Stop Poisoning Florida Act This bill requires the U.S. Army Corps of Engineers (USACE) to prohibit certain discharges of water from Lake Okeechobee, which is Florida's largest freshwater lake. Specifically, the USACE must prohibit discharges of water from the lake through the Port Mayaca Lock and Dam or the St. Lucie Lock and Dam when the water exceeds the maximum concentration of microcystins (a toxin that is produced by blue-green algae) recommended for recreational waters by the Environmental Protection Agency.