"Impacts to public water supplies from aquifer drawdown may adversely affect public water supply utilizing the shallow groundwater resources through springs and wells in the vicinity. The primary resource that may be affected is the spring system used by Fort Lewis (now JBLM)."According to Cal Portland:
Impacts on public water supply is discussed in detail in the Final EIS, page 3-61:
“The model predicted a drawdown of less than 0.25 feet at the spring location used for water supply to Fort Lewis. Based on the elevation of the pump intakes used for water supply in relation to the water level, the diversion structure can apparently accommodate a water level change of this magnitude, and therefore the Fort’s water right should not be significantly impaired by the construction of North Sequalitchew Creek. However, the pump station design details should be confirmed prior to construction.”Fort Lewis (JBLM) Contests
This interpretation of impacts is contested by Fort Lewis in a letter dated June 18,
2008:
“Although the document characterizes the impacts as minor, we do not share this view. The spring is already subject to seasonal fluctuations and often has to be pumped at a reduced rate in the summer months. Any decrease in the spring height, even one as small as a few inches would be a significant impact and would reduce our ability to provide clean, healthful water to our soldiers and their families. I should also point out that the hydrologic model used to estimate the impact to the spring is just that: a model. Models all suffer from a margin of error, which can be substantial in a complex system like the Vashon aquifer. With all due respect to the model and its creators, it is possible, even likely that the actual effect on the spring could be much greater than predicted.”
(Sources: City of DuPont Staff Report, January 2009, pages 24-26, Central Pierce, WA Sole Source Aquifer)
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