Watershed Plans

Desired Trend


Current Trend

Baseline (2010): 8
Current (2021): 31

Theme Green


Number of watersheds with a plan or active organization

Why is it Important?

Everyone lives in a watershed. A watershed is the area of land where runoff drains to a particular stream, river, wetland, or other body of water. There are nine major watersheds in the St. Louis region that drain to major rivers such as the Mississippi, Missouri, Meramec, or Kaskaskia Rivers, and many smaller watersheds located within those that drain to smaller creeks and streams. Healthy watersheds are necessary for protecting water quality. Watershed plans focus on improving water quality by identifying pollutants and developing strategies to control pollutants. Sources of pollution that may be addressed by watershed plans include urban runoff, agricultural runoff, construction runoff, and erosion. This indicator measures the number of watershed plans or active organizations that promote the health of a watershed in the St. Louis region.1

How are we Doing?

The number of watersheds with a known plan or active organization increased from eight in the baseline year 2010 to 31 in 2021. Currently, 50 percent of the land in the St. Louis region is covered by a plan. Additionally, 26 percent is covered by an organization that does not have a plan but is focused on the watershed. Many of the plans and organizations span a wide area and do not provide as much detailed analysis or guidance as plans that address smaller watersheds. The most recent updates to watershed activity in the region includes a new plan for Wood River in 2020, an updated plan for Piasa Creek in 2020, and a new group working in the Prairie du Pont and Judy's Branch creeks in 2021.

Geographic Level

St. Louis eight-county bi-state region, including Franklin, Jefferson, St. Charles, and St. Louis counties and the city of St. Louis in Missouri and Madison, Monroe, and St. Clair counties in Illinois. View map.


1Watersheds are identified using Hydrologic Unit Codes (HUCs) delineated by the United States Geological Survey (USGS) based on where surface water drains. There are six levels of hydrologic units. Each unit is identified by a unique HUC, which consists of two to twelve digits depending on which of the six levels is being defined. Each point in the landscape is located within multiple nested watersheds (one for each of the six levels), ranging from sub-watersheds up to subregions and regions.  In the St. Louis region, watershed plans and organizations sometimes use the HUC system to delineate a watershed for their work but some plans and organizations consider other factors to draw the boundary for their work. Therefore, this indicator relies on each plan or organization’s watershed delineation to determine the number of watersheds addressed. Some of the watersheds counted in the indicator overlap or are nested within each other. To provide a fuller picture of the extent of watershed planning in the region, statistics on overall coverage of the region’s land with watershed plans or organizations is also provided.