Op-Ed

Time to get serious about water-use efficiency

We can irrigate our lawns and gardens more efficiently by watering only in the early morning and not overwatering.
We can irrigate our lawns and gardens more efficiently by watering only in the early morning and not overwatering. The Wichita Eagle

First of two parts

It’s not a silver bullet, but improving the efficiency with which we use water could and should be an important part of our strategy to resolve local water problems.

What problems? Whatcom County gets lots of rain and snow most winters (but not last winter). True, but winter precipitation may not help during the summer when water usage is high and water supply is low. As a consequence, flows in the Nooksack River, its tributaries and the three forks are often too low to meet the Department of Ecology’s minimum instream flow requirements. Indeed, Ecology’s rule is not met almost two-thirds of the time during the critical summer months of July, August and September.

Fortunately, abundant water-use efficiency opportunities exist in all sectors of society: residential, commercial, industrial and agricultural.

This timing disparity will likely get worse as Whatcom’s population continues to grow and as the effects of global climate change become more severe. These changes include less glacier mass, more precipitation falling as rain and less as snow, earlier snowmelt in the spring and less rain and higher temperatures in the summer.

Benefits

Improving water-use efficiency can provide enormous economic, resource and environmental benefits, and help protect against the adverse effects of drought. Reducing water use through efficiency:

▪ Allows that water to be used for other human purposes or left in the creeks and Nooksack River to benefit salmon and other wildlife and to enhance recreational and scenic values.

▪ Substitutes for water-supply projects that might cost more to build and operate.

▪ Cuts the amount of water sent through water and sewage transportation and treatment systems.

▪ Saves energy.

▪ Saves money on the costs to treat and pump water and sewage.

Efficiencies

There are two ways to improve efficiency: technologies that provide the same or better services with less water, such as low-flow shower heads and toilets that are more efficient than their traditional counterparts, and operating practices and behaviors that use less water, such as more careful and sophisticated scheduling of irrigation to improve agricultural productivity and save water without new hardware.

Fortunately, abundant water-use efficiency opportunities exist in all sectors of society: residential, commercial, industrial and agricultural. In our homes, we can replace inefficient fixtures with more efficient ones, including toilets, clothes washers, faucets and sprinkler systems. We can irrigate our lawns and gardens more efficiently by watering only in the early morning and not overwatering.

The commercial sector offers many of the same opportunities as the residential sector. In addition, kitchens, laundries and office buildings offer large savings not possible in our homes. For example, a standard water-cooled ice maker uses 156 gallons of water per 100 pounds of ice, compared with only 20 gallons for a high-efficiency air-cooled unit. Switching to the high-efficiency model cuts electricity, water and sewer costs by almost 60 percent.

Recirculating the water used in industrial cooling towers could save considerable water (as well as chemicals and money). Also, countercurrent equipment for rinsing and cleaning is typically the most water-efficient method. The cleanest water is used only for the last stages of a rinse operation; water for early rinsing tasks, when water quality is not as important, is collected from water used during later stages in the process.

Agriculture

Because agriculture accounts for 72 percent of summer water use in Whatcom County, this sector may be the most important for water-use efficiency. Fortunately, many options exist here as well. Without changing the type of irrigation system or irrigation scheduling, large water savings are possible. For example, shifting from systems with average efficiency to those with maximum efficiency (e.g., from 88 percent to 95 percent for drip systems) would cut Whatcom irrigation water use by 11 percent.

Washington State University developed software that farmers can use with a personal computer or smartphone to schedule their irrigation systems (when to turn on and how long to water) for the next seven days on the basis of various factors, such as soil type and depth; soil moisture; recent, current, and forecast weather conditions; type of crop; and irrigation system efficiency. According to WSU, “Improved irrigation scheduling … [could] decrease irrigation water use by 10 to 30 percent while resulting in equivalent or better crop yields and quality.”

Given the many different ways to improve water-use efficiency, what is happening? We are making progress as measured by long-term declines in per capita water use in Bellingham, Lynden and perhaps other local cities. Water use for the three large industrial facilities at Cherry Point has also been declining over the past decade. No data are available on agricultural water-use efficiency because most farm water use is not metered or metered but not publicly available.

Coming Aug. 31: Steps we should take to realize water-use efficiency benefits.

Eric Hirst holds a doctorate in engineering from Stanford University and worked for 30 years as an energy policy analyst at Oak Ridge National Laboratory. Since moving to Bellingham, he has served on three advisory committees for the city of Bellingham, was involved with the formation and early operation of the Whatcom County chapter of Futurewise and served on the board of RE Sources for Sustainable Communities.

  Comments