Mammoth Creek (Garfield County) fishing
Mammoth Creek was last stocked on June 23, 2026 with 242 rainbow trout (10.5 in. average), according to the Utah DWR fish stocking report. It is a river or stream in Garfield County, Utah. From 2021 to 2026, DWR stocked 27,049 fish here, the 10th most of 65 stocked waters in Garfield County.
Recent stockings at Mammoth Creek
- June 23, 2026242 rainbow trout, 10.5 in. average
- May 20, 2026500 tiger trout, 10.2 in. average
- May 18, 2026260 rainbow trout, 10.1 in. average
- May 6, 20263,046 brown trout, 3.3 in. average
- July 8, 2025251 rainbow trout, 10.5 in. average
- June 4, 2025511 tiger trout, 9.2 in. average
Newest first, from the Utah DWR stocking report. Full stocking history.
Mammoth Creek facts
- Last stocked
- June 23, 2026 (140 days ago): 242 rainbow trout
- Stockings in 2026
- 4 (4,048 fish): 3,046 brown trout, 502 rainbow trout and 500 tiger trout
- County
- Garfield County
- Stocked since 2021
- rainbow trout, brown trout and tiger trout
- Likely catch (DWR)
- brook trout, brown trout, cutthroat trout and rainbow trout
- Average size stocked
- 5.2 in. (2021 to 2026)
- County rank
- 10th most fish of 65 stocked waters in Garfield County since 2021
- Name in DWR report
- MAMMOTH CR
- Nearest water
- Reed Valley Creek, 1.7 mi
- Rules
- Water-specific rules in the 2026 guidebook
Mammoth Creek stocking report, last 12 months
| June 23, 2026 | Rainbow trout | 242 | 10.5 in. |
| May 20, 2026 | Tiger trout | 500 | 10.2 in. |
| May 18, 2026 | Rainbow trout | 260 | 10.1 in. |
| May 6, 2026 | Brown trout | 3,046 | 3.3 in. |
Source: Utah DWR fish stocking report. Stocking data fetched Nov. 10, 2026; newest record dated Nov. 19, 2026. DWR posts stockings after they happen and does not publish schedules.
Mammoth Creek stocking profile
- First record in the DWR report: May 14, 2002. Since then DWR has logged 145 stockings here in 25 different years, 150,667 fish in all.
- Species stocked 2021 to 2026, by share of fish: brown trout 74% (19,933 fish), rainbow trout 17% (4,487 fish) and tiger trout 10% (2,629 fish).
- Busiest months in the record: June (34% of records) and July (32% of records).
- Stocked fish averaged 5.2 in. from 2021 to 2026 (per-record averages ranged from 2.6 to 11.0 in.). The yearly average was 6.3 in. in 2021 and 5.3 in. in 2025.
- Fish stocked 2021 to 2026: 27,049, the 10th most of 65 stocked waters in Garfield County and 195th of 1,076 statewide.
- Nearest other water with a page: Reed Valley Creek, 1.7 mi away.
- Other water with this name: Mammoth Creek in Iron County, 8 mi away. DWR lists them as separate waters (DWR water ids VIAA780-03 and VIAA780-04).
Computed from Utah DWR stocking records (fish counts and average lengths as DWR reports them). Past stocking is history, not a schedule.
When is Mammoth Creek stocked?
Based on DWR stocking records, 2021 to 2025. Stocked in 5 of those 5 years.
2025 stocking: 4 records, first on May 28, last on July 8.
DWR does not publish stocking schedules. This is past stocking, not a promise. How we read patterns.
