ABSTRACT.Most water takings in Ontario in excess of 10,000 gallons per day for purposes other than domestic, farm, or fire fighting require authorization by permit by the Ontario Ministry of the Environment. The legislation imposes control beyond that under common law, but does not remove common‐law obligations. Permits may not be assigned without the Ministry's consent and do not create property rights in water. Permits to take ground‐water require permittees to ensure that sufficient water is made available for the needs of prior users who suffer serious water‐supply interference due to the taking, or to reduce the rate and amount of taking. Permits to take surface water require permittees to maintain sufficient downstream flow to protect downstream uses of water and natural functions of streams. Specific permit requirements for city wells in the rural Hunsburger Creek basin protect existing well supplies and require maintenance of streamflow for pond levels and fish. Tobacco irrigation in the Big Creek basin reduced streamflow significantly and requires development of more detailed water‐management plans for years of extreme demand. Ontario's permit program serves to resolve water‐use conflicts, furnishes information on use and provides one means for implementing managem