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|May 06, 2017 Post 85|
why is the lake so high?
Not surprisingly many folks are blaming the IJC for the high water eating up yards and marinas and other bay front property. The neighborhood beach and bluff near my house is contributing many tons of gravel and sand to the 'downstream' beaches- could be four foot erosion recession this season. (The long term average is 2 to 3 feet at our location)
So whose “fault” is this? I would submit that this is the wrong question to ask. Let's try to understand the natural and unnatural processes at work here.
First, obviously there's a lot of water around. Locally in Lake Ontario's watershed we have had a lot of rain, possibly more than twice the normal amount basinwide. At Rochester total rainfall for March and April through the 25th was 8.78 inches ( and it was raining when I wrote this on 4-25). The normal total for March and all of April is 4.70.
According to NOAA funded research from the University of Michigan, overall precipitation throughout the Great Lakes region has increased 11% since 1900. This is in keeping with climate change model predictions – average temperatures in the region have gone up 2.0 degrees F. Warmer air can hold more water so extreme precipitation events are more likely. In fact since 1958 the number of such events and flooding has gone up 37% in the Great Lakes basin.
Warmer moist air also helps fuel more severe storms. This in turn creates more wave action that then can erode and damage shorelines. Though worse along the open lake shore, when combined with high water, wave action can also erode shorelines of the protected bays.
Second, the great global warm up has moved up the date of snow pack melt. Snow melt upstream from Lake Ontario raises the levels of Superior, Huron and Michigan. Runoff from these lakes can and does raise the level of Lake Ontario. Historically our lake peaked in water level in early summer.
As more precipitation falls as rain rather than snow, it looks like we are peaking earlier than the historic June timing of the past. Of course, the probability of strong north winds in April is a lot higher than in June and more wind means more waves and more erosion damage.
Ice cover also impacts the rate of shoreline erosion and sediment transport dynamics on the open lake. Anchor ice that forms along the shore acts as a winter time 'sea wall' of sorts and protects the open lake shore from wave action and undercutting. Recent ice cover trends are mixed, but since 1973 average ice cover has declined 71%
While extreme and overall precipitation trends in the Great Lakes basin are pretty clear, the evidence for more powerful and frequent wind storms is not as well defined. Some studies show an increase in high winds, others don't. One study done about 20 years ago found that strong cyclones with central pressures of 992 hPa more than doubled in frequency in the US Great Lakes region from 1900 to 1990. (Deeper lows cause stronger winds).
Another study suggests that there has been an increase in the number of November and December storms – typically a time of lower seasonal water levels and less damage in the bays. It's too soon to tell if we are seeing an increase in late winter early spring storms, but I'd guess if we keep amping up the Green House Gases it's a pretty fair bet.
Lake Ontario has a downstream dam that regulates flow through the lake. However, the dam operators have to consider downstream flooding as they increase releases from the lake. Recently the Ottawa River that dumps in to the St. Lawrence at Montreal has also been running very high. Streams that drain the Adirondacks are also contributing and at least one Quebec town has already had an evacuation just west of Montreal because of flooding.
CBC story dated 22 April quoted one area resident from Blainville Quebec “It's really shocking, we don't really know what to think, I've never seen this in 20 years — it's quite big."
The Army Corps projections for the lake levels show us still about five inches below the Hurricane Agnes level of 1973, but they also show us coming up some more.
Back in 1973 when I watched the pollywogs swimming around the PYC parking area in front of our Lightning, the bays were not nearly as developed with mega mansions and 3000 square foot cottages. Back then a lot of people had little “camps” perched on railroad ties and cinder blocks above the ground. If we do get up to the Hurricane Agnes level again, you can expect the tax payers are going to be shelling out for a lot of big boulders again, just as we did back then. I surely hope it will not happen but climate change and Mother Nature are batting last in this game. And at some point the tax payers are going to be tapped out.
Is it time to think about that foundation of Indigenous Law? Responsibilities and respect rather than “Rights?” Humans have historically succeeded by being adaptable- can we continue to change our ways?