Whatcom County water use in 2010 was almost 33 billion gallons a year, equivalent to 450 gallons a day for every person in the county.
Who cares? Why is it important to know how we use water? Data on water use, by sector and time of year, are essential inputs to good policy decisions. These decisions affect the amount of water left in streams and the Nooksack River to support salmon, trout and steelhead listed as threatened under the federal Endangered Species Act. These data are needed to determine the Lummi and Nooksack tribal treaty rights to salmon harvests as well as water rights for their reservations. As water becomes scarcer, we need data to demonstrate the effects on water use of changes in: agricultural crops, farm practices and irrigation technologies; summer outdoor use in households; and efficiency measures in the residential, commercial and industrial sectors. Whatcom County policy calls for promoting “the efficient use, conservation and protection of water resources.” Without good data on actual (not estimated) water use, we’ll never know whether these programs are working.
Slightly more than half (57 percent) of the water we use is from surface water, and the remaining 43 percent is from groundwater (wells). Irrigation is, by far, the largest water use, accounting for 38 percent of the annual total. Industrial use accounts for 26 percent; homes for 22 percent; livestock for 4 percent; and aquaculture, mining and commercial account for the remaining 10 percent. Lynden households use about 160 gallons a day, rural households about 60 percent more than Lynden, and Bellingham metered households about 10 percent less than Lynden.
Because Whatcom’s water problems occur during the summer months, when usage is high and precipitation is low, it helps to divide these annual totals into three seasons: summer (July, August and September); winter (November, December and January); and the other six months. The three summer months account for almost half the annual total, compared with only 13 percent for the three winter months. Thus, summer water use is almost four times greater than winter use.
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Agriculture’s share of the total is much greater in the summer than year round: 65 percent vs. 42 percent. Of agriculture’s 65 percent share of summer water use, 63 percent of that is from irrigation.
The key challenge in estimating local water use is the lack of metering for many water consumers. In particular, many (perhaps most) farms and rural homes are not metered. Even if their usage is metered, the results are not recorded on a regular basis and are not publicly available.
The primary source for the annual figures is the U.S. Geological Survey, which estimated water use for 2005 and 2010. Because of changes in data definitions, quality and comprehensiveness between these years, I am not able to show how Whatcom water-use allocations and trends changed over time.
The USGS report does not estimate commercial water use because there is no clear definition of what users should be in the category. I used data from Bellingham and Lynden to estimate county-wide commercial-sector water use.
Whatcom Farm Friends calculated agricultural water use by month for irrigation. Its numbers are based on estimates of monthly water use by crop. I obtained monthly electricity-use data for Whatcom County irrigators from Puget Sound Energy. These two sets of estimates show irrigation water peaking in July or August. Because metered data are not available for agricultural water use, I used the USGS annual total and the Farm Friends/PSE allocations to calculate irrigation numbers for the three seasons.
I used several sources to allocate annual water use to the three seasons. I used monthly data from Bellingham and Lynden to calculate the percentages of residential and commercial consumption for each month and then aggregated the monthly numbers to the three seasons. I used monthly data from Public Utility District No.1 on its industrial users (primarily the three large facilities at Cherry Point) and data from Bellingham and Lynden for the rest of the industrial sector.
Agriculture, especially irrigation, dominates Whatcom water use, especially during the critical summer months. Irrigation accounts for almost two-thirds of summer water use. Other estimates of irrigation water use are even higher.
Estimating Whatcom water use is challenging because so much usage is not metered and reported and because the definitions, comprehensiveness, and accuracy of data sources vary over time. Resolving local water issues requires more complete, better defined and accurate data on water use. We need such data to measure efficiency improvements and to allocate water to instream and out-of-stream uses. For example, per capita water use in Bellingham dropped by about 4 percent a year over the past two decades. It is not possible to make a comparable statement about agriculture because such data do not exist. Advances in computing and communications technologies make it cheaper and easier to meter and remotely read water use, largely eliminating the need for estimates and assumptions.
ABOUT THE AUTHOR, SERIES
This is one of a continuing series of columns about the water problems and potential solutions in Whatcom County.
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 more than 12 years ago, 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.
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