Lake Ontario is a great lake with management context from International Joint Commission / Great Lakes-St. Lawrence regulation; USACE & ECCC monitoring. Lake Insights displays its latest available elevation from NOAA / U.S. Army Corps of Engineers (coordinated network).
Lake Status
0.16 feet below long-term average
−0.16 ft vs long-term average
- 7-day trend
- Falling
- 7-day change
- Down 0.49 ft
- 30-day change
- Down 0.94 ft
- Last updated
- 41 minutes ago
Lake Ontario is currently 0.16 feet below long-term average and has fallen slightly over the past week. Readings show levels trending lower over the past week while remaining below the long-term average.
Key Facts
Waterbody / project type
Datum
Current-level source
Why the level can change
General factors for Great Lakes
These are common influences for this type of lake. They do not identify the cause of a specific current change unless an operator update confirms it.
Basin water balance
Great Lakes levels respond to precipitation, runoff, evaporation, and connecting-channel flows across the basin.
Seasonal cycle
Levels typically rise in spring/early summer and fall later in the year, though the pattern varies by lake and year.
Connecting channels
Flows through connecting channels and regulated outlets influence how water moves through the Great Lakes system.
Wind & seiches
Strong winds can temporarily raise levels on one shore and lower them on another (wind setup / seiche).
Current data source
Managing authority: International Joint Commission / Great Lakes-St. Lawrence regulation; USACE & ECCC monitoring
Observation source used by Lake Insights: NOAA / U.S. Army Corps of Engineers (coordinated network)
Who manages the lake and who publishes the reading Lake Insights displays can differ. Lake Insights does not invent a source label from the managing authority alone.
General education
Shared background — not lake-specific facts
Lake Insights aggregates water level information from authoritative public sources such as the U.S. Army Corps of Engineers, NOAA, TVA, Bureau of Reclamation, power utilities, and other official lake operators. We preserve historical observations, calculate trends, and present lake conditions in a consistent format. For NOAA / U.S. Army Corps of Engineers (coordinated network), we link to the official source whenever it is available. Lake Insights does not predict future lake levels unless an official forecast has been published by the managing authority.
Common questions about Lake Ontario
- Who manages Lake Ontario?
- Lake Ontario is managed by International Joint Commission / Great Lakes-St. Lawrence regulation; USACE & ECCC monitoring. Lake Insights reports published gauge readings; it does not operate the waterbody.
- Where does Lake Insights get the level reading for Lake Ontario?
- Lake Insights displays the latest available elevation for Lake Ontario from NOAA / U.S. Army Corps of Engineers (coordinated network). The managing authority (International Joint Commission / Great Lakes-St. Lawrence regulation; USACE & ECCC monitoring) may differ from the agency that publishes the observation used on this page.
- What datum is used for Lake Ontario?
- Elevations for Lake Ontario are referenced to IGLD85 (MSL).