Many saprophytic fungi can help clean up contaminated water.
This can be done by filling a trench with inoculated substrate
(for example, burlap sacks filled with straw) in an area that
contaminated water will have to flow through, for example, downhill of a farm.
Pleurotus and Coprinus species and other species on the market list can filter water well.
Some mushrooms accumulate heavy metals and therefore should be picked with caution.