Maintaining the water we can’t see

The importance of groundwater in the Dungeness watershed

Some of the most important activities in life take place behind the scenes. In the Dungeness Basin, it’s happening under the ground.

Although we aren’t usually aware of it, water is continually moving underground. This groundwater comes from the natural percolation of surface water, rainwater or snow melt into the ground and is the main source of drinking water for residents of the Dungeness Basin.

Declining levels of groundwater in areas of the Dungeness watershed are a concern. Population growth, seasonal water shortages, changes in irrigation practices and land use, and complex geology in a naturally dry area are some of the factors affecting groundwater levels. Careful management of groundwater supplies is crucial to the basin’s overall water supply.

Groundwater is contained in aquifers — underground geologic formations that store and move groundwater downslope to springs, streams and marine waters. The size and numbers of aquifers in the Dungeness vary tremendously across the watershed, so the availability of groundwater at any given location can vary as well.

In the summer months, groundwater keeps the local rivers and streams flowing. This is because all our water is connected. Withdrawing surface water affects groundwater and vice versa.

We have lots of good data about the Dungeness groundwater picture and always are gathering more. Sources include the U.S. Geological Survey’s studies and models, the Department of Ecology’s groundwater model and monitoring network, data gathered and analyzed by the Clallam County Department of Health and descriptive information from well logs submitted by drillers.

So who uses groundwater in the Dungeness watershed? People who rely on wells do. A number of residents get their water from small, single-owner wells, which are often referred to as “permit-exempt wells” because they do not require a water right permit. Many small community water systems also use permit-exempt wells.

Larger public water suppliers that hold water rights also depend on groundwater. The Clallam County Public Utility District serves residences in the Carlsborg area with water from a 177-foot-deep well. Residences in Sequim are hooked up to a city water system that gets much of its supply from large, deep wells in the Port Williams Road area.

Thousands of wells are already in use in the watershed and many more may be drilled in the future. As noted above, withdrawals from wells affect the amount of water in our streams and aquifers, especially in late summer and early fall when stream flows are already low. Fish and other aquatic species can be negatively affected — and so can water users with existing water rights.

Any single groundwater user probably is not going to have a big impact on the water supply. It is the cumulative use — the effects of many, many users taking water — that really adds up.

It is not just the amount of water used, but how it is used, that contributes to the overall impact.

For example, a house on a septic system will return to the aquifer much of the water used in-house (for bathing, washing, flushing). By contrast, a house connected to Sequim’s sewer system will have its in-house water treated and recycled at the city’s reclaimed water facility. In summer months, this water will go to the re-use park or be used for irrigation; in other months, much of it is discharged to the Strait of Juan de Fuca. Furthermore, a house that uses inefficient outdoor irrigation methods to water plants or grass all summer long will lose a lot of that water to evaporation.

Since all of our water is connected, it will take coordinated management of this scarce resource both to meet growing demand for water and to maintain and restore the environment we all cherish.

The third community forum on future water management in the Dungeness watershed is tentatively scheduled for September. Watch the Gazette for announcements.

The Dungeness River Management Team, rule advisory committees, interested local groups and citizens are collaborating with the Department of Ecology in the rule-making process. There are many opportunities for public involvement; see announcements in this paper and on the Ecology Web site (www.ecy.wa.gov/programs/wr/instream-flows/dungeness.html). Subscribe to the Dungeness e-mail list (scroll down to the e-mail heading at the Web site) to receive updates and new information. Questions? Contact Ecology’s Cynthia Nelson at 360-407-0276 or Sam Gibboney at 360-379-4831.