On several sunny, still days over the last two months a Cessna 182 flew low over the Yakima River in Washington state, looping back and forth along the river's twisty course.

In the tiny aircraft Robert Mueller, a senior research scientist for Pacific Northwest National Laboratory in Richland, kept his eyes focused on the river, looking for patches of light colored rocks where salmon had spawned this fall. In promising areas Bergstrom pilot Don Clayhold would circle around, helping Mueller get an accurate count of salmon redds, or nests, from the Highway 240 bridge in Richland up the river to Union Gap.

A check for salmon redds from the air would not have been possible a decade ago, but now improved water quality in the Yakima River allows the redds to show up as light spots. Its goal is to combine new and existing data on salmon in the lower Yakima River to identify projects that could improve salmon runs in the near term, like planting more vegetation along the river. Such small projects could be done while work continues to address big issues in the Yakima River, such as water allocation for both irrigation and salmon recovery.

Read the full story at tri-cityherald.com.com.