Mantua Reservoir Recreational Monitoring 2021

Report a Bloom

24-Hour DEQ Environment Incidents Line: (801) 536-4123

Call Utah Poison Control Center

Poison Control (800) 222-1222

If you believe you or your pet have been exposed to a harmful algal bloom, call (800) 222-1222.

Update October 7, 2021 (HABs)

Samples taken on 9/29/2021 were returned on October 6th. The sample from along the north shore contained a toxigenic cell density of 2,879,920 cells/mL of Microcystis which is well above the UDWQ/UDOH recommended Warning Advisory threshold of 100,000 cells/mL. DWQ will continue to watch the reservoir closely.


Update September 30, 2021 (HABs)

The Warning Advisory for Harmful Algal Blooms (HABs) at Mantua Reservoir remains in place.

On September 29th, the DWQ HABs monitoring team visited Mantua Reservoir. Harmful algal blooms were observed and cyanotoxin and cell density samples were collected. Results are pending. As UDWQ and UDOH continue to visit and monitor waterbodies, updates will be posted


Update September 24, 2021 (HABs)

The Warning Advisory for Harmful Algal Blooms (HABs) at Mantua Reservoir remains in place.

Samples taken from the reservoir on September 15th contained toxigenic cyanobacteria cell densities at 2,066,080 cells/mL of Microcystis, which is still above the UDWQ/UDOH recommended Warning Advisory threshold of 100,000 cells/mL.

Keep yourself, your family, and your pets safe during a harmful algal bloom.


Update September 23, 2021 (HABs)

The Warning Advisory for Harmful Algal Blooms (HABs) at Mantua Reservoir remains in place.

On September 22nd, the DWQ HABs monitoring team visited Mantua Reservoir. Harmful algal blooms were observed and cyanotoxin and cell density samples were collected. Results are pending. As UDWQ and UDOH continue to visit and monitor waterbodies, updates will be posted.


Update September 14, 2021 (HABs)

The Warning Advisory for Harmful Algal Blooms (HABs) at Mantua Reservoir remains in place.

Samples taken from the reservoir on September 9th contained toxigenic cyanobacteria cell densities at 5,669,615 cells/mL of Microcystis, which is still above the UDWQ/UDOH recommended Warning Advisory threshold of 100,000 cells/mL.

Keep yourself, your family, and your pets safe during a harmful algal bloom.


Update September 10, 2021 (Waterborne Pathogens)

On September 8th, the DWQ waterborne pathogens monitoring team visited Mantua Reservoir. Samples from near the boat ramp did not contain E. coli above recreational thresholds. Routine sampling will continue monthly.


Update August 20, 2021 (HABs)

The Warning Advisory for Harmful Algal Blooms (HABs) at Mantua Reservoir remains in place.

On August 19th, the DWQ HABs monitoring team visited Mantua Reservoir. More cyanotoxin and cell density samples were collected and results are pending. As UDWQ and UDOH continue to visit and monitor waterbodies, updates will be posted.


Update August 17, 2021 (HABs)

The Warning Advisory for Harmful Algal Blooms (HABs) at Mantua Reservoir remains in place.

Samples taken from the reservoir on August 11th contained toxigenic cyanobacteria cell densities at 12,538,299 cells/mL of Dolichospermum, which is still above the UDWQ/UDOH recommended Warning Advisory threshold of 100,000 cells/mL.

Keep yourself, your family, and your pets safe during a harmful algal bloom.


Update August 6, 2021 (HABs)

The Warning Advisory for Harmful Algal Blooms (HABs) at Mantua Reservoir remains in place.

Samples taken from the reservoir on August 4th contained toxigenic cyanobacteria cell densities at 849,588 cells/mL of Dolichospermum, which is still above the UDWQ/UDOH recommended Warning Advisory threshold of 100,000 cells/mL.

Keep yourself, your family, and your pets safe during a harmful algal bloom.


Update August 5, 2021 (HABs/waterborne pathogens)

The Warning Advisory for Harmful Algal Blooms (HABs) at Mantua Reservoir remains in place.

On August 4th, the DWQ HABs monitoring team visited Mantua Reservoir. HABs were observed along the north shore. Cyanotoxin and cell density samples were collected and results are pending. As UDWQ and UDOH continue to visit and monitor waterbodies, updates will be posted.

The DWQ waterborne pathogens monitoring team visited on August 4th. Samples from near the boat ramp did not contain E. coli above recreational thresholds. Routine sampling for waterborne pathogens will continue monthly.


Update July 22, 2021 (HABs)

The Warning Advisory for Harmful Algal Blooms (HABs) at Mantua Reservoir remains in place.

On July 21st, the DWQ HABs monitoring team visited Mantua Reservoir. HABs were observed along the north shore. Cyanotoxin and cell density samples were collected and results are pending. As UDWQ and UDOH continue to visit and monitor waterbodies, updates will be posted.


Update July 12, 2021 (Waterborne Pathogens/HABs)

The Warning Advisory for Harmful Algal Blooms (HABs) at Mantua Reservoir remains in place.

On July 6th, the DWQ waterborne pathogens monitoring team and HABs monitoring team visited Mantua Reservoir. HABs were observed at the northeast boat ramp and along the north shore. Samples from near the boat ramp did not contain E. coli above recreational thresholds. Routine sampling for waterborne pathogens will continue monthly.


Update July 8, 2021 (HABs)

The Bear River Health Department has issued a Warning Advisory for Mantua Reservoir.

Samples taken from the reservoir on July 6th contained toxigenic cyanobacteria cell densities at 1,176,194 cells/mL, which is above the UDWQ/UDOH recommended Warning Advisory threshold of 100,000 cells/mL.

Keep yourself, your family, and your pets safe during a harmful algal bloom.

Mantua Algal Bloom

Mantua Reservoir, July 6, 2021
Click for a larger version.


Update June 11, 2021 (Waterborne Pathogens)

On June 1st, the DWQ waterborne pathogens monitoring team visited Mantua Reservoir. Samples from near the boat ramp did not contain E. coli above recreational thresholds. Routine sampling will continue monthly.


Update June 4, 2021 (HABs)

On June 1st, the DWQ HABs monitoring team visited Mantua Reservoir. The monitoring team did not observe a harmful algal bloom. Cyanotoxin and cell density samples were not collected. As UDWQ and UDOH continue to visit and monitor waterbodies, updates will be posted.