feb. 3, 1998, gage height, 15.48 ft; no
flow for many days in some years.
EXTREMES FOR CURRENT YEAR.-Peak discharges greater than base discharge of 275 ft3/s, or maximum:
Discharge Gage height Discharge Gage height
Date Time (ft3/s) (ft) Date Time (ft3/s) (ft)
Feb. 7 1145 1,260 8.88 Feb. 17 0145 405 5.62
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 .86 1.1 e10 1.6 6.5 21 9.1 5.9 2.9 1.3 .79 e.37
2 .81 1.1 e1.4 1.5 5.8 20 8.6 6.9 2.9 1.2 .73 e.39
3 .71 1.0 e5.0 1.5 5.4 24 8.1 8.0 3.0 1.2 .72 e.40
4 .69 1.1 e1.7 1.4 5.1 19 7.3 5.9 3.0 1.2 .73 e.34
5 .64 1.1 e2.6 1.4 4.5 16 21 5.6 3.0 1.2 .82 e.33
6 .64 1.9 e5.4 1.4 12 15 12 5.2 2.7 1.2 1.2 e.32
7 .63 3.6 e1.8 1.3 312 14 8.9 5.6 2.6 1.2 .75 e.39
8 .63 2.4 e1.5 1.3 76 15 39 4.9 2.7 1.1 .67 e.43
9 .64 .98 e1.4 1.3 265 34 16 4.7 2.8 1.1 .70 e.60
10 .66 .96 e1.2 1.3 64 17 14 4.5 2.6 1.0 .74 e.47
11 .68 e.92 e1.1 1.3 37 15 26 4.2 2.3 1.0 .74 .44
12 .66 e.74 e1.9 1.2 27 14 15 4.4 2.5 .96 .72 .44
13 .68 e.70 e3.4 1.2 24 13 13 4.1 2.7 1.5 .66 .46
14 .70 e.61 e2.8 1.3 22 17 12 3.8 2.6 .98 .63 .48
15 .69 e.58 e2.5 3.7 20 20 12 3.6 2.7 .97 .61 .47
16 .66 e.56 e2.3 4.2 37 15 11 3.5 2.8 .97 .59 .46
17 .64 e.63 e2.1 1.5 119 13 11 4.2 2.7 .97 .60 .52
18 .67 e.54 2.3 12 56 12 10 3.8 2.6 .93 .63 .47
19 .68 e.49 2.3 30 40 13 9.4 3.6 2.5 .87 .66 .47
20 .66 e.54 2.4 36 72 13 9.1 3.7 2.4 .86 .61 .49
21 .61 .92 2.0 7.1 102 12 9.0 3.1 2.6 .84 .57 .54
22 .53 1.7 2.1 5.4 49 12 8.0 2.8 2.6 .83 .53 1.4
23 .56 5.3 2.2 21 40 13 7.1 2.9 2.2 .84 .50 .43
24 4.8 1.4 2.1 8.4 31 16 7.0 2.7 2.5 .88 .53 .39
25 1.0 1.1 2.2 6.4 45 23 6.8 2.4 2.4 .85 .51 .38
26 .89 e1.0 2.2 13 28 16 6.9 2.3 2.2 .82 .46 .33
27 .96 e.98 2.1 8.0 24 15 7.2 2.3 2.1 .84 e.40 .34
28 1.1 e2.0 1.7 6.4 23 14 6.8 2.4 1.7 .83 e.39 .31
29 1.1 e6.1 1.7 5.7 --- 13 7.4 2.3 1.3 .82 e.40 .33
30 1.1 e29 1.7 5.3 --- 14 7.3 2.3 1.3 .75 e.42 .37
31 1.1 --- 1.9 15 --- 14 --- 2.6 --- .78 e.40 ---
TOTAL 27.38 71.05 77.0 208.1 1552.3 502 346.0 124.2 74.9 30.79 19.41 13.56
MEAN .88 2.37 2.48 6.71 55.4 16.2 11.5 4.01 2.50 .99 .63 .45
MAX 4.8 29 10 36 312 34 39 8.0 3.0 1.5 1.2 1.4
MIN .53 .49 1.1 1.2 4.5 12 6.8 2.3 1.3 .75 .39 .31
AC-FT 54 141 153 413 3080 996 686 246 149 61 38 27
e Estimated.
