The Department of Environmental Quality adopted Okla. Admin. Code §252.621, Non-Industrial Flow-Through and Public Water Supply Lagoons Including Land Application. Changes reduce the maximum slope of a wastewater land application site from 10% to no more than 5%. The rule takes effect July 1, 2011. http://www.oar.state.ok.us/register/Volume-28_Issue-19.htm#a281367.