City officials were quick to post no trespassing signs in the area, warning hikers to stay away from nearby ponds and streams until an investigation was completed.
City staff collected samples from three Hulls Gulch ponds and Hulls Gulch Creek in the Boise foothills, and initial results showed no algae toxins at levels of concern for humans, pets or wildlife.
However, according to a news release from Boise Parks and Recreation on Sept. 1, blue-green algae was found living in the Hulls Gulch ponds. It's blue-green algae that can create toxins capable of causing illness or mortality in humans, pets and wildlife—but the toxins didn't show up on any test results, just the algae. Aquatic life was found to be healthy in the ponds.
Water samples analyzed toxic algae, cyanide and E. coli bacteria in the area. The results showed cyanide levels below detection and E. coli levels ranged from low to moderate. Hulls Gulch Creek doesn't contain any algae species at all.
The Hulls Gulch ponds will remained signed until the blue-green algae levels drop below what the city calls "levels of potential concern."
In the meantime, the city is working with the Idaho Department of Environmental Quality and the Central District Health Department to implement the Draft Idaho Blue-Green Algae Response Plan. That includes evaluating potential algae treatment options and developing a screening process for all city-owned waterbodies.
In other foothills news, the Table Rock Trail No. 15 from the Old Pen Trail to the Table Rock Loop Trail is closed for repairs from 8 a.m. to 6 p.m., Monday through Friday until Friday, Sept. 11. Table Rock will not be accessible via the Table Rock Trail, nor the Old Pen Trailhead during this time.
Table Rock can still be accessed via Tram Trail No. 14 (park at Warm Springs Golf Course) and Table Rock Road.