STATISTICS OF MONTHLY MEAN DATA FOR WATER YEARS 1981 - 1999, BY WATER YEAR (WY)
OCT NOV DEC JAN FEB MAR APR MAY JUN JUL AUG SEP
MEAN .88 3.27 6.35 17.4 34.4 17.9 7.71 3.03 1.43 .54 .25 .23
MAX 2.20 16.6 30.1 79.3 194 90.7 42.3 13.0 4.44 2.05 .78 .53
(WY) 1992 1984 1984 1993 1998 1983 1982 1983 1998 1983 1998 1986
MIN .072 .12 .65 .16 .65 .47 .70 .19 .14 .023 .001 .000
(WY) 1989 1993 1990 1991 1989 1990 1990 1991 1990 1989 1988 1988
SUMMARY STATISTICS FOR 1998 CALENDAR YEAR FOR 1999 WATER YEAR WATER YEARS 1981 - 1999
ANNUAL TOTAL 9368.09 3046.69
ANNUAL MEAN 25.7 8.35 7.63
HIGHEST ANNUAL MEAN 25.8 1998
LOWEST ANNUAL MEAN .70 1989
HIGHEST DAILY MEAN 1270 Feb 3 312 Feb 7 1270 Feb 3
1998
LOWEST DAILY MEAN .43 Sep 23 .31 Sep 28 .00 Aug 28
1981
ANNUAL SEVEN-DAY MINIMUM .45 Sep 18 .35 Sep 24 .00 Sep 6
1981
INSTANTANEOUS PEAK FLOW 1260 Feb 7 3890 Feb 3
1998
INSTANTANEOUS PEAK STAGE 8.88 Feb 7 15.48 Feb 3
1998
ANNUAL RUNOFF (AC-FT) 18580 6040 5520
10 PERCENT EXCEEDS 47 18 14
50 PERCENT EXCEEDS 2.9 2.1 .77
90 PERCENT EXCEEDS .59 .53 .04
11180825 SAN LORENZO CREEK ABOVE DON CASTRO RESERVOIR, NEAR CASTRO VALLEY, CA-Continued
WATER-QUALITY RECORDS
PERIOD OF RECORD.-December 1980 to September 1994, October 1997 to current year, (storm season only).
WATER TEMPERATURE: December 1980 to September 1994, October 1997 to current year.
SEDIMENT DATA: December 1980 to September 1994, October 1997 to current year.
PERIOD OF DAILY RECORD.-December 1980 to September 1994, October 1997 to current year.
WATER TEMPERATURE: December 1980 to September 1994, October 1997 to current year.
SUSPENDED-SEDIMENT DISCHARGE: December 1980 to September 1994, October 1997 to current year.
REMARKS.-Sediment samples were collected on most days where water temperature is published. Zero bed-load
discharge observed for flows less than 11.4 ft3/s.
EXTREMES FOR PERIOD OF DAILY RECORD.-
SEDIMENT CONCENTRATION (storm season only): Maximum daily mean, 15,300 mg/L, Feb. 3, 1998; minimum daily mean,
0 mg/L, Feb. 26, 1989.
SEDIMENT LOAD (storm season only): Maximum daily, 80,900 tons, Feb. 3, 1998; minimum daily, 0 ton several days
in most years.
EXTREMES FOR CURRENT YEAR.-
SEDIMENT CONCENTRATION (storm season only): Maximum daily mean, 6,080 mg/L, Feb. 7; minimum daily mean, 12
mg/L, Jan. 17.
