Free water is worth the effort to get, but you won't be pumping clean water, and it won't be at pressures high enough for some sprinkler heads. How large an area do you want to cover?
By the way, even without the 75 foot distance between pump and water, you couldn't use a one inch suction pipe. Figure two inch pipe. What elevation difference between pump and canal level? (this figures into the suction lift, which should be kept to a minimum)