State issues harmful-algal-bloom advisory for Utah Lake as cyanobacteria intensifies

The Utah Division of Water Quality on Aug. 6 said a harmful algal bloom (HAB) is present across Utah Lake and advised residents to avoid recreational activities that increase the chance of swallowing lake water or exposing children and pets to surface scums. Hannah Water, an environmental scientist with the Division of Water Quality, described the organisms responsible as cyanobacteria and explained when they pose a health risk. Hannah Water said, “Harmful algal blooms are confusing. We call them HABs, harmful algae, blue green algae, and really the most scientifically accurate name is cyanobacteria.” She told the board the organisms naturally occur in every water body but become harmful when concentrations rise from “hundreds of cells per milliliter” to “millions of cells per milliliter,” producing surface scums and, for some species, toxins. The division said blooms tend to form on warm, sunny days in shallow water bodies with elevated nutrient inputs. Water listed the three main drivers at Utah Lake: hot, sunny weather; nutrient pollution such as nitrogen and phosphorus from sources including wastewater and stormwater runoff; and disturbance—most notably carp uprooting aquatic vegetation. “When you have all of these things going on … you go from hundreds of cells per milliliter … to millions of cells per milliliter,” she said. Health effects described by Water range from skin irritation and gastrointestinal symptoms to more serious outcomes tied to cyanobacterial toxins. She noted the Utah Poison Control Center fields reports and cited two recent calls from local incidents involving gastrointestinal illness and skin irritation. The division’s public-facing monitoring dashboard (habs.utah.gov) is updated with weekly sampling results, Water said. The advisory message from the division: avoid swimming and other activities that increase ingestion or aerosol exposure in areas with visible scum; avoid letting dogs and children play in or drink water from patches of scum; choose lower-risk activities such as boating, fishing and walking. “You should not eat any harmful algae,” Water said. The division also uses satellite imagery to track pigment signatures associated with cyanobacteria and said the bloom that began in late June has intensified and spread northward and into the Jordan River in recent weeks. Board members and staff asked technical questions about buoyancy, sampling frequency and control options such as bubble curtains and localized containment. Water said containment techniques (for example, bubble curtains tested in a marina) can slow transport into a river channel but do not stop lake-wide growth when temperature and nutrient conditions favor cyanobacterial multiplication. She described weekly sampling at 8–10 marina and open-water sites and encouraged partner cities to use the division’s outreach materials. The division recommended that residents watch for official advisories, consult habs.utah.gov for sample results, call the Utah Poison Control Center for exposure concerns, and avoid contact with visible algal scums. The board’s communications and outreach staff said they would distribute the division’s graphics and toolkit to member cities.