Linn and Lane county grass seed farmers have constructed "grass waterways",  engineered waterways that can pass farm equipment in summer and fall when there is no runoff.  It's a way to drain sheet water from flat fields,   to ensure plants don't drown,  and not create impassable ditches.  

In response,  OSU  researchers sampled the runoff from those grass waterways when they were passing water,  sometimes a lot of it,  in the wet season.  They were looking for impacts on biology and the presence of pesticides,  fertilizers,  and other farm chemicals.

They found no chemical above any allowed limits,  and a surprising diversity of aquatic life,  and all of it native:   stream rearing chinook salmon and steelhead,  cutthroat trout,  amphibians,  all thought to be using the waterways as refuge from high water,  so to maintain their place in the river,  not be washed downstream.  Run up the waterway and hide out until the flood water goes away.  Turns out to be replacing lost habitat.