Matt Warner Reservoir is located on Diamond Mountain, north of Vernal in Uintah County. DEQ’s recreational water quality monitoring checks for two health concerns: Harmful Algal Blooms (HABs) and Waterborne Pathogens (E. coli). Find the most recent monitoring information below.
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Updates:
December 1, 2025: Recreational water quality monitoring update
Recreational water quality monitoring has ended for the season. Monitoring will resume in June or July 2026. Harmful algal blooms can occur year-round, so know what to look for and always check before recreating.
October 10, 2025: Harmful algal bloom (HAB) monitoring update
BE CAREFUL: A harmful algal bloom is present at Matt Warner Reservoir. Algae in the water may be producing dangerous toxins that can make humans and animals sick.
TriCounty Health Department has issued a WARNING ADVISORY.
If you visit the Matt Warner Reservoir:
- Do not swim or water ski
- Avoid areas of algae when boating
- Clean fish well and discard guts
- Keep animals away
- Don’t drink the water
- Know how to recognize a harmful algal bloom
July 23, 2025: Harmful algal bloom (HAB) monitoring update
BE CAREFUL: A harmful algal bloom is present at Matt Warner Reservoir. Algae in the water may be producing dangerous toxins that can make humans and animals sick.
TriCounty Health Department has issued a WARNING ADVISORY.
If you visit the Matt Warner Reservoir:
- Do not swim or water ski
- Avoid areas of algae when boating
- Clean fish well and discard guts
- Keep animals away
- Don’t drink the water
- Know how to recognize a harmful algal bloom