Why not move the water supply intake to a better location on the Cowlitz River or Columbia River?

Sediment Transport

The problems in the Cowlitz River with moving sandbars and turbid water are not specific to the location of the intake structure at River Mile 5.2. Moving the location of the intake structure to a wider or deeper section or a bend in the river that historically seems to stay scoured out does not address the larger problem of sediment transport. River training structures such as rock dike fields, submerged pile dikes and Iowa vanes have been suggested as a way to improve water flow but all of these would require extensive modeling evaluation and there is disagreement amongst river experts about whether or not it would work. Rock vanes installed in front of the intake structure in 2005 to promote flushing flows across the face of the intake were buried by sediment within the first year of operation.

Federal Approval

The Cowlitz River and Columbia River are federally defined as navigable waterways and fall under the jurisdiction of the U.S. Army Corps of Engineers. Construction in or over the river, excavation or discharge of material into the river, or any work which affects the course, location, condition, or capacity of the river requires approval and permitting from multiple state and federal agencies. The permitting process to construct a new intake structure on the Cowlitz River or Columbia River is expected to be lengthy, difficult and expensive.

To further complicate the situation, NOAA Fisheries is taking a close look at adding Pacific Smelt to the list of Endangered Species in response to a recent petition from the Cowlitz Tribe urging smelt protection in the Columbia River and its tributaries. Salmon and steelhead fish are already listed as endangered species, making the process and conditions of any permit to construct and operate a new intake very complex, if it is possible at all.


Finally, the cost of a relocating the intake to a presumed better location on the Cowlitz River or to the Columbia River, together with rehabilitating the existing water treatment plant, was evaluated early on in the planning process and determined to be not cost effective. In order to avoid similar sedimentation problems at a new intake on the Cowlitz River, the intake would need to be located upstream of the confluence of the Toutle River (the primary source of the sediment).

The distance from an intake structure at either location to the water treatment plant on Fisher’s Lane and the need for a river crossing in order to route a raw water main back to the plant make the total project cost prohibitive. In 2007, the cost to install an intake structure upstream on the Cowlitz River and rehabilitate the existing water treatment plant was estimated at $66 Million. And the cost to install a Columbia River intake and rehabilitate the existing water treatment plant was estimated at $72 Million.

Show All Answers

1. Why does my tap water appear to be discolored?
2. Why didn't we rebuild the Fisher's Lane water treatment plant?
3. Why didn't we stay with the Cowlitz River?
4. How long will the groundwater supply last?
5. Will the groundwater stain my laundry and household fixtures?
6. Why not move the water supply intake to a better location on the Cowlitz River or Columbia River?
7. What is in the groundwater?
8. Until how long is the groundwater supply expected to last?
9. How do I know the groundwater won’t become contaminated?
10. Where does the groundwater come from?
11. Has there been a change in the pH levels after switching to the new water source?
12. What if the water smells funny?
13. Should I consider getting a water softener?
14. What can I do about hard water?
15. How does hard water impact my life?
16. What is the City doing to reduce hardness?
17. What is the hardness of the City's new groundwater source?
18. Where do hard water minerals come from?
19. Is hard water safe?
20. What is water hardness?