11181008 CASTRO VALLEY CREEK AT HAYWARD, CA

LOCATION.-Lat 37°40'48", long 122°04'46", in San Lorenzo (Castro) Grant, Alameda County, Hydrologic Unit 18050004, on left bank 500 ft east of Hayward 
City Hall, 700 ft upstream from mouth, and 700 ft downstream from small left-bank tributary. 
DRAINAGE AREA.-5.51 mi2. 
PERIOD OF RECORD.-October 1971 to current year (seasonal records only, water years 1975-77). 
GAGE.-Water-stage recorder and crest-stage gage. Elevation of gage is 100 ft above sea level, from topographic map. 
REMARKS.-Records good except for estimated daily discharges, which are fair. No regulation or diversion upstream from station. 
EXTREMES FOR PERIOD OF RECORD.-Maximum discharge, 1,550 ft3/s, Feb. 2, 1998, gage height, 9.12 ft, from rating curve extended above 61 
ft3/s on basis of slope-area measurement at gage height 3.92 ft and step-backwater computation to gage height 10.40 ft; no flow at times. 
EXTREMES FOR CURRENT YEAR.-Peak discharges greater than base discharge of 500 ft3/s, or maximum: 
  			Discharge	Gage height			Discharge	Gage height
  	Date	Time	(ft3/s)	(ft)	Date	Time	(ft3/s)	(ft)
  	Nov. 26	0825	969	7.21	Jan. 18	1350	1,160	7.89
  	Dec. 7	1135	568	5.56	Feb. 2	2400	1,550	9.12
  	Jan. 4	0110	570	5.57	Feb. 21	1120	663	5.99
  	Jan. 12	1310	1,040	7.48

                  DISCHARGE, CUBIC FEET PER SECOND, WATER YEAR OCTOBER 1997 TO SEPTEMBER 1998

                                               DAILY MEAN VALUES
 
DAY       OCT      NOV      DEC      JAN      FEB      MAR      APR      MAY      JUN      JUL      AUG      SEP
 
  1       .18      .29     2.1       .58     17        4.3      3.4    e1.0      1.3       .53      .40      .32
  2       .63      .28     1.4     22       243        3.9      4.5     e.98     1.2       .54      .39      .30
  3       .12      .28     1.2     12       226        3.4     30       e.90     1.1       .55      .41      .30
  4       .14      .28      .94    54        44        3.0     11       e.85     1.1       .53      .42      .27
  5       .15      .26     3.8      2.9      23       12        4.4     e.97     1.0       .51      .38     e.27
 
  6       .14      .26     1.2      3.7     110        4.2      6.1    e1.2      1.1       .50      .38     e.27
  7       .13      .28   108        3.9      86        7.2      3.7    e1.1      2.5       .53      .39     e.27
  8       .11      .30    32        1.6      46        3.6      2.7    e1.0      1.6       .52      .55     e.26
  9     19         .28     3.6      8.9      15        2.7      2.5     e.98      .93      .51      .36     e.26
 10       .93    17        1.8     36        11        2.3      2.2     e.91      .92      .52      .38      .26
 
 11       .31     2.0      1.3     93       e21        2.3      2.1    e1.1       .89      .51      .39      .25
 12       .31      .43     1.1    212       e31        4.3     13      e3.0       .85      .48      .39      .25
 13       .35     1.5       .98    17       e16       57       59      e2.4       .77      .50      .40      .24
 14       .33     2.7     29       19       e69        6.1      4.4     1.4       .80      .45      .35      .24
 15       .31    22        2.5     83       e22        4.1      2.9     1.2       .84      .49      .35      .24
 
 16       .32     5.5      1.6     12       e33        3.8      2.3     1.1       .79      .50      .37      .25
 17       .33      .60     1.4      9.6       9.6      3.0      2.1     1.1       .74      .45      .35      .27
 18       .31     2.5      1.2    164         7.2      2.6      2.0     1.0       .69      .47      .34      .24
 19       .31     6.4       .98    35        50        2.3      1.9      .98      .70      .46      .36      .26
 20       .34      .61      .87     7.2      11        2.2      1.7      .92      .68      .44      .35      .24
 
