These have been created to provide water for our towns and cities, and are formed by building a massive clam across a steep sided valley so that the land behind the dam is flooded. Because the water is used for supplying domestic needs most water authorities restrict fishing to the use of artificial lures. This means that most reservoirs are run as trout fisheries where the rule is fly-fishing only. They are all artificially stocked with hatchery-reared brown and rainbow trout. The quality of the fishing depends on the management stocking policy, but most provide good trout fishing at a reasonable price. On some reservoirs the stocking takes place on one occasion before the season opens so that the first few weeks of the season produce lots of trout. As the trout are caught. The fishing becomes more difficult towards the end of the season. On other reservoirs the management release trout in batches throughout the season so that the level of sport remains constant. This is often re-ferred to as ‘put and take fishing. Reservoir trout fishing has enabled many more anglers to participate in fly-fishing than would otherwise be possible.