Both federal and state water pollution control statutes require dramatic reductions in waste discharges, but not their total elimination. Those statutes require establishing water quality standards for receiving waters and presume that they will be adequate to assimilate the residual post treatment wastes. But nothing is those statutes assures that minimum flows for waste assimilation in fact will remain in existence. Neither the common law nor eastern and western diversion permit statutes expressly provide direct means for establishing such minimum protected flows for residual waste assimilation. Those means include establishing minimum flows for fish and wildlife habitat and recreation purposes in some eastern diversion permit states, authorizing appropriations for some purposes in some western states, and requiring protection of environmental values in those states that recognize public trust or have enacted environmental protection statutes. Because of the haphazard and inadequate characteristics of those indirect means, states should establish direct regulatory authority for establishing minimum protected streamflows for waste assimilation.
Peter N. Davis, Protecting Waste Assimilation Streamflows by the Law of Water Allocation, Nuisance, and Public Trust, and by Environmental Statutes, 28 Nat. Resources L. J. 357 (1988)