USGS Streamgage 11159690
Aptos C near Aptos, CA
Aptos C near Aptos, CA is USGS streamgage 11159690 in California, monitoring river discharge in hydrologic subbasin 18060015. It drains a watershed of about 10 square miles. Discharge records at this site go back to 1971. Typical flow runs near 1.7 cfs in July and 7.1 cfs in April, with the higher of the two arriving in April.
Gauge details
- State
- California
- Drainage area
- 10 sq mi
- Gauge elevation
- 181 ft
- Subbasin (HUC-8)
- 18060015
- Coordinates
- 37.00162, -121.90607
- USGS site number
- 11159690
- Records begin
- 1971-10-01 (55 years)
Typical flow by month
Long-term daily discharge percentiles from the USGS record (up to 54 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 | 1.1 | 4.8 | 100.1 | |
| February | 1.4 | 8.4 | 116.2 | |
| March | 1.6 | 11.2 | 89.1 | |
| April | 1.4 | 7.1 | 52.6 | |
| May | 1 | 3.9 | 16 | |
| June | 0.7 | 2.4 | 7.3 | |
| July | 0.6 | 1.7 | 6.1 | |
| August | 0.5 | 1.3 | 3.7 | |
| September | 0.6 | 1.2 | 3.1 | |
| October | 0.7 | 1.1 | 3.5 | |
| November | 0.8 | 1.9 | 22.6 | |
| December | 0.9 | 2.7 | 32.1 |
All values in cubic feet per second (cfs).
Common questions
- When does Aptos C near Aptos, CA normally run highest?
- March, on the long-term record. The median daily flow that month is about 11.2 cfs, against 1.1 cfs in October, the lowest month. These are historical normals for the date, not a forecast and not today's reading.
- What is a normal flow for Aptos C near Aptos, CA?
- It depends on the month. In January, half of days historically fall near 4.8 cfs, with the middle 80% of days between 1.1 and 100.1 cfs. The month-by-month table on this page gives the full range.
- How long has Aptos C near Aptos, CA been measured?
- Discharge records at USGS site 11159690 begin in 1971, about 55 years, covering roughly 602 days of published daily values. The long record is what makes the monthly percentiles on this page meaningful.
- Where is Aptos C near Aptos, CA?
- The gauge sits at 37.00162, -121.90607, in California, in hydrologic subbasin 18060015, at an elevation of about 181 feet, draining roughly 10 square miles.
- Can I use Aptos C near Aptos, 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.