A GENERAL PROTOCOL FOR RESTORATION OF REGULATED RIVERS

Large catchment basins may be viewed as ecosystems in which natural an d cultural attributes interact, Contemporary river ecology emphasizes the four-dimensional nature of the river continuum and the propensity for riverine biodiversity and bioproduction to be largely controlled b y habitat maintenance processes, such as cut and fill alluviation medi ated by catchment water yield. Stream regulation reduces annual flow a mplitude, increases baseflow variation and changes temperature, mass t ransport and other important biophysical patterns and attributes, As a result, ecological connectivity between upstream and downstream reach es and between channels, ground waters and floodplains may be severed, Native biodiversity and bioproduction usually are reduced or changed and non-native biota proliferate. Regulated rivers regain normative at tributes as distance from the dam increases and in relation to the mod e of dam operation. Therefore, dam operations can be used to restructu re altered temperature and flow regimes which, coupled with pollution abatement and management of non-native biota, enables natural processe s to restore damaged habitats along the river's course. The expectatio n is recovery of depressed populations of native species, The protocol requires: restoring peak flows needed to reconnect and periodically r econfigure channel and floodplain habitats; stabilizing base-flows to revitalize food-webs in shallow water habitats; reconstituting seasona l temperature patterns (e.g. by construction of depth selective withdr awal systems on storage dams); maximizing dam passage to allow recover y of fish metapopulation structure; instituting a management belief sy stem that relies upon natural habitat restoration and maintenance, as opposed to artificial propagation, installation of artificial instream structures (river engineering) and predator control; and, practising adaptive ecosystem management. Our restoration protocol should be view ed as an hypothesis derived from the principles of river ecology. Alth ough restoration to aboriginal state is not expected, nor necessarily desired, recovering some large portion of the lost capacity to sustain native biodiversity and bioproduction is possible by management for p rocesses that maintain normative habitat conditions. The cost may be l ess than expected because the river can do most of the work.