A new state report shows the extent of metals, pesticides and other pollutants found in water, sediment and fish tissue samples taken from 17 rivers and streams across Northeastern Oregon, including the Powder and Burnt rivers in Baker County.

The report from the Oregon Department of Environmental Quality (DEQ) compiles results from samples collected in 2011, 2012 and 2016.

Overall, the agency tested 111 water samples from 29 sites, 21 sediment samples and seven tissue samples from smallmouth bass and crayfish.

Although tests detected contaminants such as arsenic, mercury, pesticides and DDT (an insecticide banned in the U.S. in 1972), “none of the chemicals were found at levels that would pose an immediate threat to public health,” according to DEQ. “This means the area’s rivers and streams continue to be safe for recreation and other users.”

The report covers the Powder, John Day, Grande Ronde and Walla Walla river basins. The report is available online at https://www.oregon.gov/deq/wq/Documents/wqm-NEbasinsummary.pdf

Sampling locations in Baker County:

• Powder River at Highway 86 between Baker City and Richland.

• North Powder River near North Powder.

• Powder River near Hudspeth Lane in Sumpter Valley.

• Burnt River at Snake River Road.

• Burnt River just upstream of Huntington waste treatment plant outflow (this sampling site is less than 100 meters from the other Burnt River location).

• Powder River at Snake River Road near Richland.

The sampling site with the highest number of pollutants is the Burnt River upstream from the Huntington waste treatment plant outflow.

Water samples collected there contained 15 metals, the most of any of the sampling sites in the region, according to DEQ.

Concentrations of five of those metals exceeded DEQ standards, according to the report — aluminum, inorganic arsenic, iron, selenium and thallium.

The Burnt River water samples also contained DDT at levels exceeding DEQ human health criteria and freshwater aquatic life criteria.

Samples of crayfish tissue at the Burnt River site also had the highest concentration of arsenic among testing sites.

However, the human health criteria are based on consumption amounts — of fish and untreated water — so high as to be unrealistic, so the concentrations of toxins in fish and shellfish, and in the water, are not considered immediate risks to human health, said Laura Gleim, public affairs specialist for DEQ’s Eastern Region.

The human health criteria assume people are eating at least 23 meals, of eight ounces each, of fish or shellfish each month from the Burnt River, or drinking untreated water from the river in large quantities, up to two liters per day, regularly over a long period, Gleim said.

Across the region, mercury is the metal most often found in samples of fish and shellfish tissue.

The state has consumption guidelines for fish and shellfish based on mercury concentrations.

Other findings in the DEQ report:

Ammonia concentrations

Concentrations exceeded the DEQ criteria for freshwater aquatic life at two sites — the North Powder River near North Powder, and Prairie Creek at Enterprise.

Arsenic and iron concentrations

Concentrations of arsenic, a toxic element which is often associated with mining, were above the “background concentration” at two sites — Clear Creek near the Red Boy Mine west of Granite, and the Powder River near Hudspeth Lane in Sumpter Valley, just upstream from Phillips Reservoir.

Both sites are in areas that were extensively mined.

Iron concentrations were above background levels on the West Prong of the Little Walla Walla River and the Little Walla Walla River.

In the case of both arsenic and iron, “elevation over these background concentrations does not indicate a potential health risk to humans or aquatic life, only that the concentration detected is higher than the concentration regularly detected in sediment across the region,” according to DEQ. “Concentrations above the background concentrations may indicate an anthropogenic input of the metal.”

Combustion byproducts

These include polycyclic aromatic hydrocarbons (PAHs) and related compounds associated with the incomplete combustion of organic matter from automobiles, fossil fuel burning, woodstoves and cigarette smoke, for example.

They can pollute water by falling from the air or in water runoff from roads, parking lots and other hard surfaces.

Tests of water samples from two sites detected combustion byproducts.

One substance, dibenzofuran, was found in Prairie Creek at Enterprise.

Five separate compounds were found in water at the Burnt River site upstream of the Huntington water treatment plant.

Dibenzofuran does not have a set limit for concentration, while the other compounds detected in the Burnt River sample did not exceed criteria.

Current-use pesticides

Water samples were tested for glyphosate (Round Up)and its breakdown product, as well as many other chemicals that can enter water from the air, surface runoff and from fields forests, lawns and roadside spraying.

The larges number of pesticides (five) were found in water from the Grande Ronde River at Peach Lane.

The complete Northeast River Basin Toxics Monitoring report is available online at the Oregon Department of Environmental Quality website.

https://www.oregon.gov/deq/wq/Documents/wqm-NEbasinsummary.pdf