On April 26, 2017, Region 10 filed an expedited settlement agreement which both initiated and concluded an administrative action against the City of Walla Walla Mill Creek Water Treatment Plant in Walla Walla, Washington for violations of CAA ? 112(r) Risk Management Program requirements. Respondent failed to comply with several risk management program requirements that apply to its use of chlorine. The municipality agreed to pay a penalty of $3,060.