Mammoth Creek
Today’s report
Mammoth Creek is fishing well today. Flows are running 33.9 cfs and falling. The DWR last stocked rainbow trout (242 fish) on June 23. Overnight's forecast: clear, 34°F.
- flows are dropping — often the best window
- calm, fishable weather
Current conditions · updated 1h ago
Flow as of Oct 16, 7:45 AM MT · USGS 10173450
Stocking
Last stocked Jun 23, 2026 — rainbow trout (242 fish).
| Date | Species | Quantity | Avg length |
|---|---|---|---|
| Jun 23, 2026 | rainbow trout | 242 | 10.54" |
| May 20, 2026 | tiger trout (brown × brook hybrid) | 500 | 10.19" |
| May 18, 2026 | rainbow trout | 260 | 10.12" |
| May 6, 2026 | brown trout | 3,046 | 3.28" |
| Jul 8, 2025 | rainbow trout | 251 | 10.51" |
| Jun 4, 2025 | tiger trout (brown × brook hybrid) | 511 | 9.21" |
| May 28, 2025 | rainbow trout | 252 | 10.21" |
| May 28, 2025 | brown trout | 3,780 | 4.11" |
Best time to fish Mammoth Creek
The DWR has stocked Mammoth Creek 22 times over the last 5 seasons, and 86% of those plants landed in May through July — the freshest fish and the easiest bite usually follow within a week or two of a stocking. Flows typically peak in May (about 150 cfs median) and settle to their lowest in January (about 11 cfs) — the wadeable, clear-water window usually opens once flows drop below the seasonal median, and the 72-hour chart above shows where today sits against it.
Species
Location
Nearby waters (within ~25 mi):
Regulations
From the canal diversion (about three miles upstream from the Mammoth Creek Fish Hatchery), upstream 7.5 miles to the end of Hatch Meadow and the beginning of summer home sites.
- Limit 2 trout between 10 and 15 inches.
- All trout less than 10 inches or over 15 inches must be immediately released.
- Artificial flies and lures only.
Special rules from the 2026 Utah Fishing Guidebook. Statewide daily limits apply to anything not listed. Rules change — always verify in the current guidebook before you fish.