Understanding Our Watersheds
Explore how watersheds work, why they matter, and how SEAWA helps protect them.
Definition
A watershed is an area of land where rainfall and snowmelt drain into a common water body like a river, lake, or wetland. Water flows downhill through streams and rivulets, eventually reaching larger bodies of water.
Smaller watersheds can combine to form larger basins (catchments or hydrologic units). Watersheds are defined by topography, with higher elevations separating different drainage areas. For example, the Rocky Mountains divide the Pacific and Atlantic watersheds in North America.
Some watersheds, called endorheic basins (like Pakowki Lake), retain water without outflows to other basins.
Why It Matters
Watersheds sustain clean water, healthy ecosystems, and resilient communities. They collect and channel rainfall and snowmelt for drinking water, agriculture, and wildlife—while filtering pollutants, recharging groundwater, and reducing flood and drought risk.
What we do on the land affects water quality for communities downstream.
Groundwater and surface water are closely connected; impacts to one often affect the other.
Protecting watersheds protects the land, water, and life that depend on them—including our communities.
In short: healthy watersheds are essential infrastructure for clean water and regional resilience.
Explore SEAWA’s Region
Dive into SEAWA’s watershed map to see the full basin, or zoom into Local sub-watersheds or "pocket watersheds" to understand how creeks, coulees, and wetlands connect to the larger system.
View SEAWA’s watershed areas, learn how water moves across the region, and explore local watershed pages with maps, projects, and data.
Zoom into smaller “Local sub-watersheds” to see how local creeks, wetlands, and coulees contribute to the broader SEAWA watershed.
Stay Informed
Current conditions, advisories, and seasonal trends for the SEAWA region’s rivers, lakes, and groundwater.
