Imbalances in the kinds of recreation available in various parts of the Basin are another problem, sometimes rooted in the nature of things, sometimes remediable. The outstanding one is the shortage in the upper Basin of what is called "flat water"--lakes and reservoirs suited for mass recreation of kinds for which a really major demand exists and is growing: swimming and motorboating and water-skiing, besides fishing of the type possible only in such water. It has been said that recreation is potentially Appalachia's most profitable industry. If so, Potomac Appalachia badly needs more such water to fill out the resource and to attract the many people who are interested mainly in flat-water activities. Middle sections of the Basin want and can use it as well. A clear indication of the demand, as well as an additional good reason for trying to meet it, is seen on weekends along the occasional narrow stretches of slack water found in the Potomac and the Shenandoah and even the slim South Branch, where ski boats roar up and down among apprehensive swimmers and unhappy anglers, a classic instance of the kind of destruction of pleasure that occurs when incompatible recreational pursuits are forced together by a want of room for both. The obvious answer is to locate and design the reservoirs needed to meet Basin water demands in such a way that they can not only fulfill that purpose but can provide needed recreation too. The major reservoirs called for to achieve near-future supply purposes are few, but they can be planned in places where they will get a maximum of these types of use and where drawdown and other unesthetic effects will be minimal. And the smaller headwater structures needed for water supply, flood control, and other purposes throughout the Basin can quite often be designed to function as first-rate recreational attractions too. [Illustration] Anglers vary widely in their tastes. Some like the pursuit of bass and sunfish in reservoirs, and for them the upper estuary as well will be a good place to go when it is suitably cleaned up. Some want wide salt water and the lonely cry of gulls, and these the Basin can provide also. Others prefer trout in highland streams, or smallmouth and catfish in the big flowing rivers, and as the state of the waters grows better, so too will all these kinds of fishing. On certain rivers and streams particularly, the assured flow that is going to be needed to cope with diffuse pollution will have a strong good effect on aquatic life and sport fishing. The Monocacy and the South Fork of the Shenandoah are examples. And in the Potomac falls and gorge below the metropolitan water intakes, as was noted in Chapter III, assurance of a certain minimum flow would be justifiable on esthetic and recreational grounds alone, even aside from the need for it below in terms of water quality.