SEDIMENT LOAD (storm season only): Maximum daily, 12,000 tons, Feb. 7; minimum daily, 0.02 tons, Nov. 19.
PARTICLE-SIZE DISTRIBUTION OF SUSPENDED SEDIMENT, WATER YEAR OCTOBER 1998 TO SEPTEMBER 1999
DIS- SEDI- SED. SED.
CHARGE, MENT, SUSP. SUSP.
INST. SEDI- DIS- FALL FALL
CUBIC TEMPER- MENT, CHARGE, DIAM. DIAM.
FEET ATURE SUS- SUS- % FINER % FINER
DATE TIME PER WATER PENDED PENDED THAN THAN
SECOND (DEG C) (MG/L) (T/DAY) .002 MM .004 MM
(00061) (00010) (80154) (80155) (70337) (70338)
OCT
07... 1220 .68 11.0 21 .04 -- --
DEC
05... 1355 e2.6 7.5 44 .31 -- --
JAN
20... 1435 16 12.0 227 9.8 -- --
22... 1210 5.5 10.5 34 .50 -- --
31... 0945 22 8.5 2300 137 62 75
FEB
18... 1020 40 10.5 182 20 -- --
18... 1440 84 11.5 1310 297 29 37
MAR
25... 0735 24 11.0 664 43 -- --
31... 1545 9.9 11.0 40 1.1 -- --
APR
11... 1515 22 10.5 630 37 -- --
23... 0820 7.2 12.0 17 .33 -- --
SED. SED. SED. SED. SED. SED. SED.
SUSP. SUSP. SUSP. SUSP. SUSP. SUSP. SUSP.
FALL FALL FALL SIEVE SIEVE SIEVE SIEVE
DIAM. DIAM. DIAM. DIAM. DIAM. DIAM. DIAM.
% FINER % FINER % FINER % FINER % FINER % FINER % FINER
DATE THAN THAN THAN THAN THAN THAN THAN
.008 MM .016 MM .031 MM .062 MM .125 MM .250 MM .500 MM
(70339) (70340) (70341) (70331) (70332) (70333) (70334)
OCT
07... -- -- -- 56 -- -- --
DEC
05... -- -- -- 60 -- -- --
JAN
20... -- -- -- 95 98 100 --
22... -- -- -- 83 -- -- --
31... 87 94 98 99 99 100 --
FEB
18... -- -- -- 86 91 94 100
18... 48 57 71 82 90 98 100
MAR
25... -- -- -- 98 99 100 --
31... -- -- -- 74 93 99 100
APR
11... -- -- -- 96 98 100 --
23... -- -- -- 69 -- -- --
e Estimated.
PARTICLE-SIZE DISTRIBUTION OF BEDLOAD, WATER YEAR OCTOBER 1998 TO SEPTEMBER 1999
TIME HORI- COMPSTD
BAG TETHER ON BED ZONTAL SAMPLES
MESH LINE START- END- FOR WIDTH IN
SAM- SIZE USED IN ING ING BED OF X-SEC
PLING SAMPLER BEDLOAD SAMPLNG TIME TIME LOAD VER- BEDLOAD
DATE TIME METHOD, TYPE SAMPLER (YES=1) (2400 (2400 SAMPLE TICAL MEASMNT
CODES (CODE) (MM) (CODE) HOURS) HOURS (SEC) (FEET) (NUM)
(82398) (84164) (30333) (04117) (82073) (82074) (04120) (04121) (04118)
FEB
18... 1410 1000 1120 .250 0 1405 1415 190 1.0 2
18... 1425 1000 1120 .250 0 1420 1430 190 1.0 2
VER- SAMPLE DIS- DISCH, SEDI- SED. SED.
