Control of Algae at Appleton, Wisconsin

year 1939 will be remembered among water works men in the Middle West either as a year with extraordinary algae troubles, or as the beginning of what may prove to be a perennial siege of extremely abundant algae growths. It is hoped that it was merely an unusual year. Difficulties experienced with algae at Appleton, Wisconsin, in 1939 were not greatly different in character from those encountered with microscopic organisms in other places and at other times. Discussion of them is warranted only because they were unusually severe. This does not purport to be a profound research paper on algae troubles and their cures. In times of great stress one cannot take the time to lay out and follow through accurate and complex investigations and experiments; routine must be increased to take care of critical conditions and there is little time for anything but the things requiring immediate attention. The source of the Appleton water supply is the Lower Fox River that carries the overflow from Lake Winnebago to Green Bay. The river water at Appleton, six miles down the river from Lake Winnebago, is practically the same as the water in the lake except that domestic sewage and trade wastes, from a population of about 242,000, are contributed to the river at Neenah and Menasha after primary treatment. The cities of Oshkosh, Neenah, and Menasha and numerous paper mills also use Lake Winnebago as their source of supply (see Fig. 1). Lake Winnebago is oval-shaped in outline with a maximum length of 30 mi. and a maximum width of about 10 mi. Its average depth is 15.5 ft. with a maximum depth of 21 ft. The capacity of the lake