They measure the “total maximum daily load" of pollution that a river can handle and still be safe for swimming or recreation. The tests only have been required and enforced by environmental agencies since the late 1990s, after the EPA was sued by environmental groups. The standards technically have existed since the 1970s, when the Clean Water Act was passed. Now that the tests have been done on the Oklahoma River, the results will be sent to the EPA, which then, with local agencies, will devise a plan to address the issue. Test results Two tests of fecal matter in the North Canadian River were conducted in recent years with similar results. Both took about four months to complete at locations up and downstream from Oklahoma City. One study was conducted by the Association of Central Oklahoma Governments.
