STATIC WATER LEVELS

Columbia Basin Groundwater Management Area

 Prepared for the
Columbia Basin GWMA Board of Directors

Prepared by
John Porcello / GSI Water Solutions
Walter Burt / GSI Water Solutions
January 22, 2009


TERMINOLOGY for BASALT AQUIFERS


Shallow          à          Wanapum Basalt
Intermediate   à   Upper Grande Ronde Basalt
Deep              à   Lower Grande Ronde Basalt


CONCLUSION #1


There Is Little, If Any, Groundwater Movement Vertically Between The Basalt Aquifers
Each Aquifer Is Separate and Distinct
 
Shallow (Wanapum)
Intermediate (Upper Grande Ronde)
Deep (Lower Grande Ronde)


GROUP OF NESTED OBSERVATION WELLS
Groundwater Elevations since 1981

Groundwater Elevations since 1971

Groundwater Elevations since 1981

Groundwater Elevations since 1971

Groundwater Elevations since 1973

The Water Level Data Tell Us Two Things

The Basalt Aquifers Are Separate And Distinct

Water Levels In The Deep Grande Ronde Are Declining   

How Does This Relate To
Geologic and Geochemical Information?

What does it all mean for the future?

CONCLUSION #2

Natural Recharge Is Minimal and Slow
  • Few Places For Recharge To Grande Ronde Basalt
      • Few places where interflow zones outcrop
      • The interflow zones are thin
      • Shallow basalt zones don’t leak to deep zones
  • Only Natural Source: Precipitation
      • Winter/spring runoff
      • Small in magnitude compared with pumping
  • Long distances to wells à extremely slow process

 

 Water Levels

 

CONCLUSION #3

Existing Groundwater Supplies In The Deep Basalt Are Not Reliable Or Sustainable In The Long-Term 

(Lower Grande Ronde) 

Continuing to Deepen Wells Into the Lower Grande Ronde Is Only A Temporary Solution 

(Declines in Water Levels and Pumping Yields) 

 

 

Last Updated ( Thursday, 19 March 2009 )