Inflow and Infiltration Reduction Program (I/I)

I/I is rainwater or groundwater that gets into sewer lines through improper connections or damaged pipes and increases the amount of water that reaches our water resource recovery facilities, which we then have to treat. 

I/I also increases the risk of sewer overflows within the collection system.

Reducing I/I in key basins by 2040 would save approximately $120 million in required upgrades and expansion in the collection system and at our treatment facilities.

We’re teaming up with our partner cities that own and maintain their own sewer systems, which deliver wastewater to WES’ treatment facilities to reduce I/I and save our ratepayers money. WES has committed to fund 33% of these projects to help solve this regional issue. We’re pleased to report we have an I/I agreement in place with all of our service area cities.

The WES Technical Advisory Team (TAT) reviews proposals from member communities for program funding.

Projects approved

Member CommunityProject NameEstimated CostDate Approved by TATWES contribution
Oregon CityI/I Program Management$1,400,0003/31/2022$462,000
Oregon CityRivercrest Phase 3$2,900,0003/31/2022$957,000
GladstoneI/I Rehab Design$482,9113/31/2022$159,360
Oregon CityLinn Phase 1$2,900,0003/15/2023$957,000
Oregon CityLinn Phase 2$1,200,0003/15/2023$396,000

Crew inspecting pipes  
Inspecting the pipes

Closed circuit monitoring of pipe interior  
Close circuit TV cameras capture how easily unwanted water can seep into cracked pipes.

Interior view of a pipe  
Groundwater (infiltration) seeps into sewer pipes through holes, cracks, joint failures, and faulty connections.


150 Beavercreek Road #430, Oregon City, OR 97045

Office Hours:

Lobby hours
Monday to Thursday
7:30 a.m.–noon and 1–5 p.m.

Phone hours
Monday to Thursday
7:30 a.m.–noon and 1–5 p.m.

Customer service

Development services and permits

Related Events
Water Environment Services
Water Environment Services
Related News
Water Environment Services
Water Environment Services
Water Environment Services, Transportation and Development, Parks, North Clackamas Parks and Recreation