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Forgotten Code – The Strategic Groundwater Reserve for the State Capitol

In 1986, Washington State adopted WAC 173-591 – Reservation of Future Public Water Supply for Thurston County – pursuant to the Water Resources Act of 1971. It followed the year after the legislature had passed RCW 90.44 to regulate public groundwater, which included a provision that recognized the need to manage groundwater aquifers for future use. Thurston County’s aquifer fulfilled two of the criteria to establish a groundwater management area -it was a sole source aquifer designated by the federal EPA, and it was the primary source of supply for public water systems.

The strategic groundwater reservation occupies the larger part of northern Thurston County, stretching from Hawks Prairie and McAllister Springs south to Black Lake and the airport and west to Allison Springs.

In 1986, the Department of Ecology found that to provide peaking capacity on a daily basis, the maximum annual withdrawal should be 22,931 acre-feet/year and that annual withdrawal for all sources “shall not exceed 48,225 acre-feet/year. This is intended to serve the estimated population of 288,092 in fifty years.”

(Note: An acre-foot covers a football field about 1 foot deep, equivalent to 43,560 cubic ft. of water)

Yet, here we are just 38 years later with a population of over 300,000 and no clear idea of exactly how much water is being withdrawn from our sole source aquifer. The county has a budget for all its monetary expenses, but where’s the budget for how we’re spending our most precious resource, water? How do we plan for the future, especially with the present reality of climate change which incredibly, is not now even considered when granting water permits, if we don’t even know what we have now?


The Department of Ecology has been aware of the dwindling supply of water for decades. Water is not directly owned, but granted for beneficial use by way of water rights. In fact, Ecology has been trying to claw back water rights that were granted years ago. Surface water rights granted after 1919 and groundwater rights granted after 1945 were treated as separate entities. The reality of hydraulic continuity that recognizes surface and groundwaters are NOT separate resulted in more rights being granted than there is physical water to supply.

By 1950, significant restrictions were in place in Thurston County, and by 1988, the entire water supply of the county was allocated. After 1988, any development had to obtain water through existing water service providers with water rights, or through small permit exempt wells used by single family residences where there is no hookup to city utilities. (See League of Women Voters of Thurston County 2023 Water Study p.18)

In 1998, the US Geological Service did a hydrogeological report on the groundwater of northern Thurston County, an area of which the strategic groundwater reservation occupies a large part. The data collected in 1988 and 1989 raised concerns about the continual increase in demand and a lack of alternative water sources, as well as the aquifers’ susceptibility to contamination due to its highly porous nature and the use and spillage of hazardous materials. The report stated, “the possibility of increased natural recharge on a long-term basis appears remote. In fact, the trend of increased residential development and central storm sewers may result in decreased recharge.”

At that time when the population was just 123,800, total withdrawal was estimated at 37,000 acre-feet. This included all users – public water supplies, domestic wells, commercial, industrial and institutional users, irrigation, aquaculture and livestock. Compare that to 65,488 acre-feet of groundwater used in 2023 for an area roughly the same size as the 1988 study area. (See League of Women Voters of Thurston County 2023 Water Study p.14)

We may not know how much we are overdrawing our aquifer, but there are clear signs that we are. Streams that used to run all summer are drying up earlier and for longer, impinging on spring and fall salmon runs. Some shallow aquifers are already failing in localized areas. Wells must be dug deeper before hitting a reliable source of water. The USGS study reported the medium depth of wells as 105 ft in 1988. Today, according to one well driller, 150 ft. is more likely. Also, contamination is being found in shallower well water, making deeper wells necessary.


WAC 173-591 addresses water quality, stating:

“It shall be the policy of the department to protect the quality of the groundwaters of the state and in relation thereto to discourage any withdrawal facilities, construction methods, water use, or disposal practices which would contaminate or otherwise reduce the quality of the groundwaters or impair the beneficial uses of groundwaters of the state.”

Since 1986, more than 100 contaminants of emerging concern have been identified by the EPA.  Thousands of chemicals have been identified in Puget Sound, but the county did little to no testing for them in our groundwater until recently. Thurston County’s Environmental Health Technical Memo #77 describes a study in the Tri-lakes area around Long, Pattison and Hicks Lakes that tested for impacts from septic systems to the area’s groundwater.

The study found nitrate contamination entering the groundwater, likely from septic systems around the lakes, many of which were installed prior to the adoption of more stringent regulations, and from other sources. The previous modeling used to estimate the amount of contamination was found to underestimate actual nitrate concentrations, which were 1.41 times greater than predicted. Surface water sites were also found to be contaminated.

Additionally, samples were taken for chemicals of emerging concern. The presence of pesticides/herbicides, industrial chemicals, commercial chemicals, pharmaceuticals and food additives in numerous wells were detected. The study recommends additional sampling and analysis to assess human health risks.

Another alarming finding of the study was that contamination is reaching below confining layers and seeping into deeper aquifers. This downward pull in most parts of the study area is exacerbated by increased and deeper groundwater pumping to satisfy our growing population. Having unchecked contamination sources, like faulty septics, over a long period of time also contributes to deeper contaminant concentrations.


The League’s Water Study calls for urgent action to adapt to the widening disparity between water use and availability as our population increases. Our water supply, which relies almost exclusively on precipitation, is projected to remain stable on an annual basis, but climate change will bring shorter, warmer, wetter winters and longer, hotter, drier summers, altering seasonal rain patterns. The predicted heavy winter rains will be lost to runoff instead of being absorbed by the earth to replenish the aquifers. That loss reduces the amount of cool groundwater in streams needed for fish habitat, reduces moisture in soils negatively impacting forest health and agriculture, and increases the concentration and spreading of pollutants from land-based to freshwater resources.

Today, Ecology requires that any new water use must guarantee adequate water is available and include mitigation measures to make up for the water withdrawn. One such mitigation is OlyEcosystems’ Deschutes River preserve whose wetlands are being restored to serve as a floodplain where winter water will be captured to sustain stream flows during the dry summer, providing valuable habitat for juvenile salmon and other wildlife. In fact, restoring wetlands to protect the habitats of our endangered species is one of the best ways we can mitigate our water use.

Besides conservation, how can we get more water back into the ground? Reducing timber harvests and restoring the forests that filter and slow down rainfall, introducing beaver ponds, and constructing ponds and wetlands are much less costly than building reservoirs or artificially injecting winter stream flows into injection wells to channel it below to the aquifer. Half of the LWV study is devoted to solutions, including forming a regional intergovernmental approach to coordinate today’s existing fragmented planning and management, split between the cities, LOTT, private and public water suppliers, the Port, fire districts, drainage districts, lake management districts and shellfish protection districts.

But for any of these strategies to work, the question still remains – How much water is in the strategic groundwater reservation, our sole source aquifer, and of what quality? The county and Ecology cannot know if they are abiding by the regulations of WAC 173-591 without a water budget, an accounting of what is being used and what’s left. A water budget determines all the inflows and outflows at a sub-basin level, information from which one can determine what is a safe yield of water from wells and streams. It would also allow forecasting of climate induced changes to availability, a gaping deficiency in today’s permitting decisions.

A water budget is achievable with new scientific models and data. By committing to this vital research, the state and county can act proactively to ensure water is plentiful and healthy into an uncertain future.

Esther Kronenberg regularly reports on water issues

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