The Nisqually watershed covers 460,172 acres within Lewis, Pierce, and Thurston counties. The river flows from the foothills of the Cascades to the Nisqually National Wildlife Refuge. Precipitation averages 35 to 60 inches annually in the lower agricultural areas, but can be much higher near Mount Rainier, which sometimes receives over 100 inches in a year. Most precipitation falls in the winter, leaving streams dependent on groundwater in the summer.
The Nisqually Delta, where the river meets the waters of Puget Sound, is made up of salt marsh and mudflats. Forestry is the primary use in the Nisqually basin, but agriculture is also well represented. The lower Nisqually is one of the most heavily farmed areas in the western part of the state.
- Counties: Lewis, Pierce, Thurston
- National Estuary Programs: Puget Sound
- Other Watersheds Upstream: None
- Other Watersheds Downstream: Puget Sound