The Fishers Health Department (FHD) is warning residents to use caution near several local waterways after recent water quality testing returned unsatisfactory E. coli levels at four locations.

The affected sites are:

• White River at the 116th Street Bridge (6100 Wahpihani Dr.)
• Geist Reservoir at the Olio Road Boat Ramp (10999 Olio Rd.)
• Fall Creek at Geist Park (10800 Florida Rd.)
• Fall Creek at Canal Place (14400 Geist Ridge Dr.)

Health officials say the elevated bacteria levels are consistent with what the department typically sees following periods of heavy rainfall — a pattern well-documented in the Upper White River Watershed, where Fishers sits.

Why Rain Drives Up E. Coli Levels

E. coli is a naturally occurring bacteria found in the intestines of warm-blooded animals. While it doesn’t always cause illness on its own, health officials use it as an indicator for other potentially dangerous bacteria and viruses in the water. Waterborne illnesses linked to contaminated water include dysentery, Hepatitis A, and bacterial gastroenteritis.

When it rains heavily, water rushing over roads, rooftops, sidewalks, driveways, and parking lots carries pollutants directly into storm drains — which eventually empty into local streams and reservoirs. In agricultural areas upstream, runoff can wash animal manure from fields into the same waterways. Older or failing septic systems, stormwater outfalls, and wastewater treatment overflows can also contribute to elevated E. coli counts.

“Frequent unsatisfactory levels at Geist Park and White River are a result of our waterways being in the Upper White River Watershed,” the department noted in its public notice. “Our urban and suburban expansion areas are rapidly increasing, making it particularly susceptible to both agricultural and urbanization influences.”

Warmer water temperatures compound the problem. E. coli thrives in heat, meaning summer conditions can accelerate bacterial growth even between rain events.

What the FHD Tests and Where

The FHD monitors 40 creek and open water locations throughout the area, publishing results monthly during spring, summer, and fall for nine key sites. In addition to E. coli, the department tracks water temperature and dissolved oxygen — both critical indicators of aquatic ecosystem health.

The department recently added a new sampling point at Fall Creek at Canal Place, near where the creek empties into Geist Reservoir east of the Olio Road bridge. The addition allows officials to track how water quality changes as Fall Creek flows into the reservoir and moves south, complementing existing test sites at Family Cove and Cambridge Cove.

What Residents Should Know

Residents who swim, fish, or boat in affected areas should use caution until follow-up testing shows bacteria levels have returned to acceptable ranges. The FHD publishes updated results on its website and offers a free email alert service for water quality and environmental notifications.

The department’s environmental testing program also covers mosquito and rodent control, rabies monitoring, well water sampling, pool inspections, and indoor air quality — a broad public health mandate that keeps local waterways among the most closely watched in the region.

For the latest water quality results or to sign up for email alerts, visit the Fishers Health Department website.