The Sweetwater Wetlands is closed to the public one day a year. In early March, Tucson Water and the Tucson Fire Department conduct a controlled burn to remove dead and thatched bulrush and cattail, which, if not removed, will eventually stifle new spring growth. (Images on this page are from the 2012 burn.)
The annual exercise also provides new Fire Department staff with valuable training and experience controlling fast-moving fires months before the normal wildfire season begins. The dead, thatched vegetation must also be removed to allow applications of granular mosquito larvicide to contact the water, which greatly improves the effectiveness of Tucson Water's Mosquito Abatement Program.
The roots of the bulrush and cattail remain viable during the burn and the vegetation quickly grows back within three to four months. No more than one-third of the Wetlands is burned in any one year to leave plenty of healthy habitat during the remaining winter migratory bird season. The burn is scheduled early enough as to avoid April black bird nesting. Typically on the day of a burn, migratory water fowl lift off at the first sense of fire and they return to the open ponds after the fires have burned out late in the afternoon. The Sweetwater Wetlands reopens to the public the next day.