Climate change complicates Nooksack adjudication  - Salish Current
April 18, 2024
Climate change complicates Nooksack adjudication 
Eric Hirst

Some Nooksack Basin water users will hold paper rights that bear little relationship to the amount of water actually available, unless adjudicators factor in climate-change-driven projected declines in water supply, a commentator says. (Glen Nelson Bristow ©)

April 18, 2024
Climate change complicates Nooksack adjudication 
Eric Hirst


The essays, analyses and opinions presented as Community Voices express the perspectives of their authors on topics of interest and importance to the community, and are not intended to reflect perspectives on behalf of the Salish Current.

Commentary: What happens when property owners hold legal water rights that bear little relationship to the amount of water actually available?

Adjudication of water rights in the Nooksack River basin, expected to begin within a few weeks or months, will provide an inventory of water rights. Specifically, a Whatcom County Superior Court judge will determine who has the right to use water — where, when, for what purpose(s), with what priority date and how much.

Nooksack River summer streamflow at Ferndale, in cubic feet per second (cfs). (USGS)

This inventory, however, will likely not relate well to the actual availability of water. That is, the amount of paper water deemed legal may be less — substantially less — than the amount of wet water that is present in aquifers, creeks, the three forks, tributaries and the mainstem Nooksack River. 

This shortfall, which already exists, will almost certainly be made much worse by the adverse effects of climate change. 

Overall, measured summer flows on the mainstem, three forks and one lower Nooksack tributary are declining.

These declines are worsening over time. Flows during the past 15 years decreased much more rapidly — 5 to 10 times as fast — than during earlier years.

These declines are associated with several factors, including earlier spring snowmelt, diminishing glacier mass (North Cascades glaciers have shrunk by almost 40% during the past four decades), higher summer air temperatures (which increase evaporation from surface waters) and lower summer precipitation.

North Cascades glacier loss, 1985–2022. (Environmental Studies Program, Univ. of Oregon)

Because of these changes, conditions for salmon (and other wildlife) have become worse and worse, relative to the flows set in 1985 by the Washington Deptartment of Ecology instream flow rule. 

Ecology’s rule is based on science that is four decades old. Updating these results would surely require higher minimum flows. Indeed, more recent work shows that optimal flows for fish are substantially higher than the minimum levels set by Ecology two decades earlier.

Several organizations have analyzed the likely effects of climate change on future streamflows throughout the Nooksack basin. Their projections differ in the specifics. However, they all agree that flows during the summer months will be substantially lower than they are today. As an example, one projection, from Western Washington University, showed that flows in the three forks and mainstem in 2050 are expected to be lower by 33% to 58%, relative to the 1950–2010 median. And today’s flows are already much lower than historical flows.

Implications for adjudication

These historical and near-certain future declines in water supply have major implications for the Nooksack adjudication. Unless Ecology and the court explicitly account for climate change in assigning water rights to the tribes, farmers, rural homeowners and water utilities, some entities will hold paper rights that bear little relationship to the amounts of water actually available. What happens then?

Projected changes in streamflow for 2050 for four locations (relative to 1950–2010 medians). (R. D. Murphy, Western Washington Univ.)

Obtaining a legal water right through the adjudication process does not mean one will be allowed to use that water during the low-flow summer months, because real water will be apportioned to rights holders based on the priority date of those rights. The oldest rights will get water first, and if there is not enough water the newer rights will be turned off when flows are low. The most senior rights surely belong to the tribes; thus, others may be required to curtail summer water use unless we develop substantial new water-use efficiency, water storage and water supply resources. 

Ecology can avoid complicating an already challenging process and ignore the near-certain effects of climate change on availability of water. Or it can seek legislative authorization to explicitly incorporate the likely declines in water supply into the adjudication process. Although the second option will lengthen adjudication, failure to assign water rights that reflect real-world conditions will yield legal results that are worth little in practice.

For more details on the analysis that underlies these conclusions, see “Climate Change and the Nooksack Adjudication.”

— By Eric Hirst

[Ed. — Disclosure: Eric Hirst serves on the Salish Current board of directors.]

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