ALCOSAN has embarked on a comprehensive, $2 billion, long-term Clean Water Plan that will significantly reduce the overflows of diluted, untreated wastewater into the region’s rivers; thus, significantly improving the water quality of our local waterways. More specifically, the Clean Water Plan will:

Our Challenge

It is estimated that nine (9) billion gallons of overflow enter our rivers and streams during heavy rain and snowmelt events. ALCOSAN’s Clean Water Plan will reduce the overflow by approximately seven (7) billion gallons.

About the Plan

The Clean Water Plan is our blueprint to address the water quality in the rivers and streams across our service territory, as directed by our Consent Decree.

The Consent Decree spells out what ALCOSAN must do to comply with the Clean Water Act by reducing combined sewer overflows. 

Learn more about the Clean Water Plan and the Modified Consent Decree

The Plan is designed to be affordable, flexible enough to adapt to evolving technology and regional in scale.


The overall cost was reduced and the timetable extended to 2036 – protecting customers from rate increases beyond their ability to pay.

See if you are eligible for bill pay assistance


The Plan first considers green stormwater infrastructure to better identify future system capacity needs.

Take a look at green infrastructure projects
Learn about Preliminary Planning


The plan extends ALCOSAN’s responsibilities for maintenance – reducing the burden on municipalities.

Understand the Regionalization Program

9 Billion Gallons of Overflow

7 Billion Gallons of Overflow to be Reduced

600 Gallons to be Treated Per Day by 2028

22 Million in GROW Grants Distributed