Ludwigia, an aquatic plant that originates from South America, has become an invasive pest in the creeks and Laguna de Santa Rosa, a large seasonal wetland that is a nesting area for migrating birds. Sonoma County citizens work hard to protect the health of the Laguna and the creeks that supply it. Ludwigia was probably introduced by tropical fish fanciers who carelessly flushed this decorative plant into the creek. Like so many plants, it grows vigorously here, mainly along shallow areas of the Laguna’s main channel and tributary creeks.

Piner Creek, which runs behind our house, has an open, sunny spot where ducks raise their young and children like to throw bits of bread from the nearby bridge. Larger migratory birds like egrets sometimes fish here because there are lots of small fish.

Ludwigia anchors is roots in the mud at the waterline and grows large mats that cover the surface of the water, preventing the fish from getting insects and preventing birds from fishing. Ludwigia appeared for the first time this spring and by Labor Day had covered almost all of the surface of the creek behind our house. Saturday, Howard and I hauled out several sacks of it.

A about a half-mile farther down Piner Creek, it merges with Paulin Creek and this is a prime fishing area for birds. It is a beautiful spot and it was starting to become choked with Ludwigia also, so Sunday morning I went down there by myself to clean it up. I gathered up two bags of weeks but hurt my back and had to ask a passing jogger to help me haul the second bag up the creek. The next morning, Labor Day, it looked like much of the Ludwigia had grown back! (see photo left above)

Monday evening, Howard helped me haul up another four bags of weeds (see photo right above). Let’s see how long this cleanup lasts. We may have to resort to some targeted herbicide along the damp soil at the waterline.

Piner Creek is supposed to be part of the steelhead hatchery system, but Ludwigiacreates a barrier to migrating steelhead and other fish, and its bacterial decomposition threatens oxygen-dependent wildlife in the water. The Laguna Foundation is working with USDA-ARS researchers and local agencies to find a long-term solution to the problem.