Figure 1 - Alum-dosing in Lake Rotorua

Treating Lake Rotorua's incoming streams with low levels of aluminium sulphate has effectively reduced the amount of phosphorus entering the lake and reduced algal blooms. One of the people we interviewed told us: "[Before the dosing] I didn't take my kids out to the lake, but now I do. When I was a child, we would swim in Lake Rotorua, but we started to notice the smell that the water would leave on us and we stopped. In some of the lakes, you would notice the weed and the gross feeling – but now that has changed." Photo of Lake Rotorua courtesy of Bay of Plenty Regional Council.