History
1800s
Stormwater runoff in the City of Cincinnati was first managed to eliminate local ponding and flooding. While Cincinnati has many creeks and channels to convey stormwater to the Ohio River, the City’s early development required stormwater ditch and pipe improvements to transport stormwater to the creeks.
Starting in 1828, a storm sewer system was constructed to collect stormwater runoff during rainfall events and convey this flow to the nearest natural water course for discharging.
During the later part of the century, Cincinnati began to convert these storm sewers to combined sewers, resulting in a system that could carry wastewater in dry weather to creeks and rivers and also carry stormwater in wet weather.
1897 to 1940s
Cincinnati expanded the combined sewer system to provide access to wastewater sewers for all residents of the City.
During this period, interceptor sewers also began to be constructed. An interceptor sewer connects to combined sewers at locations called regulators. At these regulators, wastewater generated in dry weather is diverted to the interceptor sewer which conveys the wastewater to a treatment plant.
1940s
Cincinnati, along with many other communities, realized the importance of constructing separate sanitary sewers and storm sewers to more effectively manage wastewater and storm water.
If stormwater is collected separately, the volume of wastewater to be conveyed in an interceptor sewer for treatment is greatly reduced.
Separate storm sewers that discharge to local streams reduce pollution of the streams because they do not have mixed wastewater.
1968
The Metropolitan Sewer District (MSD) of Greater Cincinnati was formed to manage the collection and treatment of wastewater in most of Hamilton County. With this formation, sewer maintenance transferred from the City’s Highway Maintenance Division to MSD.
City storm sewer design responsibilities remained under the direction of the City Engineering Division.
1976
Responsibility for operation and maintenance of the Cincinnati storm sewer system (including ditches, inlets, pipes and other conveyance facilities) was returned to the City’s Highway Maintenance Division to allow MSD to concentrate on wastewater-related issues.
1979
A city-wide Storm Drainage Study was conducted for the City of Cincinnati to consider approaches for better planning and maintenance of the existing storm sewer system.
The purpose of the study was to identify problems in the storm sewer system and make recommendations for their correction.
The study concluded that many of the City's drainage problems were the result of unimproved streets lacking proper storm drainage facilities and that many of the problems could be corrected through regularly scheduled maintenance of the existing system.
1984
Cincinnati City Council created the Division of Stormwater Management Utility (SMU) within the Cincinnati Department of Public Works.
The agency was charged with correcting chronic flooding problems, designing new drainage facilities, and maintaining the existing storm sewer and storm inlet system to assure their proper operation during rain events.
Cincinnati's SMU was among the first stormwater utilities created in Ohio.
1995
SMU was transferred from the Department of Public Works to the Department of Sewers (MSD). The transfer was done to eliminate duplicate services and to improve efficiencies of both agencies.
2016
SMU was transferred from MSD to Greater Cincinnati Water Works.
Today
SMU administers a comprehensive stormwater management program that addresses stormwater drainage control to ensure a fully integrated approach to resolving existing drainage problems and meet future needs.
Only separate sanitary and separate storm sewers are allowed to be built today.
Because much of the City’s system was built before 1940, it continues to be comprised primarily of combined sewers with small areas of separate sanitary and storm sewers.
SMU is also the lead agency in implementing the City's NPDES/MS4 program. This EPA mandate requires cities over 100,000 people in population to monitor and reduce pollutants from industrial, wastewater, and municipal processes into creeks, streams, lakes and rivers.