Mammoth Creek stocking history by year
| Year | Records | Fish | Avg. length | Species |
|---|---|---|---|---|
| 2026 | 4 | 4,048 | 5.0 in. | Rainbow trout, Tiger trout, Brown trout |
| 2025 | 4 | 4,794 | 5.3 in. | Rainbow trout, Tiger trout, Brown trout |
| 2024 | 4 | 4,204 | 4.9 in. | Rainbow trout, Tiger trout, Brown trout |
| 2023 | 4 | 4,321 | 4.6 in. | Rainbow trout, Tiger trout, Brown trout |
| 2022 | 4 | 4,160 | 4.7 in. | Rainbow trout, Tiger trout, Brown trout |
| 2021 | 3 | 5,522 | 6.3 in. | Rainbow trout, Brown trout |
| 2020 | 5 | 5,794 | 6.6 in. | Rainbow trout, Brown trout |
| 2019 | 5 | 6,645 | 6.4 in. | Rainbow trout, Brown trout |
| 2018 | 5 | 6,687 | 6.3 in. | Rainbow trout, Brown trout |
| 2017 | 1 | 3,064 | 3.6 in. | Brown trout |
| 2016 | 5 | 5,689 | 7.3 in. | Rainbow trout, Brown trout |
| 2015 | 9 | 5,842 | 6.5 in. | Rainbow trout, Brown trout |
| 2014 | 9 | 5,790 | 6.2 in. | Rainbow trout, Brown trout |
| 2013 | 12 | 9,739 | 4.9 in. | Cutthroat trout, Rainbow trout, Brook trout, Brown trout |
| 2012 | 9 | 9,558 | 5.4 in. | Cutthroat trout, Rainbow trout, Brook trout, Brown trout |
| 2011 | 8 | 8,506 | 5.5 in. | Cutthroat trout, Rainbow trout, Brown trout, Brook trout |
| 2010 | 10 | 9,273 | 5.4 in. | Cutthroat trout, Rainbow trout, Brown trout, Brook trout |
| 2009 | 8 | 7,749 | 7.0 in. | Rainbow trout, Brown trout, Brook trout |
| 2008 | 9 | 8,673 | 5.8 in. | Cutthroat trout, Rainbow trout, Brown trout, Brook trout |
| 2007 | 9 | 6,849 | 6.6 in. | Rainbow trout, Brook trout, Brown trout |
| 2006 | 3 | 4,795 | 5.4 in. | Brook trout, Brown trout, Rainbow trout |
| 2005 | 4 | 4,788 | 5.7 in. | Rainbow trout, Brook trout, Brown trout |
| 2004 | 4 | 4,665 | 5.6 in. | Rainbow trout, Brook trout, Brown trout |
| 2003 | 4 | 5,002 | 4.4 in. | Brook trout, Rainbow trout, Brown trout |
| 2002 | 3 | 4,510 | 3.9 in. | Brook trout, Rainbow trout, Brown trout |
All stocking records 2021 to Nov. 10, 2025 (19)
| July 8, 2025 | Rainbow trout | 251 | 10.5 in. |
| June 4, 2025 | Tiger trout | 511 | 9.2 in. |
| May 28, 2025 | Rainbow trout | 252 | 10.2 in. |
| May 28, 2025 | Brown trout | 3,780 | 4.1 in. |
| July 18, 2024 | Rainbow trout | 260 | 9.8 in. |
| June 12, 2024 | Tiger trout | 501 | 9.0 in. |
| May 14, 2024 | Rainbow trout | 258 | 10.5 in. |
| May 14, 2024 | Brown trout | 3,185 | 3.5 in. |
| July 20, 2023 | Rainbow trout | 240 | 9.9 in. |
| June 27, 2023 | Tiger trout | 605 | 10.8 in. |
| April 19, 2023 | Brown trout | 3,212 | 2.6 in. |
| April 19, 2023 | Rainbow trout | 264 | 9.9 in. |
| July 12, 2022 | Rainbow trout | 306 | 10.3 in. |
| June 15, 2022 | Tiger trout | 512 | 8.7 in. |
| June 8, 2022 | Rainbow trout | 252 | 11.0 in. |
| April 19, 2022 | Brown trout | 3,090 | 3.0 in. |
| July 19, 2021 | Rainbow trout | 1,650 | 10.2 in. |
| May 11, 2021 | Rainbow trout | 252 | 10.5 in. |
| May 11, 2021 | Brown trout | 3,620 | 4.2 in. |
Fishing rules
Sections: From the canal diversion about three miles above the Mammoth Creek Fish Hatchery, upstream 7.5 miles to the end of Hatch Meadow where the summer home sites begin.
- Trout limit: 2, each between 10 and 15 inches.
- All trout under 10 inches or over 15 inches must be released right away.
- Artificial flies and lures only.
From the 2026 Utah Fishing Guidebook, in our own words. Rules can change mid-year: check wildlife.utah.gov/guidebooks before fishing. See statewide limits.
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Mammoth Creek questions
When is Mammoth Creek stocked?
DWR does not publish stocking schedules. Past records show Mammoth Creek was stocked in mid to late May (3 of the last 5 years), early to mid June (3 of the last 5 years) and mid July (4 of the last 5 years). The most recent stocking in the DWR report is dated June 23, 2026.
What fish are in Mammoth Creek?
DWR lists brook trout, brown trout, cutthroat trout and rainbow trout as likely catches and mountain whitefish and tiger trout as possible. Since 2021 DWR has stocked rainbow trout, brown trout and tiger trout.
Are there special fishing rules at Mammoth Creek?
Yes. The 2026 Utah Fishing Guidebook lists rules for this water, summarized on this page. Check the guidebook and DWR updates before fishing.
Stocking: Utah DWR fish stocking report, fetched Nov. 10, 2026. Size, program, species and facilities: DWR Fish Utah. Location: Utah DWR, USGS NHD. Rules: 2026 Utah Fishing Guidebook. Page built Nov. 10, 2026. Found an error? Tell us. Verify rules with DWR before fishing.