 21       .32      .74      .80     4.8      98        3.3      2.1      .92      .66      .42      .44      .24
 22       .31      .92      .89     9.4      17        2.6      1.6      .89      .65      .42      .41      .23
 23       .32      .77      .72     3.0      35       46        1.8      .90      .69      .43      .34      .23
 24       .30    16         .68     2.5      11       13        1.5      .90     e.73      .42      .37      .24
 25       .29    31         .67     2.2       8.9     19        1.2      .91     e.79      .43      .34      .25
 
 26       .30   164         .62     3.7       6.7      4.8      1.2     1.6      e.71      .42      .50      .31
 27       .28    17         .62     2.5       5.6      8.3      1.2     7.7       .55      .42      .33      .27
 28       .26     1.9       .62     1.8       4.8      6.6      1.1    38         .53      .40      .32      .27
 29       .26    14         .66    69         ---      3.2     e1.1     7.6       .55      .42      .33      .26
 30       .32    28         .60     5.2       ---      2.6     e1.0     2.0       .51      .42      .35      .26
 31       .28      ---      .56     7.3       ---     13        ---     1.5       ---      .40      .36      ---
 
TOTAL   27.99   338.08   204.41   908.78   1277.8    256.7    175.7    87.01    26.87    14.59    11.80     7.82
MEAN      .90     11.3     6.59     29.3     45.6     8.28     5.86     2.81      .90      .47      .38      .26
MAX        19      164      108      212      243       57       59       38      2.5      .55      .55      .32
MIN       .11      .26      .56      .58      4.8      2.2      1.0      .85      .51      .40      .32      .23
AC-FT      56      671      405     1800     2530      509      349      173       53       29       23       16
 
    e  Estimated.


STATISTICS OF MONTHLY MEAN DATA FOR WATER YEARS 1972 - 1998, BY WATER YEAR (WY)                                 
 
          OCT      NOV      DEC      JAN      FEB      MAR      APR      MAY      JUN      JUL      AUG      SEP
MEAN     1.58     4.87     5.49     10.1     10.4     7.60     2.81     1.14      .58      .38      .38      .49
MAX      4.97     19.0     14.2     29.3     45.6     34.6     12.3     3.23     1.55     1.15     1.50     1.62
(WY)     1976     1974     1997     1998     1998     1983     1974     1990     1995     1974     1983     1983
MIN       .15      .24      .24      .39     1.06      .60      .20      .30      .28      .17      .14      .12
(WY)     1978     1993     1990     1991     1977     1988     1977     1992     1980     1991     1980     1980
 
SUMMARY STATISTICS           FOR 1997 CALENDAR YEAR        FOR 1998 WATER YEAR           WATER YEARS 1972 - 1998
 
ANNUAL TOTAL                        1513.13                    3337.55                                          
ANNUAL MEAN                            4.15                       9.14                       4.02               
HIGHEST ANNUAL MEAN                                                                          9.14           1998
LOWEST ANNUAL MEAN                                                                           1.51           1972
  HIGHEST DAILY MEAN                   164     Nov 26             243     Feb  2             322       Jan  4 1982
  LOWEST DAILY MEAN                       .11  Oct  8                .11  Oct  8                .00    Oct 11 1977
  ANNUAL SEVEN-DAY MINIMUM                .18  Sep 13                .20  Oct  2                .00    Oct 11 1977
  INSTANTANEOUS PEAK FLOW                                        1550     Feb  2            1550       Feb  2 1998
  INSTANTANEOUS PEAK STAGE                                          9.12  Feb  2               9.12    Feb  2 1998
ANNUAL RUNOFF (AC-FT)               3000                       6620                       2910                  
10 PERCENT EXCEEDS                     4.9                       20                          6.8                
50 PERCENT EXCEEDS                      .41                        .97                        .48               
90 PERCENT EXCEEDS                      .22                        .27                        .18