Big Lost River below Mackay Reservoir, ID
River level and flood forecast · Custer County
The river is 2.2 ft below flood stage (4.3 ft).
Forecast to hold near 2.1 ft through Mon, Oct 19, 6 PM.
Flow: 207 cubic feet per second (USGS).
The last 7 days and the forecast
NWS forecast issued Mon, Oct 12, 1:07 PM. Forecasts change as rain falls and as upstream water arrives.
Get flood alerts for this river
An email when the National Weather Service forecasts Big Lost River below Mackay Reservoir to flood, when it floods, and when it's over.
Flood stages
| Flood stage | 4.3 ft |
| Action stage | 3.8 ft |
| Record crest (June 6, 1986) | 6.08 ft |
What floods at each level
From the National Weather Service, highest first.
- 4.3 ftLowland flooding below Mackay Dam through the Darlington Flats. US Highway 93 may be impacted at the curve by Leslie between 3900 North and 4050 North.
- 3.8 ftNear bankfull from Mackay Dam through the Darlington Flats. Water is likely to start to seep in low-lying areas in the Darlington Flats.
Highest crests on record
- 6.08 ft — June 6, 1986
- 5.93 ft — June 17, 1974
- 5.89 ft — June 14, 1965
- 5.79 ft — June 10, 1921
- 5.65 ft — May 26, 1958
Recent crests: 2.78 ft (June 7, 2020) · 4.19 ft (June 17, 2019) · 4.95 ft (May 27, 2018) · 5.09 ft (June 10, 2017) · 3.91 ft (June 9, 2016)
Up and down the river, and nearby
- UpstreamEastern Idaho Reservoirs at Mackay Dam, ID
- DownstreamBig Lost River near Arco, ID
- Big Lost River at Leslie, ID
- Antelope Creek (ID) near Darlington, ID
- Big Lost River at Howell Ranch, ID
- North Fork Big Lost River at Wild Horse, ID
- Little Lost River below Wet Creek (Clyde), ID
- Little Lost River near Howe, ID
Not an official source. River levels, forecasts, flood stages and impacts are from the National Weather Service (MAKI1); flow from the U.S. Geological Survey. Readings are provisional. In a flood, follow your local officials and the NWS at weather.gov.