Rockport Reservoir Algal Bloom Monitoring 2018

Update June 27, 2018

Toxin strip testing performed by the Division of Water Quality (DWQ) near the main boat launch at Rockport State Marina on June 20, 2018, showed microcystin levels exceeding the recommended recreational health-based thresholds for microcystins. Follow-up testing by the Utah Public Health Lab (UPHL) and Utah Department of Agriculture and Food (UDAF) lab, however, showed non-detect for microcystins. While rare, false positives do occur occasionally, which is why DWQ sends samples to state labs to confirm toxin strip-test results.

DWQ collected another sample at the same location on June 21, 2018, for cell-count concentration testing. The cell count density for the June 21, 2018, sample was 1624 cells per milliliter (cells/ml), well below the recommended recreational health-based threshold. The primary cyanobacteria present in the sample was Gloeotrichia, which can be toxic in dense concentrations but an uncommon cause of large harmful algal blooms. Dolichospermum or Microcystis, cyanobacteria genera often responsible for large blooms and cyanotoxins, were not found in the sample.

DWQ visited the key access areas at Rockport State Park on June 26, 2018. Visual inspections of the area did not indicate cyanobacteria accumulating. Toxin strip tests conducted on samples from the main boat launch came back as non-detect for both microcystin and anatoxin-a. DWQ will send these samples to both state labs for confirmation of toxin-test strip results and to PhycoTech for cell counts.


Update June 21, 2018

A Division of Water Quality (DWQ) sampling crew observed a harmful algal bloom while conducting routine E. coli monitoring at Rockport Reservoir on June 20, 2018. The bloom was observed along shorelines at the western and eastern and seemed to be more concentrated near the lake inflow. Toxin test-strip results for the sample collected at the Rockport State Park Marina near the main boat launch exceeded the recommended health-based threshold for microcystin.

DWQ scientists could not determine if the bloom extended over the open water of the lake. The bloom, which did not appear visually to be excessive, was composed of small, olive-green spheres suspended in the water column.

Follow-up sampling is scheduled for early next week.

Toxins

DWQ collected five samples at four locations around the reservoir, collecting both an integrated sample and surface sample at one locations. A sample collected from the main boat launch near the marina came back at approximately 7.5 micrograms per liter (ยต/L) for microcystins. All other samples were non-detect for microcystins, and all samples were non-detect for anatoxin-A.

The sample taken at the marina has been sent to the Utah State Public Health Lab and Utah Department of Agriculture of Food (UDAF) for confirmation toxin testing. Samples will also be sent to the lab for cell-count concentrations and taxa identification.

Summit County Health Department Recommendations

Visitors are encouraged to pay attention to signs and to avoid swimming and boating in areas of scum. Pet owners should prevent pets from drinking or swimming near blooms or areas of scum. While these blooms are localized and do not compromise drinking water, recreationists should take precautions when visiting Rockport Reservoir.

Anglers can still fish in waters where a bloom is occurring. They are encouraged to clean the fish and wash their hands with clean water. Since toxins concentrate mostly in a fish’s organs (fatty tissue and skin) discard these items and eat only the fillets.

The Summit County Health Department is working closely with the Division of State Parks and Recreation, Department of Environmental Quality, Department of Natural Resources, Park City Water, Mountain Regional Water, and Weber Basin Water Conservancy to monitor the algal bloom. All agencies are committed to the safety and well-being of park visitors and the environment. Rockport Reservoir remains open and primarily safe for recreation as monitoring and further testing is conducted.