Milestones

The goal of Save the Rain is to keep Onondaga Lake clean. The ACJ (legal document) mandates that the County:

  • Work to ensure that Onondaga Lake and its tributaries meet water quality standards and,
  • Capture a certain percentage of combined sewage flow each year

Combined sewage includes both sewer and stormwater flows. This page will explain the work that the County has done to achieve and surpass the mandated combined sewage percent capture milestones.

Are you familiar with the term combined sewage or Combined Sewer Overflows (CSOs)? If not, or if you want a little refresher, click the image below to view our interactive CSO explanation.

CSO Capture Compliance Schedule

Prior to Save the Rain, the County captured 74% of combined sewage and stormwater flows. This means that on an average year about 25% of combined sewage and stormwater flows were left untreated. These flows entered Onondaga Lake tributaries and eventually made their way to the Lake where they degraded water quality.

The ACJ set a compliance schedule that mandated the County capture a certain amount of this combined sewer and stormwater volume by specifics dates. The table below shows these capture milestones and dates.

CSO Capture Status

We are extremely proud of our capture achievements! As the table above shows, we have hit every milestone. In fact, we achieved the 95% capture milestone a few years ahead of schedule. But we didn’t stop there! We now capture 97.6% of combined sewer and stormwater flows. This exceeds our mandate and means that on average only about 2.4% of these flows go untreated.

Each year we are constructing more projects to help get this number as close to zero as possible. Check out the table below for more information about our capture milestone timeline.

Combined sewage generated – Average volume of sewage and stormwater (in million gallons) per year that is generated in the community and by weather events. Data from the County’s 2009 input to the EPA’s Stormwater Management Model (SWMM).

Combined sewage conveyed to Metro – Average volume of sewage and stormwater (in million gallons) that makes its way to the Metro plant for treatment. Data from the County’s 2009 input to the EPA’s Stormwater Management Model (SWMM).

Additional combined sewage eliminated or captured for treatment – Average volume of combined sewage eliminated or captured for treatment beyond Metro (in million gallons). Combined sewer flow elimination happens when a sewer separation project occurs. This type of project separates pipes that convey sewage flow from pipes that convey stormwater flow. This type of project is expensive and occurs only when cost effective. Combined sewer capture happens when grey or green infrastructure projects intercept stormwater before it enters the sewer system. This helps our combined pipe system avoid overflows during storms. Visit this page to learn more about the over 220 Save the Rain green infrastructure projects.

Total combined sewage eliminated or captured for treatment – Average of all of the sewage and stormwater captured or treated at the Metro treatment facility or by gray and green infrastructure projects (in million gallons).

Percent capture – This value shows the amount of combined sewage flow (in million gallons) that is treated at Metro or by gray and green infrastructure projects as a percent of the total combined sewage generated in the community per year. A higher percentage equals a higher volume capture rate.