Water Matters: Seeking equilibrium

More than 25 years ago I wanted to share a hydrologist’s delight that Sequim’s annual Irrigation Festival coincided with “National Drinking Water Week,” and the Sequim Gazette was kind enough to run a Guest Opinion piece I wrote on May 5, 1993. Here is an excerpt:

“’Drinking water and irrigation — there’s a connection’

“Hopefully no one is drinking untreated water from irrigation ditches anymore, so what is the connection? As many of you with shallow wells may know, the connection can be pretty strong. Dungeness River water, flowing through more than 100 miles of irrigation ditches, filters down into groundwater throughout the Sequim-Dungeness Valley. Some of that groundwater may be feeding your well and pumped into your house for drinking.

“ … These days, most well drillers drill deep enough to penetrate through a layer of fine-grained sediment before they finish a well. This is a good practice for several reasons. First, the deeper the well, the less it is dependent on recharge from an irrigation ditch, stream or river. The water in deeper zones mostly comes from upgradient recharge areas, possibly as high as the foothills or the Olympics. Also, fine-grained layers provide some natural protection for your drinking water source from many contaminants.

“The amount of leakage from the irrigation ditch system depends on the recharge capacity of the underlying strata, the soil in the bed of the ditch and the amount of water flowing in the ditch. It is very difficult to estimate the actual amount of water which leaks out of the ditch system as a whole ….”

————

Ten years and several major projects later the basic message was still relevant. The following excerpt was published in the Gazette on May 14, 2003:

“’Where water can be wealth — for fish, farms and people’

“ … Since then (10 years ago) we have learned a great deal about the groundwater system and how it interacts with streams and ditches. For example, three decades of eliminated leaks in the (irrigation) ditch system, improving on-farm efficiency, and residential development has radically changed the overall hydrology of this area.

“Indeed, the last time the hydrology changed so much was probably 100 years ago when the ditches were built, river water was spread across fields, and the water table under the Sequim Prairie rose up to subsidize Gierin, Cassalery, Hurd, Matriotti and other creeks (and wells).

“ … Back when Dungeness River water soaked into the Sequim Prairie by the acre, a man-made ‘hydrologic equilibrium’ was established — to the benefit of settlers but, we now know, at the expense of our co-inhabitants, the salmon. With recent and planned changes to the irrigation system, the hydrology will eventually reach another equilibrium, one that will restore natural streamflows in the river when fish need them. The associated cost …

“The valley’s prevalent coarse soils led to much of it being designated a critical aquifer recharge area, allowing for special groundwater protection measures when land use decisions are made to prevent contamination and maintain natural recharge volumes … We have learned — the hard way — just how susceptible our groundwater is … for some residents of Agnew, the groundwater flowing from their kitchen tap contains nitrates exceeding the (federal water quality) standard for drinking.

“Unfortunately, the cause of this contamination has not yet been determined since nitrate can come from many sources, including septic systems, fertilizers and animal waste. Because it is so easy for groundwater to become contaminated, and difficult or impossible to clean up, all of us need to prevent contamination at our homes and businesses. We do this at home by maintaining our septic system, soaking up oil spills, using chemicals sparingly or not at all, etc.

“ … This week’s watershed articles remind us that the irrigation-drinking water connection is still there and always will be to some degree.

“In 10 years we’ve come a long way, but the bottom line hasn’t changed: Clean groundwater is a precious but vulnerable public resource and we must be vigilant to keep it that way.”

Nevertheless, she persisted

Fast forward another 16 years and here I am again, celebrating irrigation and drinking water in Sequim in early May. Some things never change — but others are worth reporting on:

• The population of the prairie has risen by about 25 percent and we now have rules in place, thanks partly to water right transfers by irrigation managers, to prevent over-taxing the surface and groundwater system with growing drinking water needs. The proposed off-channel reservoir is another piece of the puzzle needed to achieve balanced equilibrium as we face modern climate change.

• The nitrate level in some wells has abated but in others it continues to rise. Extending the city sewer to Carlsborg is preventing a lot of nitrogen loading to the aquifer, but it will take time for legacy nutrient contamination from septic systems and historic dairy farms to decrease significantly.

• Another necessity to reach equilibrium is to prevent what scant rainwater we get from draining to the sea. Improving stormwater and water quality management is the subject of current grant projects for the City of Sequim as well as Clallam County.

Finding my old Gazette articles reminds me how much I love our small town newspaper and how it facilitates sharing and connections within our community.

In addition to the above special occasions, have a happy and healthy Bike Month!

Geek moment

The savings account for Water Year 2019 has reached its maximum balance. The snow that accumulated in the mountains between October and April determines what flow levels will look like in the Dungeness River during the heat of the summer. Temperatures between now and then determine whether it melts and flows into the Strait sooner, versus later.

In summary, “snow water equivalent” at the Dungeness Snotel was still above 75 percent of normal for the first half of April, but by the third week the snow was gone whereas the median of all years on record is still about an inch.

One can’t closely predict how these statistics translate to summer streamflow since our watershed’s mountain weather station is low in elevation (at about 4,000 feet) and has a relatively short period of record (only 20 years). Looking at other Olympic Mountain stations gives a better average for the entire range, and they say we’re at about 50 percent, at best – compared to 130 percent this time last year (reference: Olympic National Park field staff).

For the 2019 Water Year (started Oct. 1, 2018):

• Rain in Sequim through April 28 at the Sequim 2E weather station (sea level): Total rainfall = about 13 inches; Highest and lowest temps haven’t changed = 65 and 15 degrees F in October and February, respectively.

• Snow at the Dungeness SNOTEL station (elev. 4,010 feet) through April 28 at midnight: Snow depth = 0 inches; Snow water equivalent = 0 inches. Number of days below freezing = 22 (no change).

• River flow at the USGS gauge on the Dungeness (Mile 11.2): Maximum flow = 1,870 cubic feet per second (cfs) on Nov. 27; Minimum flow = 77 cfs on Oct. 25. Currently = 350 cfs. Range for the past month = 200-600 cfs.

• Flow at Bell Creek entering Carrie Blake Park: trickle; Bell Creek at Washington Harbor = flow generally between 2-5 cfs in winter-spring unless it’s storming.

Ann Soule is a hydrogeologist immersed in the Dungeness watershed since 1990, now resource manager for City of Sequim. The opinions expressed are those of the author and do not necessarily represent policies of her employer. Reach Soule at or via her blog at watercolumnsite.wordpress.com.

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