TICALS NUMBER LOC- CHARGE, BEDLOAD MENT BEDLOAD BEDLOAD
IN OF ATION, INST. AV UNIT DIS- SIEVE SIEVE
COM- SAM- CROSS CUBIC TEMPER- FOR COM CHARGE, DIAM. DIAM.
POSITE PLING SECTION FEET ATURE POSITE BEDLOAD % FINER % FINER
DATE SAMPLE POINTS (FT FM PER WATER SAMPLE (TONS/ THAN THAN
(NUM) (COUNT) L BANK) SECOND (DEG C) T/D/FT DAY) .062 MM .125 MM
(04119) (00063) (00009) (00061) (00010) (04122) (80225) (80226) (80227)
FEB
18... 19 19 .40 87 11.5 .57 10 1 2
18... 19 19 .40 85 11.5 .49 10 1 3
SED. SED. SED. SED. SED. SED. SED. SED. SED.
BEDLOAD BEDLOAD BEDLOAD BEDLOAD BEDLOAD BEDLOAD BEDLOAD BEDLOAD BEDLOAD
SIEVE SIEVE SIEVE SIEVE SIEVE SIEVE SIEVE SIEVE SIEVE
DIAM. DIAM. DIAM. DIAM. DIAM. DIAM. DIAM. DIAM. DIAM.
% FINER % FINER % FINER % FINER % FINER % FINER % FINER % FINER % FINER
DATE THAN THAN THAN THAN THAN THAN THAN THAN THAN
.250 MM .500 MM 1.00 MM 2.00 MM 4.00 MM 8.00 MM 16.0 MM 32.0 MM 64.0 MM
(80228) (80229) (80230) (80231) (80232) (80233) (80234) (80235) (80236)
FEB
18... 18 56 64 68 71 74 75 75 100
18... 22 68 81 87 92 97 100 -- --
TEMPERATURE, WATER (DEG. C), WATER YEAR OCTOBER 1998 TO SEPTEMBER 1999
DAILY INSTANTANEOUS VALUES
DAY OCT NOV DEC JAN FEB MAR APR MAY JUN JUL AUG SEP
1 --- --- --- --- --- --- --- --- --- --- --- ---
2 --- --- --- --- --- --- --- --- --- --- --- ---
3 --- --- --- 6.0 7.0 10.5 11.0 --- --- --- --- ---
4 --- --- --- --- --- --- --- --- --- --- 15.0 ---
5 --- --- 7.5 --- --- --- --- --- --- --- --- ---
6 --- --- --- 5.0 8.5 --- 11.5 --- --- --- --- ---
7 11.0 --- 6.5 --- 11.0 7.5 --- --- --- --- --- ---
8 --- --- --- --- --- --- --- --- --- --- --- ---
9 --- --- 7.0 --- 10.0 --- --- --- --- --- --- ---
10 --- --- --- --- --- 7.0 --- --- --- --- --- ---
11 --- --- --- --- --- 8.5 10.5 --- --- --- --- ---
12 --- --- 6.5 --- --- --- --- --- --- --- --- ---
13 --- --- --- 8.5 --- --- --- --- --- --- --- ---
14 --- --- 9.0 --- 10.0 --- --- --- --- --- --- ---
15 --- --- --- 9.0 --- --- --- --- --- --- --- ---
16 --- --- 9.0 11.5 11.0 --- 13.0 --- --- --- --- ---
17 --- --- --- --- 11.0 10.5 13.0 --- --- --- --- ---
18 --- --- --- 13.0 11.5 --- --- --- --- --- --- ---
19 --- --- 7.5 --- --- 11.0 --- --- --- --- --- ---
20 --- 8.0 6.5 12.0 --- --- 14.5 --- --- --- --- ---
