The Fishers Health Department issued a public health advisory Friday, Sept. 25, after recent water testing produced unsatisfactory E. coli results at two locations along Fall Creek.

The advisory identifies Fall Creek at Canal Place, 14400 Geist Ridge Drive, and Fall Creek at Geist Park, 10800 Florida Road.

The department said unsatisfactory results often follow periods of heavy rainfall. Its notice did not provide bacteria counts, sampling dates or a timetable for follow-up testing.

Both locations help the city track water quality as Fall Creek approaches Geist Reservoir. The department identifies Geist Park as a location where the creek enters Fishers and Canal Place as a point where it begins emptying into the reservoir. Sampling at Canal Place allows comparisons with locations farther into Geist, according to the city’s water-testing information.

E. coli testing helps health officials assess whether water has been contaminated by human or animal waste. Most strains of the bacteria are harmless, but some cause gastrointestinal illness. The bacteria also serve as a warning that other disease-causing organisms may be present, according to the Indiana Department of Environmental Management.

An unsatisfactory result does not identify the source of contamination or establish that anyone has become ill. The Fishers notice did not report illnesses associated with either location.

Rain can carry waste from land into creeks and reservoirs. IDEM identifies pet and wildlife waste, agricultural runoff, leaking septic systems and sewer overflows among the possible sources of E. coli contamination. The advisory did not identify a specific source for these results.

Fishers’ testing program covers 40 creek and open-water locations, with results for nine areas published monthly during spring, summer and fall. The city says runoff from both developed areas and agricultural land affects local water quality. Streets, rooftops and parking lots allow rainfall to run into storm drains and waterways, while vegetated ground helps absorb it. Details and links to sampling results are available on the department’s environmental testing page.

For people spending time on the water, IDEM recommends checking posted advisories, avoiding swallowing surface water while boating, kayaking, canoeing or fishing, washing hands before eating and showering after water contact. Residents can also help reduce contamination by picking up pet waste and having septic systems regularly checked and emptied.

The notice names the two Fall Creek sampling locations and does not announce a park closure. It also does not address household drinking-water quality.

Residents can find water-testing information and sign up for environmental email alerts through the Fishers Health Department.