Biscayne National Park (Florida, USA) is to establish a "soundscape preservation plan," the first of its kind. So far it appears to be a study of the non-natural environmental sounds, rather than any restrictions, so it's not yet up to the levels wanted by Gordon Hempton's "One Square Inch of Silence" campaign. As human-made environmental noises become increasingly unavoidable maybe there will be a higher demand for true silence.