21 --- --- --- 11.5 8.5 11.0 --- --- --- --- --- ---
22 --- --- --- 10.5 --- --- --- --- --- --- --- ---
23 --- --- 2.0 --- --- --- 12.0 --- --- --- --- ---
24 --- --- --- --- --- 11.0 --- --- --- --- --- ---
25 --- --- --- --- 9.5 11.0 --- --- --- --- --- ---
26 --- --- --- --- --- --- --- --- --- --- --- ---
27 --- --- 4.0 6.0 --- --- --- --- --- --- --- ---
28 --- --- --- --- 11.0 --- --- --- 18.5 --- --- ---
29 --- --- 5.5 6.0 --- --- --- --- --- --- --- ---
30 --- --- --- --- --- --- --- --- --- --- --- ---
31 --- --- 8.0 8.5 --- 11.0 --- --- --- --- --- ---
SEDIMENT DISCHARGE, SUSPENDED (TONS/DAY), WATER YEAR OCTOBER 1998 TO SEPTEMBER 1999
MEAN MEAN MEAN
MEAN CONCEN- SEDIMENT MEAN CONCEN- SEDIMENT MEAN CONCEN- SEDIMENT
DISCHARGE TRATION DISCHARGE DISCHARGE TRATION DISCHARGE DISCHARGE TRATION DISCHARGE
DAY (CFS) (MG/L) (TONS/DAY) (CFS) (MG/L) (TONS/DAY) (CFS) (MG/L) (TONS/DAY)
OCTOBER NOVEMBER DECEMBER
1 .86 21 .05 1.1 23 .07 e10 1400 38
2 .81 21 .05 1.1 22 .06 e1.4 100 .38
3 .71 21 .04 1.0 21 .06 e5.0 505 6.82
4 .69 21 .04 1.1 24 .07 e1.7 42 .19
5 .64 20 .04 1.1 31 .09 e2.6 44 .31
6 .64 21 .04 1.9 111 1.1 e5.4 230 3.4
7 .63 21 .04 3.6 262 3.8 e1.8 43 .21
8 .63 21 .04 2.4 169 2.0 e1.5 41 .17
9 .64 20 .04 .98 61 .17 e1.4 40 .15
10 .66 20 .04 .96 66 .19 e1.2 36 .12
11 .68 20 .04 e.92 53 .14 e1.1 31 .09
12 .66 20 .04 e.74 33 .07 e1.9 48 .25
13 .68 19 .04 e.70 30 .06 e3.4 320 2.9
14 .70 19 .04 e.61 26 .04 e2.8 160 1.2
15 .69 19 .04 e.58 21 .03 e2.5 72 .49
16 .66 19 .03 e.56 17 .03 e2.3 56 .35
17 .64 18 .03 e.63 23 .04 e2.1 38 .23
18 .67 18 .03 e.54 22 .03 2.3 33 .20
19 .68 18 .03 e.49 18 .02 2.3 26 .16
20 .66 17 .03 e.54 21 .03 2.4 42 .28
21 .61 17 .03 .92 47 .36 2.0 45 .25
22 .53 17 .03 1.7 141 1.3 2.1 42 .24
23 .56 18 .03 5.3 576 22 2.2 39 .23
24 4.8 354 17 1.4 97 .42 2.1 34 .19
25 1.0 32 .09 1.1 76 .22 2.2 29 .17
26 .89 27 .06 e1.0 84 .25 2.2 24 .14
27 .96 30 .08 e.98 59 .16 2.1 34 .19
28 1.1 33 .10 e2.0 150 .81 1.7 36 .16
29 1.1 30 .09 e6.1 610 10 1.7 33 .15
30 1.1 27 .08 e29 4700 368 1.7 33 .16
31 1.1 24 .07 --- --- --- 1.9 35 .18
TOTAL 27.38 --- 18.43 71.05 --- 411.62 77.0 --- 57.96
JANUARY FEBRUARY MARCH
1 1.6 34 .15 6.5 101 1.8 21 87 4.9
2 1.5 32 .14 5.8 52 .82 20 61 3.3
3 1.5 31 .12 5.4 33 .48 24 431 29
