Department of Ecology News Release - July 21, 2015

Researchers to test Sammamish River water with dye
Teams will conduct two days of intensive monitoring

REDMOND – Scientists from the Department of Ecology will place a pinkish dye in the Sammamish River as part of a study to help solve the stream’s water quality problems. The river fails to meet state clean water standards for temperature and oxygen content.

The tests will begin on July 27. The river flows from Lake Sammamish in Redmond to Lake Washington in Kenmore. Lake Washington empties into Puget Sound.

The dye is non-toxic

The researchers will use “Rhodamine” dye that is somewhat fluorescent. They will release the dye where the river flows under NE Marymoor Way at dusk on July 27, and on other dates if needed. The dye will look pink- or rust-colored in the water before it dissipates downstream. It does not harm animals, fish, plants, or people.

“You needn’t worry if you see a slight pink or tan tint in the water,” said Ralph Svrjcek (pron: SVER-chek) of Ecology’s water quality program, who is coordinating the study.

“This dye is commonly used for this type of scientific study,” said Svrjcek. “Research has shown it has no effect at all on human health or aquatic life at the very low concentrations we use.”

Researchers will collect river data

Scientists will track the dye plume with a fluorometer, which detects the small amount of dye in the stream, even after it is no longer visible. They will take measurements at several downstream locations.

Over the following two days, a team of eight Ecology researchers will collect samples of river water and use electronic probes to gather data on the stream. They will collect information on temperature, flow, dissolved oxygen and nutrients in the Sammamish and its tributaries.

The river does not meet clean water standards

There isn’t enough oxygen in stretches of the Sammamish, causing it to fail state clean-water standards for 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.

“These tests and samples will help us understand river conditions and how long water takes to travel down the river,” said Teizeen Mohamedali, an environmental engineer with Ecology’s Environmental Assessment Program. “The information will help calibrate and validate a water-quality computer model that we will use to analyze temperature and dissolved oxygen during critical summer conditions.”

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 Sammamish play an important role in restoring the health of Puget Sound and its troubled salmon runs.


Larry Altose, communications,, 425-649-7009, @EcySeattle

Ralph Svrjcek, Water Quality Program,, 425-649-7165

Teizeen Mohamedali, Environmental Assessment Program,, 360-715-5209