SEATTLE - Drivers on the State Route 520 floating bridge may have noticed workers on air boats spraying a bright blue-colored herbicide in the marshlands.
"The blue is a harmless dye that lets us see what plants we've sprayed and what we haven't," explained University of Washington gardener Neil Bonham as he guided us through a thick floating mat of plant life near the bridge.
He is looking for the signature yellow flower of the Garden Lossestrife, a non-native invasive plant that Bonham says has the potential to take over the entire fresh water marsh.
What they can't reach by boat, they have to hike to and the footing is nearly impossible. At one point, while trying to get close to one clump of the plant, I stepped into a hole in the mat and dropped waist deep into Lake Washington.
Bonham says it's difficult work and, while he hates to spray anything in the Arboretum, he says they are using the most ecologically sensitive aquatic herbicide they could find.
"Of course, other things will suffer, too, but we're trying to be as selective as we can," said Bonham.
With just one foreign invader having the potential to choke out thousands of native plants, Bonham said they can't afford to do nothing.