At precisely 9:30 a.m., James Kardouni and Sara Livingston stood in the middle of the Snoqualmie River, just upstream from the bridge where state Route 202 crosses overhead in Fall City.

They opened two plastic containers, upended the contents into the water, then washed out the containers as the river turned bright pink around them. The stain quickly washed under the bridge, fading into a rust-red splotch as it was diluted in the water and spread downstream.

Kardouni and Livingston are both environmental specialists with the state Department of Ecology, and their work Aug. 15 – releasing a nontoxic dye into the river – was a small part of a larger project to analyze the temperature of the Snoqualmie River watershed.

Farther downstream, the Rhodamine dye will be invisible. But at two points, located seven and 13 miles from the release site, a measuring device called a Hydrolab will be able to detect it. From its readings, researchers will get a picture of how quickly the river is flowing at that point.

Temperature is one of the most important factors in determining a stream’s health, and slower-flowing streams tend to heat up more. Understanding more about the Snoqualmie watershed will help the department better manage the streams and the fish, especially salmon, that depend on them.

“Here in the Pacific Northwest, a healthy stream is a cold stream,” said Ralph Svrjcek, a water cleanup specialist with the Department of Ecology.

The Chinook salmon population is at 6 percent of historical levels, Svrjcek said. The state would like to see those numbers go back up again.

Kardouni and Livingston were in and out of the water in less than half an hour. Livingston paused to collect discarded beer cans and other trash from the beach before they headed back to the office.

The two researchers dropped the dye into the Bear/Evans Creek system two weeks ago, and last week they released the dye into the Snoqualmie in five locations to measure along a 60-mile stretch from the edge of the Mount Baker-Snoqualmie National Forest in the Cascades down to the confluence of the Snoqualmie and Skykomish rivers.

The dye is not toxic to fish, plants or people, although it can stain clothing or skin -Kardouni’s hands were covered with pink splotches after the release.

The appearance of the river turning orange might be alarming to those who don’t know what’s happening, Kardouni said. A release into the river upstream from Duvall’s McCormick Park on Aug. 14 nearly caught some swimmers by surprise, but they were warned and got out of the water before the dye patch reached them.

For years, water temperatures have been higher than normal. Readings taken in 2004, for example, showed temperatures of 24 degrees Celsius, or 75.2 degrees Fahrenheit, both above Snoqualmie Falls and at the Crescent Lake Tualco Road bridge in Snohomish County, Kardouni said.

Those readings were one of the reasons why the study was launched to look at the watershed on a broader basis. The optimal temperature is 18 degrees Celsius, or 64.4 degrees Fahrenheit, Svrjcek said.

If a stream is too warm, then fish will suffer, becoming more susceptible to disease, and juvenile fish might have developmental problems, Svrjcek said.

Water temperature stations are also continuously collecting data at 40 different locations along the river. Other measurements in the watershed will look at water volume and other criteria as part of the broader study.

The river can be too warm for many reasons, but one of the prime suspects is simply that too much vegetation has been cleared around the river’s tributaries, such as the Raging River and Patterson Creek.

“Probably the best tools against these high temperatures are trees,” Svrjcek said.

Because those tributaries often cross private property, particularly agricultural land, the state will have to work extensively with those landowners and local businesses on restoration efforts. By itself, the study does not have the force of regulation, Svrjcek said.

Clearing as a result of spreading development also can be a culprit, and river views tend to increase the value of real estate.

“One person doing it is not the problem. It’s many people doing it,” Svrjcek said.