The Ohio Environmental Protection Agency's plan to protect the streams from runoff pollution from construction sites, roofs and new roads used to call for a 100-foot buffer.
Last year, the state cut it to 50 feet. Now, it's 30.
"It's kind of a balance to be reasonable but also be protective," said Mark Mann, the Ohio EPA's storm-water program manager.
Environmental advocacy groups don't agree. Trent Dougherty of the Ohio Environmental Council said a 30-foot buffer won't protect a 22-mile scenic stretch of the river between the cities of Delaware and Worthington.
"That's way too close to streams, in our eyes, to guarantee protection," Dougherty said. "The Olentangy is already impacted by urban development.