2 USGS Streamgages · New York Slough system
Old River flows and levels
Old River is gauged at 2 USGS streamgages in California, each tracked by Rivermatics. The mainstem runs about 48 miles (78 km) from headwaters to outlet. It drains into the New York Slough system. It drains roughly 371 square miles at its outlet.
Gauges on this river, upstream to downstream
Ordered by drainage area, which is how far down the river each gauge sits. April and July figures are long-term median daily flows for that month from the USGS record — historical normals, not a forecast and not today's reading.
| Gauge | State | Drainage sq mi | Elevation ft | April p50 cfs | July p50 cfs | Forecast |
|---|---|---|---|---|---|---|
| Old River near Byron, CA | CA | — | 0 | — | — | — |
| Old River near Delta Mendota Canal, CA | CA | — | 0 | — | — | — |
Common questions
- How many gauges are on the Old River?
- Rivermatics tracks 2 USGS streamgages on the Old River, across California. Each has its own page with the site's full flow record and monthly normals. The river may carry other gauges that publish neither daily values nor discharge statistics; those are not tracked here.
- What river system is the Old River part of?
- The Old River drains into the New York Slough system — it is a tributary somewhere in that chain, following the flowpath down to its terminal river. Rivermatics builds this from the USGS/geoconnex reference-mainstem network rather than from names.
- Can I use Old River 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 rivers in the New York Slough system
- Nf Stanislaus River 4 gauges
- Tuolumne River 4 gauges
- Cherry C 3 gauges
- Angels C 2 gauges
- Bear River 2 gauges
- Big C 2 gauges
- Cole C 2 gauges
- Merced River 2 gauges