A watershed is an area of land that channels water to a nearby river or stream. There are many sizes of watersheds, from a single field and up. Iowa is part of the Mississippi River watershed, where every stream eventually empties into the Mississippi River, making it one of the largest watersheds in the world.
ACWA focuses on priority watersheds in Iowa that usually contain higher amounts of nutrients in the waterbodies. The Annual Water Monitoring Data page contains summaries of water sampling from priority Iowa rivers and tributaries.