Yes and no. :)
I didn't believe the falls could freeze, had to take a look-see.
The tremendous volume of water never stops flowing, However, the falling
water and mist create ice formations along the banks of the falls and river.
This can result in mounds of ice as thick as fifty feet. If the Winter is cold for
long enough, the ice will completely stretch across the river and form what
is known as the "ice bridge". This ice bridge can extend for several miles
down river until it reaches the area known as the lower rapids.
Until 1912,visitors were allowed to actually walk out on the ice bridge and
view the Falls from below. February 24th of 1888 the local newspaper
reported that at least 20,000 people watched or tobogganed on the ice.
Shanties selling liquor, photographs and curiosities abounded. On February
4th 1912 the ice bridge broke up and three tourists lives were lost.
There can also be a great deal of "mini-icebergs" which flow down the
Niagara River from frozen Lake Erie. The flow of ice has been reduced
considerably by the yearly installation of the "ice-boom" on Lake Erie. The
ice-boom is a long floating chain (2miles- 3.2 KM) of steel floats strung across
the Niagara River from Buffalo New York to Fort Erie Ontario.
It is set in place during the month of December and removed during the
month of March or April. It is maintained by the New York State Power
Authority. The ice boom helps prevent the ice from clogging the river and most
importantly the hydroelectric companies water intakes.
Here it says in 1848 ???
HOWEVER.... The flow of water was stopped completely over both falls
on March 29th 1848 due to an ice jam in the upper river for several hours. This
is the only known time to have occurred. The Falls did not actually freeze
over, but the flow was stopped to the point where people actually walked out
and recovered artifacts from the riverbed!
Scroll down a ways to get to pic and info;
http://www.niagarafallslive.com/Fact...gara_Falls.htm