We've made some changes to EPA.gov. If the information you are looking for is not here, you may be able to find it on the EPA Web Archive or the January 19, 2017 Web Snapshot.

Geophysical Lake Ontario

Map of Lake Ontario

  • second smallest by volume
  • average depth 283 ft. (86m)
  • retention time = 6 years (a measure based on the volume of water in the lake and the mean rate of outflow)
  • urban industrial centers (Hamilton and Toronto) on the Canadian side
  • U.S. shore is less urbanized, not intensively farmed

Lake Ontario map from the National Oceanic and Atmospheric Administration