Michigan Report Outlines Progress on CSO, SSO Control
Michigan's Department of Environmental Quality (DEQ) has released its "2007 Combined Sewer Overflow & Sanitary Sewer Overflow Annual Report," which outlines the latest information along with a special feature about how the state became a national leader in combined sewer overflow (CSO) control.
CSOs are overflows from older sewer systems designed to carry both domestic and stormwater loads, while sanitary sewer overflows (SSOs) are discharges of raw or inadequately treated sewage from municipal separate sanitary sewer systems, which are designed to carry domestic sanitary sewage but not stormwater. Discharges of untreated sewage can cause serious detriment to area water quality and often pose significant health risks to the public. Through extensive state support and a strong commitment from communities across Michigan, the state has made steady progress in eliminating discharges of SSOs and untreated CSOs.
In 1988, more than 600 untreated outfalls poured billions of gallons of harmful wastewater into local waters. Now, more than 75 percent of those untreated CSO outfalls have been eliminated by either sewer separation or by providing retention and treatment prior to discharge.
Efforts are under way to address the remaining untreated CSO outfalls.
"These improvements mark continued progress toward eliminating threats to our waters and the health of our families from the discharge of untreated sewage," said DEQ Director Steven E. Chester. "We must continue to make the necessary financial and resource investments in Michigan's future until all untreated sewer overflows are eliminated."
In 1989, the combined efforts of governmental agencies at the local, state, and federal levels created a State Revolving Fund that has tendered more than $2.8 billion in low-interest loans to communities for the necessary infrastructure improvements, including CSO and SSO correction projects.
Over the next 10 years, continued construction and implementation of ongoing CSO control efforts is expected to cost an estimated $2.875 billion.
The report is available at