Intervention needed to improve river health in Tricity

Sub Levels

Outsiders in the Tri-Cities often see arid landscapes populated by green life only where human hands have touched the earth. Locals also see the desert environment. However, many consider themselves inhabitants of the river world. Two large rivers meet south of Pasco, and the important river Yakima flows into the Columbia River between Kennewick and Richland.

This identity is reflected in the convention center, nicknamed Three Rivers. A community treasure trove, the 3 Rivers Community Foundation, has adopted the same name. Many other organizations and companies have appropriated the description for their names.

But not all is well for the ribbon of life that forms the identity of the Tri-Cities. This can be seen in the attached Benton-Franklin trend graph “Overall Water Quality Index”. The Index (WQI), created by the Washington State Department of Ecology, combines several characteristics of healthy surface water and summarizes the scores into a unitless (index) set of numbers.

Components include turbidity, temperature, phosphorus (pH) levels, fecal coliform counts, dissolved oxygen readings, and more. The components are sampled monthly, the data are transformed into subindexes, and the subindex areas are combined to produce annual averages. 100 is the maximum score. A reading above 80 rates the water quality as ‘good’ or meeting expectations. A WQI reading of 40-79 indicates that the department has some concerns. A score below 40 indicates that the water body is of ‘most concern’.

As you can see, Columbia (Umatilla) and Snake (Pasco) currently score within the ‘meets expectations’ range. The two had 2021 WQI readings of 85 and 81 respectively. However, the same assessment does not apply to Kiona’s Yakima River at this time. Her WQI reading for 2021 was 44, almost in the red, or “greatest concern” zone.

Courtesy of Benton Franklin

plummeting quality

Importantly, the Yakima River WQI has recently plummeted. The average score in 2019 was 61. In two years its quality has dropped by nearly a third of his. What’s behind this dramatic decline? Rising temperatures.

The WQI temperature is 54 in 2020 and 32 in 2021, according to detailed corroboration by the provincial Ministry of Ecology. At this level the water is simply too warm for the health of river flora and fauna.

In particular, warming is a downstream problem. The same-year river measurements for the Cle Elum River and Nob Hill (Yakima) were generally within the “expected” range.

The Lin WQI subindex for the Yakima River in Kiona has also flashed yellow in the last two years, with a value of 50 for both years. Phosphorus promotes algae and plant growth and is harmful to both vertebrates and invertebrates. Sources include not only the underlying geology of the river bed, but also effluent from sewage treatment plants, lawns and fields, failure of purification systems, and effluent from fertilizer storage areas.

Like temperature, high pH values ​​are also a downstream phenomenon. In river readings taken at Cle Ellum and Nob Hill, Lynn’s WQI sub-index values ​​were all above 90.

The water quality of the Yakima River has been declining recently, but the water quality is declining in the long term. As the trend graph shows, the WQI value in Kiona in 2000 was 65. By 2019, the WQI had dropped to 61, despite years of concerted efforts by state and local authorities to improve quality levels.

downward trend

It is worth noting that the water quality of the other two rivers has also declined over the same 20 years. Pasco’s Snake River water quality was about the same in 2021 and he was in 2000. However, the water quality of the Columbia River dropped from 94 to 85 over the same period.

What can be done to stop the decline, especially in Yakima? Restoration efforts are still underway and could fill an entire issue of this document. Some (most?) of water quality deterioration is due to human intervention. Therefore, policies to increase water constituents such as phosphorus, dissolved oxygen and faecal coliforms are likely to move the needle, albeit slowly.

Temperature imposes even more difficult demands. Rising temperatures across the Northwest Interior do not bode well for traditional life in all waters. But even here, some steps like maintaining flow and shading strategies could bring improvements to Yakima. Let’s hope that over the next decade, this iconic river trend line will at least recover to its previous level. Could it be possible to approach two larger adjacent water bodies as well?

Patrick Jones is Executive Director of the Institute for Public Policy and Economic Analysis at Eastern Washington University. The Institute’s project, Benton-Franklin Trends, uses local, state, and federal data to measure the economy, education, and civic life in Benton and Franklin counties.

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