Check first
Harmful algae mats may be present
- Do not touch or eat algae mats
- Keep dogs and young children away from mats
- Wading and paddling are ok
Sand Hollow Reservoir is located approximately 9 miles west of Hurricane in Washington 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
October 28, 2025: Harmful algae mats monitoring update
CHECK FIRST: Our monitoring team observed a small amount of harmful algae mats at Sand Hollow Reservoir. Direct contact with or ingestion of mats can make humans and animals sick. Avoid mats while you recreate.
- Do not touch or eat any algae mats
- Keep children away from any algae mats
- Keep animals away from any algae mats
- Wading, fishing, and paddling are OK
- Know how to recognize a harmful algae mats
October 8, 2025: Harmful algae mats monitoring update
BE CAREFUL: Harmful algae mats are present at Sand Hollow Reservoir. Direct contact with or ingestion of mats can make humans sick and may be lethal for dogs.
Sand Hollow Reservoir is under a WARNING ADVISORY.
If you visit the reservoir:
- Keep dogs and young children away from the water
- Do not touch or eat any algae mats
- Don’t filter drinking water here
- Wading, paddling, and fishing are OK
- Know how to recognize a harmful algae mats
September 8, 2025: Harmful algae mats monitoring update
BE CAREFUL: Harmful algae mats are present at Sand Hollow Reservoir. Direct contact with or ingestion of mats can make humans sick and may be lethal for dogs.
Sand Hollow Reservoir is now under a WARNING ADVISORY.
If you visit the reservoir:
- Keep dogs and young children away from the water
- Do not touch or eat any algae mats
- Don’t filter drinking water here
- Wading, paddling, and fishing are OK
- Know how to recognize a harmful algae mats
August 11, 2025: Harmful algae mats monitoring update
CHECK FIRST: Harmful algae mats may be present at Sand Hollow Reservoir. Direct contact with or ingestion of mats can make humans and animals sick. Avoid mats while you recreate.
- Do not touch or eat any algae mats
- Keep children away from any algae mats
- Keep animals away from any algae mats
- Wading, fishing, and paddling are OK
- Know how to recognize a harmful algae mat
GOOD NEWS: E. coli counts were measured below recreational thresholds. Sampling suggests that the water is safe from harmful bacteria and viruses.
Site sampled: Sand Hollow State Park, at boat ramp and at the day-use beach
August 7, 2025: Harmful algae mats monitoring update
CHECK FIRST: Harmful algae mats may be present at Sand Hollow Reservoir. Direct contact with or ingestion of mats can make humans and animals sick. Avoid mats while you recreate.
- Do not touch or eat any algae mats
- Keep children away from any algae mats
- Keep animals away from any algae mats
- Wading, fishing, and paddling are OK
- Know how to recognize a harmful algae mat
July 15, 2025: Waterborne pathogen (E. coli) monitoring update
GOOD NEWS: E. coli counts were measured below recreational thresholds. Sampling suggests that the water is safe from harmful bacteria and viruses.
Site sampled: Sand Hollow State Park, at boat ramp and at the day-use beach
June 2, 2025: Waterborne pathogen (E. coli) monitoring update
GOOD NEWS: E. coli counts were measured below recreational thresholds. Sampling suggests that the water is safe from harmful bacteria and viruses.
Site sampled: Sand Hollow State Park, at boat ramp and at the day-use beach
May 5, 2025: Waterborne pathogen (E. coli) monitoring update
GOOD NEWS: E. coli counts were measured below recreational thresholds. Sampling suggests that the water is safe from harmful bacteria and viruses.
Site sampled: Sand Hollow State Park, south of the boat ramp and at the day-use beach.