The estuary's 200,000 acres of superb recreational potential are a case in point. It has a few drawbacks that can and ought to be dealt with, like the thousands of old sunken pilings and stakes that make boating dangerous in many places, and some others that may be tougher to eliminate, like the great annual summertime incursions of stinging jellyfish in its lowest reaches, the milfoil weed that sometimes clogs its tributaries, and the erosion of its shores by winter storms. But even as it stands, it offers fishing and boating and hunting of the finest sort in its lower part, with excellent swimming higher up where salinity drops and the jellyfish cannot come--a zone whose useful length will increase upstream as metropolitan pollution diminishes. Yet along the estuary's shores, except at certain historic sites like Wakefield where types of use have to be limited, there are only two major public parks at present and very few other public areas of any size where people can launch boats, fish, camp, or merely get at the open water. Some of the great military bases there are closed to the public, while others permit limited use. The main stem of the flowing Potomac is parallelled on the Maryland shore by the C. & O. Canal in Federal ownership, a unique resource. But the bulk of the land between the canal and the river--7200 acres out of 10,000--is privately owned. Along most of the 120 miles where the canal property touches the Potomac it is much too narrow to permit heavy use, so that public enjoyment of the river except at occasional spots is limited to hikers, cyclists, and boatmen. Maryland's Fort Frederick State Park, which joins the canal property and forms a much-frequented node of public use, is the only such park on any of the main rivers of the upper Basin. Federal and state forests, extensive though they are, are mainly confined to the ridges, as is the Shenandoah National Park. On the two forks of the Shenandoah and its main stem below their junction, very little public land exists despite the big segment of National Forest in the Massanutten range between the forks, and on the Cacapon there is hardly any. Authorized additions to the Spruce Knob-Seneca Rocks National Recreation Area will bring parts of the fine, clean mountain forks of the South Branch into public ownership and use, but the main stem of that river farther down is shut off. Fee-entrance places and State or local fishing access points are sparse, so that for the most part the Basin's main flowing streams remain a closed book for people who lack the time, youth, equipment, or inclination to come at them by canoeing or some other more or less arduous means. And, as was noted earlier, the shores of most of them urgently need some sort of reasonable protection against vacation clutter, so that a certain amount of public ownership or control would help save the rivers as well as provide recreation.