Snake River
Status: ORANGE ALERT
Length: 270 miles
Basin area: approximately 16,900 square miles
The Snake River is troubled by two major problems throughout its length in Oregon: toxic mercury and high water temperatures. The river also violates numerous other water quality standards according to the state of Idaho.
The Snake River is the 10th longest river system in the United States, extending over 1,000 miles from its headwaters in Yellowstone National Park, Wyoming, to its confluence with the Columbia River near Pasco, Washington. Oregon's Grande Ronde, Powder, Malheur and Owyhee rivers are tributaries of the Snake, and it is the Columbia River's largest tributary. About 270 miles of the river forms the border between Oregon and Idaho, where it flows through Hell's Canyon, one of the deepest gorges in the world. Hell's Canyon has been inhabited by Native Americans for the last 7,100 to 10,000 years, and the Nez Perce tribe maintains treaty rights to fish and other natural resources. Many competing demands are placed on the river, including agriculture irrigation, hydroelectric power generation, water-based recreation, and fish and wildlife habitat.
A Closer Look
Flow on the Snake River is heavily controlled by dams, distributing water volume more evenly throughout the year than would naturally occur. The dams impact water quality because pollutants accumulate in sediments behind dams (which can reduce pollutant concentrations downstream). They also impact water temperatures when slow moving water is warmed by the sun, and cool water gathers at the bottom of deep reservoirs.
The state has issued fish consumption advisories for the Snake River due to high concentrations of mercury in fish tissues. The primary sources of mercury are air deposition, legacy mining activities and natural geologic materials. Air deposition of mercury comes from cement plants, coal-fired power plants, and is blown in from places as far away as China. Reducing erosion can help control mercury that is transported to the river in sediment.
In addition to mercury and temperature, the state of Idaho lists the Hells Canyon portion of the Snake River, which borders Oregon, for bacteria, dissolved oxygen, nutrients, pH, sediment, DDT and dieldrin. In 2004, the two states developed a Total Maximum Daily Load (TMDL) for all these parameters except mercury. Practices in both states need to be managed in order for the river to achieve water quality standards.
Putting Nature to Work
In 2004, the Malheur County Soil and Water Conservation District partnered with landowners, local, county, state and federal organizations to create a 12.8-acre, 5-pond constructed wetland to filter the agricultural drain water from 850 acres of irrigated farm land. The five ponds were specially designed to filter sediment, nitrates, phosphates and bacteria from the agricultural drain water before returning it to the Malheur River. Monitoring has demonstrated that the constructed wetlands are effective at cleaning the water and will help achieve water quality targets in the Malheur and Snake rivers. In two years, the project treated an estimated 310 million gallons of water. In addition, wildlife such as migratory birds, quail, pheasants, mule deer and pelicans are making use of the new wetlands.
Malheur County landowners have been working for years to reduce the water quality impacts of agricultural drains. Due to the economic struggles today's farmers face and the limited availability of funding, only 5-10% of landowners in the county have been able to convert to more efficient sprinkler irrigation systems. While the cost of converting to a sprinkler system is about $700-1,200 per acre, the cost of installing the constructed wetland was $294.
per acre, creating a more cost-effective solution. The success of this project led the Malheur Soil and Water Conservation District to plan five other constructed wetlands in the Snake and Malheur basins, which are in varying stages of completion today. The constructed wetlands are a new best management practice for water quality in Eastern Oregon.
When the Malheur County Soil and Water Conservation District constructed a wetland to improve water quality from agricultural drains, they found that it provided additional environmental benefits. Within weeks of its initial filling, pelicans began using the new wetland. © Malheur County Soil and Water Conservation District
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