Recent arguments that empirical evidence points to
hydrologic nonstationarity that is a consequence of
climate change cannot be dismissed. Yet the operational
assumption of hydrologic stationarity used extensively in
water management should not be discarded without
further study. It remains to be determined if assumed
forms of hydrologic nonstationarity would tax the ability
of water systems, through their robustness and resilience,
to absorb the additional stresses that would follow from
those assumptions. One approach to making the
determination is by way of an assessment of the expected
economic regret in water management resulting from the
use of the assumption of restrictive hydrologic stationarity
in the face of perceived hydrologic trends.