A bill that would give some slack to Indiana cities with combined sewers passed the state Senate on Thursday. These are systems where sewage, industrial waste and stormwater are collected together and sent to a treatment plant.

During heavy rains, combined sewers can’t handle all that excess dirty water — so some of it gets sent straight into nearby rivers and streams through what’s called a combined sewer overflow or CSO. More than 100 cities in the state have them.

Senate Bill 449 would make it so no water samples could get taken from cities’ CSOs during or after these events. That means the state couldn’t slap them with a violation — though it’s possible the federal government still could.

READ MORE: Combined sewers put too much sewage into waterways. Bill would help cities avoid violations

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Cities with CSOs would still have to comply with their long-term pollution control plans.

The Indiana Department of Environmental Management said it’s sympathetic to cities, but questions how it will ensure they comply with the rules if it can’t test their overflows.

The bill now moves to the House for consideration.

Rebecca is our energy and environment reporter. Contact her at rthiele@iu.edu or follow her on Twitter at @beckythiele.