Water Solutions for our Future By Carey Gazis
“Water is the elixir of life,” reads many an introduction to the hydrologic cycle. Water is magical. We drink fresh water daily, sometimes mixed with other less-necessary things, to stay healthy and alive. We pour it on seeds in soil to grow food. We use it to wash our bodies, our clothes, our food, and our dishes. We, like all living beings, need water to survive and thrive. Animals that live in fresh water, like the mighty salmon, are especially dependent on water amounts and conditions for every stage of their life: enough water to move when they need to, quiet places to stay safe and grow when they are small, and cool environments in the hot summer months.
Historically, humans first turned to surface water—rivers, lakes, and streams—to meet our needs. Eventually, this water use included man-made ditches and canals that diverted water from the surface to irrigate crops on bordering lands. In some locations, springs spurting water straight out of the ground with no surface source, were also used as a fresh water supply. Springs were an obvious groundwater source to use, but humans also dug to access water. Dig far enough below the surface, and eventually you will reach saturated ground. This point, where standing water replaces the earth material that has been removed, is called the water table. With time, humans developed more complex ways to dig into the subsurface to extract more water from deeper sources.
The industrial revolution and the rise of large-scale agriculture has increased groundwater use exponentially. This makes sense given the much greater quantity of fresh water beneath the surface than on top. Globally, the groundwater supply is approximately 60 times greater than the supply from lakes and rivers. However, groundwater is prone to misuse by contamination with pollutants and depletion from over-pumping. Proper management of this water source is essential for our future well-being.
You may be wondering how water gets below the surface in the first place. Rocks and sediments that hold and transmit water in the subsurface are called aquifers. The term “aquifer” comes from the Latin words aqua, meaning water, and ferre, meaning to bear. Rocks and sediments “bear” water in small cracks and pockets between grains, sort of like an underground sponge. Water reaches aquifers near the surface by seeping beneath plant roots and eventually reaching the water table. It can also flow from lakes and rivers into the ground in some places. Deeper aquifers are harder to replenish, or recharge, since there are often layers above them that act as barriers to water flow. Sometimes, deep aquifers have been folded over time by geologic pressures and buckle up to the surface in places that become entry points for water recharge. But in most cases, water moves through the ground extremely slowly resulting in very old water in the deepest aquifers. In fact, most of the water there has not held the glint of daylight for hundreds to thousands of years!
In the Yakima River basin, where we live, there are three main aquifers. The shallowest consists of sand and cobbles that have been deposited by rivers, both modern and from the recent past. We geologists call this type of sediment “alluvium.” Deeper than that is an aquifer consisting of thick sequences of sediments—gravels, sands, clays—that fill the valleys in the Yakima basin. You can see exposed sections of this aquifer along the base of Craigs Hill near the fairgrounds or along the Palouse to Cascades Trail. In the Ellensburg valley, this aquifer extends to depths of approximately 2000 feet below the surface. The deepest of the three aquifers is composed of the Columbia River basalts. These are the black rocks that you see all over central and eastern Washington. They represent lava flows from massive eruptions that occurred millions of years ago. You can get a sense for how thick these aquifers are when you drive through the Yakima Canyon or along the Columbia River near Vantage. Water does not flow freely through the Columbia River basalts, but rather exists in intermittent horizons where the basalt is broken into rubble, usually because of gas bubbles and rapid cooling when it flowed onto the surface. Because there are multiple water-bearing units within the Columbia River basalts, we refer to it as an aquifer system. The enormous volume of the basalts means that this aquifer can supply the most water.
We depend heavily on groundwater in the Yakima River basin. Most rural homes located outside of towns like Ellensburg, Cle Elum, and Yakima, have relatively shallow groundwater wells (50 to 250 feet deep) to supply water for their household needs and outdoor uses. Many towns, like Ellensburg and Yakima, also rely on groundwater, but these wells tend to be deeper, tapping into water sources that are 500 to 1000 feet below the surface. In the case of Ellensburg, there are ten wells, many of them located in the parks around town. The largest use for groundwater, and fresh water in general, in the Yakima River basin is agriculture. Agricultural wells tend to be the deepest at approximately 500 to 2000 feet, and they draw the largest amount of water, usually from the basalt aquifer system. There are not many agricultural wells in the Kittitas Valley where most of the irrigation water comes from the surface. However, the areas around and below Yakima have many agricultural wells.
Water flowing in the Yakima River supplies the surface water to our region, and all of it is claimed through water rights. The river has been deemed “overallocated” because in dry years, some users do not get all their designated water. In other words, too many thirsty users are trying to drink from the same cup! Take this year—as of May 3, the Kittitas Reclamation District, and some others who have the same level of water rights, are forecasted to receive only 54% of their water. This is a severe challenge for maintaining our agricultural economy. It also presents a significant concern for the fish and other aquatic organisms that depend on specific streamflow and water conditions. Add to the overallocation issue a changing climate, which will result in more precipitation falling as rain rather than snow. This will mean less water stored in mountain snowpack into the summer and earlier peak water flows in the spring.
Is there a solution to our water woes? Yes! A diverse group of stakeholders in the Yakima Basin have come up with an exemplary long-term plan to create a more resilient water management system: The Yakima Basin Integrated Plan. It involves several strategies to conserve or store water, in addition to strategies for improving habitat and fish passage. This brings us to my favorite strategy: groundwater storage.
Groundwater storage is just what it sounds—using aquifers to store water underground in the same way that we use reservoirs, like Lake Keechelus and Lake Kachess, to store water on the surface. There are two main advantages to using the subsurface to store water. First, there is more storage space underground than on the surface. The total volume of these aquifers is enormous, and there is even more room now that we have withdrawn so much water, especially from the deeper basalt aquifers. Secondly, storage in the subsurface does not have the same environmental and infrastructure impacts as storage on the surface. There are no dams that prevent fish passage or cabins to be flooded by a reservoir.
A group called the Groundwater Storage Subcommittee of the Yakima Basin Integrated Plan is working to create and implement groundwater storage projects. The goal is to take water that flows over the surface in the spring—water which is flowing out of the Yakima basin into the Columbia River and eventually into the ocean, and that may cause flooding—and put it in the aquifers where it will be stored for later use. There are several challenges to work out, including where and when to withdraw water and which aquifers are best for storage. We also need to have a good understanding of what will happen to the water when it is put into the aquifer. Will it move? In which direction? And how quickly? I have had the good fortune to work on some of these questions with my students and colleagues at Central Washington University. Groundwater storage is an exciting management strategy and is key, I believe, to climate resilience in the western United States.
