First of all I just want to say that I can’t belive my username is still in the system here, I haven’t posted in years.
So here’s my question.
I live in Milwaukee, WI. On my way to work I drive past Milwaukee’s stock piles of road salt. Just before winter they start getting their shipments in and they have sevral HUGE piles of salt and of course at the end of winter they are gone. I couln’t find exact numbers for how much they use each winter but it’s alot (I would guess somewhere in the area of 20,000 tons/year. Come spring as all the snow and ice and everything melt all the water goes down the storm sewers and all the storm sewers drain right into the lake. Why is it that with all the cities around Lake Michigan also salting their roads, and all that salt emptying into the lake, that the lake isn’t saltwater now? Is it just simply not enough salt to make a difference in such a huge body of water? Even so, it still seems like there would be some noticible difference in the water?
Well gee, the answer is sort of right in front of you. If all the winter salt being washed into the lake doesn’t make it taste salty then obviously there isn’t enough of it to do the job.
Lake Michigan has a surface area of 22300 sq. mi. and a mean depth of 276 ft. (Britannica) It thus contains 1166 cubic mi. of water. That much (approximately) fresh water weighs about 5.4 trillion tons. So 20000 tons is one ton of Milwaukee salt per each 267 million tons of Michigan water. Not even a drop in the bucket.
I don’t know the water to salt ratio in a brine that you can just barely taste. Maybe you can find it somewhere.
Well gee, the answer is sort of right in front of you. If all the winter salt being washed into the lake doesn’t make it taste salty then obviously there isn’t enough of it to do the job.
Lake Michigan has a surface area of 22300 sq. mi. and a mean depth of 276 ft. (*Britannica[/]) It thus contains 1166 cubic mi. of water. That much (approximately) fresh water weighs about 5.4 trillion tons. So 20000 tons is one ton of Milwaukee salt per each 267 million tons of Michigan water. Not even a drop in the bucket.
I don’t know the water to salt ratio in a brine that you can just barely taste. Maybe you can find it somewhere.
Lake Michigan has a volume of about 4900 km[sup]3[/sup]. That works out to 4.9 X 10 [sup]15[/sup] Liters of water.
According to the 2nd reference here , Milwaukee uses about 50,000 tons of salt a year.
50,000 tons of salt is about 4.5 X 10[sup]10[/sup] grams.
If all that salt were mixed into the lake you’d end up with 9.2 X 10[sup]-6[/sup] g/L, or a 9.2 X 10[sup]-7[/sup] percent salt solution.
It would take thousands of cities the size of Milwaukee to salinate the entire lake.
Well gee, the answer is sort of right in front of you. If all the winter salt being washed into the lake doesn’t make it taste salty then obviously there isn’t enough of it to do the job.
Lake Michigan has a surface area of 22300 sq. mi. and a mean depth of 276 ft. (Britannica) It thus contains 1166 cubic mi. of water. That much (approximately) fresh water weighs about 5.4 trillion tons. So 20000 tons is one ton of Milwaukee salt per each 267 million tons of Michigan water. Not even a drop in the bucket.
I don’t know the water to salt ratio in a brine that you can just barely taste. Maybe you can find it somewhere.
Well gee, the answer is sort of right in front of you. If all the winter salt being washed into the lake doesn’t make it taste salty then obviously there isn’t enough of it to do the job.
Lake Michigan has a surface area of 22300 sq. mi. and a mean depth of 276 ft. (Britannica) It thus contains 1166 cubic mi. of water. That much (approximately) fresh water weighs about 5.4 trillion tons. So 20000 tons is one ton of Milwaukee salt per each 267 million tons of Michigan water. Not even a drop in the bucket. However, I suspect that if you were to dip up some from close to a storm drain during a thaw it would taste salty. PS There are two places you shouldn’t do that: At home or someplace else.
Sea water, which is pretty salty, has about 1.5 lb of salt for every 62.4 lb. of water.
“It would take thousands of cities the size of Milwaukee to salinate the entire lake”
What about all the other cities that border the lake. Or, what about some smaller lakes with several big cities on them. (I can’t think of any off hand, but I’m sure there are some.
Of course you all realize that lakes empty their salinated water eventually into the ocean ? In fact, after millions of years, that is exactly how the final repository of salt , the oceans get it, from lakes and river.
Fortunately the river and land lakes are constantly replenished with fresh water.
It’d take ~48 billion tons of salt to get the lake up to about 0.9% (isotonic). That would require roughly ten years of salting by 98,000 cities as profligate in their salt usage as Milwaukee. There may be localized effects near each city, but not in the lake as a whole.
Lakes Mendota, Monona, Waubesa etc. in Madison would likely be in trouble if you dumped 50,000 tons of salt in them each year. Long before that happened though, I’d expect the citizens would complain about all their Oak trees dying.
Would somebody please take a bunch of my multiple posts out of here? When I tried to post I kept getting the “This page not available” screen. So I hit “Back” followed by “Submit” and again got “This page not available.” What a mess, ain’t modern technology grand?
I always wanted to know how so many multiple postings occured
According to the Britannica Michigan discharges 47000 cubic ft. per second into Lake Huron. That is about 10 cubic miles of water per year so the present flow through the lake would change water every 110 years. Far too frequently for the salt to build up to an amount that would make it taste salty.
All freshwater lakes have an outlet so their water is constantly changed. Lakes that don’t have one get salty over time. Great Salt Lake, the Dead Sea, the Aral Sea, the Caspian Sea are examples.