State regulation of streams that flow temporarily after rainfall would be restricted under proposed Ohio legislation, months in the works. Construction companies, the mining industry and other business groups say removing so-called ephemeral streams from regulation would make Ohio’s practice consistent with federal law. The EPA says about 36,500 miles of the state’s 115,200 miles of primary headwater streams are ephemeral streams. Environmental groups largely oppose the legislation, saying the streams play an important role in maintaining water quality.