Where does the groundwater come from?

The deep aquifer has a strong hydraulic connection to the Columbia River. The deep wells show a clear tidal response and the fluctuation of the static water level inside the well column correlates closely with changes in tide. Isotope analysis is a way to match water chemistry signatures of different water sources and draw inferences about where it is coming from.

Although the actual water chemistry is different between the Columbia River and the deep aquifer due to filtration through thick layers sand, silt and gravel, the isotope analysis indicates the deep aquifer is recharged by the Columbia River.

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?