The New York Canal is already about half full but by the end of the week there will be a lot more water in it.
Both irrigation districts and firefighters want to remind everyone about the dangers now.
"Our water rescue team on the Boise Fire Department gets multiple calls every summer for people that have either fallen into the canals or purposely get in the canals to swim and they find that the water very cold and very swift and they cant get themselves out," said Battalion Chief David Cooper
The canals are designed to move a lot of water fast. The temptation for a quick dip all too often turns deadly. Last summer, two men drowned in canals in the Treasure Valley.
"The New York Canal here in particular has got concrete lining on each side. It runs fast enough and the sides are slick enough that once you get in it, it's very difficult to get out," said Cooper.
Cooper says now is the time to remind your children not to play near or in the canals.