Newcastle Reservoir is located southeast of Newcastle in Iron 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
November 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.
June 6, 2025: Harmful algal bloom (HAB) monitoring update
GOOD NEWS: Our monitoring team visited and did not see any visible signs of a harmful algal bloom. There are large amounts of harmless filamentous green algae present. Learn more about how to tell the difference.
June 6, 2025: Harmful algal bloom (HAB) monitoring update
BE CAREFUL: Our monitoring team received reports of a harmful algal bloom at Newcastle Reservoir. There could be algae in the water producing dangerous toxins. Check back here for updates.
In the meantime we recommend:
- Do not swim or water ski in areas of algae
- 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