After partial completion of the Lakewood Filtration Plant at Duluth, studies were begun with funding provided by the demonstration grant. Research covered a variety of topics and was done with a 10 gpm pilot plant located at the filtration plant, with the full scale plant operating at 20 MGD and 30 MGD, and in portions of the water distribution system. Water treatment plant sludge disposal also was studied. An extensive program of raw and filtered water quality monitoring was conducted. Monitoring techniques evaluated at Duluth included the transmission electron microscope for fiber counting, x-ray diffraction for amphibole mass, two types of particle counters, and two turbidimeters. Chemical treatment aspects studied included the effect of point of fluoride addition on alum coagulation and the use of inhibitors to control corrosion that occurred after alum coagulation was undertaken. Natural freezing was found to be a very effective means of dewatering alum sludge.