Weekly Lake Ontario update

Lake Ontario water levels dropped more than 1.5 inches between June 26 and July 4, as outflows through the Moses-Saunders Power Dam remained at record highs and the net total supply of water entering the lake declined. The lake remains more than 32 inches above average for this time of year. The above graphic shows water levels, inflows and outflows for various points along the Lake Ontario-St. Lawrence River system.

OSWEGO — Lake Ontario water levels fell more than two inches in recent weeks since peaking several times from early- to mid-June.

Water levels first peaked June 6 at 249.08 feet and remained above 249 feet throughout the month of June, equaling the high water mark on three other occasions, before finally dipping below 249 feet July 1. Lake Ontario water levels continued to decline throughout the week, dropping to 248.91 feet on July 4.

The 249.91 feet water level is 32.16 inches higher than Lake Ontario’s average level for this time of year.

International regulators, who earlier expected lake levels to stabilize and potentially start to decline in early June, are calling the recent drop a positive sign and believe the worst could be behind lakeshore municipalities and property owners.

The International Lake Ontario-St. Lawrence River Board (ILOSLRB), which regulates outflows from Lake Ontario through the Moses-Saunders Dam, tracks water levels in several areas of the Lake Ontario-St. Lawrence system, and the most recent data shows water levels declining in all four areas measured — Lake Ontario, Lake St. Lawrence, Lake St. Louis and Montreal Harbor.

“The board expects that the water levels will continue declining and the high water crest is behind us as we look forward to the rest of the summer,” ILOSLRB U.S. Section Secretary Bryce Carmichael said in a statement Friday.

Carmichael noted the water level on Lake Ontario decreased about 1.6 inches between June 26 and Jul 4.

Oswego Mayor Billy Barlow appeared cautiously optimistic about the receding water levels Friday, noting if the current trend continues the city could reopen Wright’s Landing Marina, which was closed May 30 due to flooding, later this summer.

“It definitely has gone down a bit in the last week,” the mayor said of the Lake Ontario water levels. “Hopefully we continue getting dry weather and the IJC can continue high outflows so the water continues to go down.”

Barlow said with a relatively dry forecast, officials are hopeful lake levels continue to drop enough for the city to reopen the boat launch late next week. Barlow noted prior to reopening the city Department of Public Works would have to clean up the area when the water recedes.

Outflows through the Moses-Saunders Dam have been maintained at or near record high levels of 367,300 cubic feet per second (cfs) since mid-June, according to ILOSLRB data. The net total supply of water entering Lake Ontario has dropped to around 321,000 cfs, far below the 431,200 cfs highs of mid-April and 390,900 cfs in late June.

The amount of water entering Lake Ontario through Lake Erie, which makes up roughly 85 percent of the net total supply, remains high, but Ottawa River outflows have fallen from a peak of 325,500 cfs on April 30 to less than 90,000 cfs in early July. 

Lake Ontario water level forecasts from ILOSLRB, which are based on historical water supply conditions from 1900 to 2008, indicate under average conditions the lake would fall below 248 feet by mid-August.

Shoreline property owners and elected officials have blamed the International Joint Commission (IJC) — the bi-national body that oversees shared U.S.-Canadian waterways — and the Lake Ontario water management strategy the organization adopted in 2016, known as Plan 2014.  

The IJC, however, maintains heavy rainfall and snowmelt in recent years has brought more water into the lake than the Moses-Saunders Dam can release without flooding communities along the St. Lawrence River, which also experienced flooding in 2019.

Lake Ontario reached a record high of 248.05 feet in May 2017, following the adoption of Plan 2014. Two years later the record was surpassed when the lake reached 248.98 on May 31 before continuing to rise.

Local governments and residents have called on the IJC to suspend Plan 2014 and return to the previous water management document, known as Plan1958-D, while an updated plan is considered.

Plan 2014 was adopted by the IJC in 2016 and designed to protect against extreme water levels, restore wetlands and prepare for climate change. The IJC said the plan would return "more natural variations of water levels" to Lake Ontario and the St. Lawrence River to restore ecosystem health.

U.S. and Canadian commissioners said no water management plan could have prevented flooding this year.

IJC commissioners recently promised to review Plan 2014, but noted it was developed over 16 years and involved an extensive review of alternative plans, scientific study and public engagement.

Commissioners said a review would not likely be complete before the end of 2019.

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