Pat - it's probably "effluent water", which is treated sewage that has been prepped for discharge back into "nature". Many golf courses are converting to effluent water since it doesn't count against their groundwater permit$, but with the effluent comes plenty of nutrients - and algae, unless the water has a adequate bloom that limits sunlight penetration.
During the midst of the 2013 drought, the city of Wichita Falls (TX) was preparing to switch their potable water supply to effluent-sources since the City's water-supply reservoir had dwindled to 15% of normal pool. You know it's bad with you're faced with that option. Fortunately, they finally received a week of rain that completely filled the reservoir.
