Although NOAA is known for its work in marine habitats, our agency also monitors, studies, and protects many freshwater resources. NOAA satellites monitor the planet’s water supply, by mapping snow and ice fields and helping scientists predict where, when, and how much water will be available for humans to use. NOAA hydrologists provide river level forecasts to protect life and property and manage navigability of waterways. Many important fishes like salmon and sturgeon are anadromous, traveling between freshwater and saltwater throughout their life cycles. NOAA monitors and manages these fishes in partnership with local agencies. The Great Lakes, sometimes called our "third coast," are the foundation of a major coastal ecosystem. Though the lakes are freshwater, many of NOAA’s marine programs serve the region, including Marine Debris, National Marine Sanctuaries, Fisheries, The National Estuarine Research Reserve System, and others.
The Great Lakes system offsite link includes five large lakes, one small lake, four connecting channels, and the St. Lawrence Seaway. The large lakes are Superior, Michigan, Huron, Erie, and Ontario. They hold about 90% of the freshwater in the United States and approximately 20% of the world's freshwater supply. Forty million residents of the United States and Canada depend on this system for clean drinking water.
