Scientists from the Washington Department of Ecology placed a pinkish-orange dye in the Pilchuck River as part of a study to help solve the water quality problems.

The Pilchuck River is considered a core summer salmonid habitat. This means their waters should not exceed 16°C measured as a 7-day average daily maximum value, and dissolved oxygen values should not be below 9.5°C. Oxygen dissolved in healthy water is vital for fish and aquatic life to "breathe” to survive.

Researcher Nuri Mathieu with Technician Paula Cracknell used “Rhodamine” dye that is somewhat fluorescent as part of their water quality monitoring. They released the dye at two locations, where Menzel Lake Rd. and 64th St. NE cross the Pilchuck River.

The dye will look pink- or rust-colored in the water before it dissipates downstream. This dye does not harm animals, fish, plants or people.

Researcher Nuri Mathieu from Ecology's environmental assessment program showed one of the sensors used in yesterday’s river water test. 10 sensors were placed 3 to 5 miles apart in this test and used to detect oxygen and temp plus 6 of those sensors also detect dye.

The video shows the dye release at Menzel Lake Rd. location.

The Pilchuck flows from the Cascade Mountains east of Granite Falls to Snohomish, where it joins the Snohomish River, which enters Puget Sound in Everett. The river currently fails to meet state clean water standards for temperature and oxygen content. Oxygen is critically important for fish. The river is also too warm. High water temperatures harm salmon, trout, and other aquatic life, and decrease the oxygen-carrying capacity of the water.

Water temperature influences what types of organisms can live in a water body. Cooler water can hold more dissolved oxygen that fish and other aquatic life need to breathe. Warmer water holds less dissolved oxygen. Many fish need cold, clean water to survive.

One way to cool water temperature is to shade the water body by adding or retaining streamside vegetation.
Data from the field work will be available next year, in advance of a full study that will guide Ecology and local governments' efforts to prepare a cleanup plan for the river. Rivers like the Pilchuck play an important role in restoring the health of Puget Sound and its troubled salmon runs.

For more information: http://www.ecy.wa.gov/