December 15, 2021
Community Voices / Is time running out? Streamflow trends in the Nooksack watershed
Eric Hirst

While streamflows in the Nooksack River watershed may be high enough for lively kayaking some days, overall summertime declines are creating problems for salmon and other fish and wildlife as well as farms and other users dependent on the water supply. (Elisa Claassen photo © 2021)

December 15, 2021
Community Voices / Is time running out? Streamflow trends in the Nooksack watershed
Eric Hirst

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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.

Given the incredible amount of rain and flooding during the past few weeks, it may seem strange to talk about water scarcity. Although we have ample water in the winter (often too much water), we have too little in the summer to support healthy salmon.

The Nooksack watershed provides water for salmon, other fish and wildlife. It supports 45,000 acres of irrigated farmland and Whatcom County’s people and their homes, businesses and industry. But supplies are limited, as evidenced by the poor state of salmon and the substantial amount of irrigated farmland that lacks legal access to water. Complicating this are the adverse effects of climate change. 

I analyzed changes in summer streamflows for five locations throughout the basin: mainstem Nooksack River at Ferndale; North, Middle and South Forks; and Fishtrap Creek. I focused on summer (July, August, September) because that is when flows are lowest, salmon and other wildlife are most likely to need more water than actually is flowing, and human use of water is greatest (primarily because of agricultural irrigation). Low flows contribute to elevated water temperatures which, if high enough, can be lethal for fish. And low flows reduce levels of dissolved oxygen and limit access to habitat, both of which are bad for fish. 

Over the past 55 years (1967–2021) Nooksack River summer streamflow, measured by the U.S. Geological Survey in Ferndale, has been declining, at an average of 0.5% per year. However, this adverse trend is accelerating: during the past 12 years (2010 through 2021), flows declined by 5% per year.

Overall summer streamflow declines on the Nooksack system have been accelerating over the past 12 years, USGS data shows. The greatest change has been noted on Fishtrap Creek, which runs southwest from Canada through Lynden.

Overall, flows on the mainstem, three forks and one lower Nooksack tributary are declining, although erratically and at different rates.

These declines are worsening over time. Flows during the past dozen years declined much more rapidly — roughly 10 times as fast — than during earlier years.

Looking at the future

According to the Tribal Climate Tool, flows in the Nooksack River are expected to be lower than current flows by about 20% in the 2050s. Also, summer temperatures are expected to increase substantially over the next few decades and summer precipitation is expected to decline, leading to greater use of water for irrigation.

Is time running out? Yes! I focus here narrowly on temporal changes in streamflow and do not address the causes of these declines. Nevertheless, I believe historical data and modeling results show clearly that climate change is a major contributor to the worsening decline in streamflows throughout the basin.

If flows throughout the Nooksack decline by 2% per year (roughly half the actual recent decline), flows will be lower by 18% in 10 years and by 33% in 20 years. (Don’t take these estimates literally. Extrapolating these trends would eventually show negative flows.) Thus we need to increase flows throughout the Nooksack basin — and do so quickly. 

For over two decades, we have conducted countless meetings among many groups, produced report after report, and implemented projects that marginally improved our water supply-demand situation. But we have yet to adopt an action plan with specific projects, including new supply, storage and efficiency projects, as well as land-use practices (especially forestry). In particular, we have systematically and consistently ignored the potential role of water-use efficiency projects and programs. 

Implementation would involve identification of specific problems in each basin (three forks, mainstem and tributaries) and projects intended to resolve those problems. The plan would include budgets, funding sources, organizational responsibilities and accountability, and milestones. 

Although the Watershed Management Board’s 2018–2023 Implementation Strategy, Regional Water Supply Planning Project, and Drainage-Based Management Project are steps in the right direction, none of them include all the elements necessary for basinwide success.

Phase 1 of the Regional Water Supply Planning Project had three major limitations. First, the project included not a single water-use efficiency project in any of the three sub-basins studied. Second, it failed to include any water-meter data in its baseline on out-of-stream (human) water uses, instead relying solely on estimates. Third, its forecasts of future water uses are inconsistent with the real world; the forecasts show substantial increases in water use, at variance with the historical record. 

To make matters worse, the work plan for Phase 2 calls for it to “rely on the methodologies developed during Phase 1.” The serious errors committed in Phase 1 will be propagated throughout Phase 2. We can and must do better!

— Contributed by Eric Hirst

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