USGS Streamgage 11181008
Castro Valley C A Hayward, CA
Castro Valley C A Hayward, CA is USGS streamgage 11181008 in California, monitoring river discharge in hydrologic subbasin 18050004. It drains a watershed of about 6 square miles. Discharge records at this site go back to 1971. Typical flow runs near 0.4 cfs in July and 0.9 cfs in April, with the higher of the two arriving in April.
Gauge details
- State
- California
- Drainage area
- 6 sq mi
- Gauge elevation
- 105 ft
- Subbasin (HUC-8)
- 18050004
- Coordinates
- 37.67993, -122.08052
- USGS site number
- 11181008
- Records begin
- 1971-10-01 (55 years)
Typical flow by month
Long-term daily discharge percentiles from the USGS record (up to 55 years of data), averaged within each month. These describe the historical normal range — they are not a forecast and not today's reading.
| Month | Low p10 | Typical p50 | High p90 | Range |
|---|---|---|---|---|
| January | 0.3 | 1.1 | 25.2 | |
| February | 0.4 | 1.5 | 30.8 | |
| March | 0.5 | 1.5 | 19.8 | |
| April | 0.5 | 0.9 | 7.3 | |
| May | 0.4 | 0.6 | 1.7 | |
| June | 0.3 | 0.4 | 0.8 | |
| July | 0.2 | 0.4 | 0.6 | |
| August | 0.2 | 0.3 | 0.5 | |
| September | 0.1 | 0.3 | 0.6 | |
| October | 0.1 | 0.3 | 2.4 | |
| November | 0.2 | 0.4 | 11 | |
| December | 0.2 | 0.8 | 19.9 |
All values in cubic feet per second (cfs).
Common questions
- When does Castro Valley C A Hayward, CA normally run highest?
- February, on the long-term record. The median daily flow that month is about 1.5 cfs, against 0.3 cfs in August, the lowest month. These are historical normals for the date, not a forecast and not today's reading.
- What is a normal flow for Castro Valley C A Hayward, CA?
- It depends on the month. In January, half of days historically fall near 1.1 cfs, with the middle 80% of days between 0.3 and 25.2 cfs. The month-by-month table on this page gives the full range.
- How long has Castro Valley C A Hayward, CA been measured?
- Discharge records at USGS site 11181008 begin in 1971, about 55 years, covering roughly 9,126 days of published daily values. The long record is what makes the monthly percentiles on this page meaningful.
- Where is Castro Valley C A Hayward, CA?
- The gauge sits at 37.67993, -122.08052, in California, in hydrologic subbasin 18050004, at an elevation of about 105 feet, draining roughly 6 square miles.
- Can I use Castro Valley C A Hayward, CA data for flood or safety decisions?
- No. Rivermatics provides estimates, not guarantees, and the readings and forecasts here may be delayed, inaccurate, or wrong. Do not use them for navigation or for any safety, rescue, or emergency decision. Check the National Weather Service and USGS directly, and use your own judgment.
Other gauges in this subbasin
- San Lorenzo C A San Lorenzo, CA
- Coyote C near Alviso, CA
- San Antonio C A Indian Creek Road near Sunol, CA
- San Mateo C Ab Junction Box A Dam1 near Hillsborough
- San Mateo C below Junction Box A Dam1 near Hillsborough
- San Mateo C below Lo Crystal Sp Reservoir near San Mateo, CA
- Alameda C Ab Diversion Dam near Sunol, CA
- Alameda C below Diversion Dam near Sunol, CA