BoatUS also has a children's PFD loaner program.
SD's right. From BoatUS's website:
How the Program Works:
BoatUS Foundation accepts about 40 new sites into the Life Jacket Loaner Program during each application cycle. The group or waterfront location accepted into the program will receive 12 child-sized life jackets, as well as signs, brochures and a sign-out binder. The life jackets should be displayed in prominent locationólike near a boating ramp, in a marina office, or near a fuel dock. A boating family can then check out the life jacket for a day, free of charge. At the end of the boating trip, they can return it to the same location.
If you are interested in being a life jacket loaner site or would like additional information on the program please contact the program administrator at firstname.lastname@example.org.