When environmental conditions are optimal, waste organic compounds are rapidly decomposed, and accumulated heavy metals and phosphorus are buried in deep sediments.
Wetlands remove sediments and toxic substances, and remove or filter excess nutrients.
These wetlands improve water quality just as a water treatment plant costing millions of dollars to build and operate could. In Texas the water quality of some rivers, streams, and bayous has been degraded due to runoff from surrounding lands. Wetlands along these waterways provide a buffer that filters much of this runoff.