Malheur River

Ontario, Oregon

THIS SITE KNOWN TO CONTAIN DANGEOUS LEVELS OF SEDIMENT AND NITRATE. DO NOT SWIM OR EXPOSE CHILDREN TO WATER UNLESS FLAGGED GREEN.

The Malheur River (local pronunciation: "MAL-hyure") is a 190-mile-long (306 km) tributary of the Snake River in eastern Oregon in the United States. It drains a high desert area, between the Harney Basin and the Blue Mountains and the Snake. Despite the similarity of name, the river does not flow into nearby Malheur Lake, which is located in the enclosed Harney Basin southwest of the watershed of the river. When water levels were higher, Malheur Lake would drain into the Malheur River.

The lower Malheur River is used for irrigation in the agricultural potato-growing in the Snake River Plain along the Idaho-Oregon border. There are approximately 370 miles (600 km) of irrigation-related canals and ditches in the lower basin of the Malheur River and its tributary Willow Creek. The streamflow of the Malheur and its tributaries is heavily influenced by a complex system of irrigation diversions, siphons, and canals, which begin near Malheur river mile 65, near Namorf and Harper, Oregon. This irrigation system extends downstream to the mouth of the Malheur at Ontario, Oregon.

WATER QUALITY

Failed to meet water quality standards
Special Status
This status is based on the latest sample, taken on . Snake River Waterkeeper updates the status of this beach as soon as test results become available. These results were posted to Swim Guide on at

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CURRENT WEATHER

2°C

Clear and sunny

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MONITORING FREQUENCY

SOURCE INFORMATION

As part of its Water Quality Program, Snake River Waterkeeper monitors water quality at more than 100 sites on the Snake River and its tributaries for temperature, dissolved oxygen, pH, salinity/conductivity/total dissolved solids, ammonia, and nitrates. Data are collected at sample sites June-October and assigned safety ratings based on comparison to EPA's Recreational Water Quality Criteria for Human Health:

pH: 5 – 9 µg/L
Salinity/Conductivity/Total Dissolved Solids: 500 mg/L
Nitrates: 10 mg/L

A site is marked Green when single sample results meet all Human Health Criteria.
A site is marked Red when the results are equal to or above Human Health Criteria.
A site is marked Grey when there are no current results or no available information.
Sites found to exceed EPA's Aquatic Health Criteria are noted in site descriptions.

While criteria measured are useful indicators of contamination, there are many other potential sources of pollution that are not reflected in our Swim Guide, including E.coli and other bacteria, heavy metals, pharmaceuticals, fertilizers, and pesticides that harm aquatic life.

Download the free app for smartphone and learn about Swim Guide 3.0 at www.theswimguide.org. To learn more about our efforts to protect and restore the Snake River's water quality, visit www.snakeriverwaterkeeper.org.

WATER QUALITY GRAPH