4 1.4 31 .12 5.1 30 .41 19 298 15
5 1.4 30 .11 4.5 28 .34 16 229 10
6 1.4 30 .11 12 128 8.1 15 172 7.0
7 1.3 29 .10 312 6080 12000 14 127 4.8
8 1.3 28 .10 76 746 158 15 140 5.8
9 1.3 27 .09 265 4990 6460 34 365 52
10 1.3 26 .09 64 710 133 17 129 5.8
11 1.3 26 .09 37 338 34 15 142 5.8
12 1.2 25 .08 27 206 15 14 115 4.4
13 1.2 24 .08 24 174 11 13 83 3.0
14 1.3 24 .08 22 125 7.3 17 120 6.8
15 3.7 108 5.2 20 91 4.9 20 229 13
16 4.2 69 1.5 37 343 71 15 157 6.3
17 1.5 12 .05 119 2070 1330 13 133 4.8
18 12 255 15 56 530 107 12 109 3.6
19 30 985 421 40 278 30 13 119 4.5
20 36 898 230 72 1170 509 13 86 3.0
21 7.1 79 1.6 102 1620 544 12 74 2.5
22 5.4 37 .55 49 619 83 12 75 2.5
23 21 236 16 40 400 43 13 86 3.0
24 8.4 80 1.8 31 304 26 16 110 6.3
25 6.4 53 .93 45 843 112 23 600 43
26 13 74 2.8 28 284 22 16 289 12
27 8.0 31 .67 24 114 7.5 15 225 8.8
28 6.4 27 .47 23 70 4.3 14 167 6.2
29 5.7 24 .37 --- --- --- 13 124 4.5
30 5.3 22 .32 --- --- --- 14 89 3.3
31 15 1240 106 --- --- --- 14 42 1.7
TOTAL 208.1 --- 805.72 1552.3 --- 21723.95 502 --- 286.6
e Estimated.
SEDIMENT DISCHARGE, SUSPENDED (TONS/DAY), WATER YEAR OCTOBER 1998 TO SEPTEMBER 1999
MEAN
MEAN CONCEN- SEDIMENT
DISCHARGE TRATION DISCHARGE
DAY (CFS) (MG/L) (TONS/DAY)
APRIL
1 9.1 26 .64
2 8.6 26 .60
3 8.1 26 .56
4 7.3 23 .45
5 21 94 8.9
6 12 32 1.0
7 8.9 23 .56
8 39 420 90
9 16 157 6.8
10 14 138 5.3
11 26 646 61
12 15 291 12
13 13 127 4.4
14 12 90 3.0
15 12 64 2.0
16 11 48 1.5
17 11 42 1.3
18 10 30 .82
19 9.4 24 .61
20 9.1 20 .48
21 9.0 18 .44
22 8.0 18 .38
23 7.1 17 .33
24 7.0 17 .31
25 6.8 16 .30
26 6.9 16 .30
27 7.2 16 .30
28 6.8 15 .28
29 7.4 17 .35
30 7.3 18 .40
31 --- --- ---
TOTAL 346.0 --- 205.31
PERIOD 2783.83 23509.59
SUMMARY OF WATER AND SEDIMENT DISCHARGE, WATER YEAR OCTOBER 1998 TO SEPTEMBER 1999
WATER SUSPENDED BEDLOAD TOTAL
MONTH DISCHARGE SEDIMENT DISCHARGE SEDIMENT
DISCHARGE DISCHARGE
CFS-DAYS TONS TONS TONS
OCTOBER 1998 27.38 18.43 0 18
NOVEMBER .... 71.05 411.62 0 412
DECEMBER .... 77.00 57.96 0 58
JANUARY 1999 208.10 805.72 8 814
FEBRUARY .... 1552.30 21723.95 155 21900
MARCH ....... 502.00 286.60 1 288
APRIL ....... 346.00 205.31 4 209
PERIOD ...... 2783.83 23509.59 168 23699
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