9 USGS Streamgages
Big Lost River flows and levels
Big Lost River is gauged at 9 USGS streamgages in Idaho, each tracked by Rivermatics. It feeds the Dry Channel Big Lost River. Rivermatics issues a daily machine-learned 14-day flow outlook at 7 of them.
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 |
|---|---|---|---|---|---|---|
| Big Lost River at Howell Ranch near Chilly, ID | ID | 440 | — | 145 | 501.5 | 14-day |
| Big Lost River below Mackay Reservoir near Mackay, ID | ID | 801 | — | 123.4 | 607.1 | 14-day |
| Big Lost River near Leslie, ID | ID | 900 | — | 75.3 | 355.5 | 14-day |
| Big Lost River below Moore Diversion near Moore, ID | ID | 1,325 | — | 57.8 | 4.6 | 14-day |
| Big Lost River at Arco at Sunset Road, ID | ID | 1,348 | — | 0 | 0 | 14-day |
| Big Lost River near Arco, ID | ID | 1,410 | — | 19.9 | 11.3 | 14-day |
| Big Lost River Ab Big Lost River Sinks near Howe, ID | ID | — | — | 0 | 0 | 14-day |
| Big Lost River at Lincoln Blvd Bridge near Atomic City | ID | — | — | 0 | 0 | — |
| Big Lost River below Inl Diversion near Arco, ID | ID | — | — | 0 | 0 | — |
Typical flow by month at Big Lost River below Inl Diversion near Arco, ID
The furthest-downstream gauge on this river, so the fullest flow it carries here. Long-term daily discharge percentiles from the USGS record (up to 41 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 | 0 | 33.4 | |
| February | 0 | 0 | 50.2 | |
| March | 0 | 0 | 67.3 | |
| April | 0 | 0 | 120.8 | |
| May | 0 | 0 | 192 | |
| June | 0 | 0 | 375.4 | |
| July | 0 | 0 | 109.9 | |
| August | 0 | 0 | 17.6 | |
| September | 0 | 0 | 60.2 | |
| October | 0 | 0 | 93.1 | |
| November | 0 | 0 | 83.7 | |
| December | 0 | 0 | 46.4 |
All values in cubic feet per second (cfs).
Common questions
- When does the Big Lost River run highest?
- January, on the long-term record at Big Lost River below Inl Diversion near Arco, ID — the furthest-downstream gauge Rivermatics tracks on this river. Median daily flow there is about 0 cfs that month, against 0 cfs in January, the lowest. Upstream gauges peak on their own schedule; the table on this page gives April and July for each.
- How many gauges are on the Big Lost River?
- Rivermatics tracks 9 USGS streamgages on the Big Lost River, across Idaho. 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.
- Is there a flow forecast for the Big Lost River?
- Yes, at 7 of the 9 gauges. Rivermatics trains a machine-learned model — a temporal-fusion transformer — on each basin's observed flows, weather and snowpack, and issues a daily outlook reaching 14 days ahead: a median estimate inside a confidence band, not a single number to bet on. Every forecast is scored against days the model never trained on, and that track record is published on each gauge's live screen.
- Can I use Big Lost 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.