Chicago River users now have a new way to check the quality of the water

Rowers, kayakers and other users of the Chicago River can now get a real-time look at a measure of water quality thanks to three sensors installed in the river’s three main branches to continuously estimate the amount of bacteria in the water from human and other warm-blooded animals’ waste.

Current, a Chicago advocacy organization for cleaner water, planned to begin making the real-time results available to the public last year. But the coronavirus pandemic delayed that until Thursday, when a website updated with data taken every 15 minutes went online.

Chicago’s development as a city in the 19th century owes much to the river — actually a system of rivers and manmade canals that provided a path between the Great Lakes and the Mississippi River system. The meatpacking and lumber industries used it for shipping. But the waterway became a dumping ground for industries and for sewage from homes and businesses.

Quality of the 156-mile river system has improved in recent years, helped by multibillion-dollar construction of reservoirs and underground tunnels. But when rain overwhelms the sewers, sewage and stormwater still get diverted to the river.

Fecal coliform isn’t dangerous itself, but the bacteria’s presence in the water is a warning that illness-causing pathogens probably are there, too.

Results from traditional testing — based on water sampling from the river — are available through government regulators. But those are collected only intermittently. Users also can check for alerts of any recent sewage diversion.

The optical sensors offer more immediate information to anyone wanting to go out on the water on a given day, says Alaina Harkness, Current’s executive director.

They collect data about the murkiness and temperature of the water and light emitted by tryptophan — an amino acid from microorganisms linked to fecal coliform. That allows for an estimate of the level of bacteria, according to Harkness.

She says it’s enough for, say, a kayaker, to decide to use the river’s main branch instead of the south or north branch if the sensors estimate a level of bacteria above the state standard for safe recreational use.

Trish Brubaker, executive director of the Lincoln Park Boat Club, says she can use that information when planning workouts for rowing clubs — especially for single sculls, which are more apt to tip over.

Heng Zhang, assistant director of monitoring and research for the Metropolitan Water Reclamation District of Greater Chicago, says: “The more information people have, the better. But just understand the information is just an indicator, and it’s not 100%.”