Myths of abundant and stationary water resources have infl uenced water policy and
management in western Canada. Data presented in this chapter demonstrate that
water use, policy and management were established during a period of fairly stable
and reliable water supplies as compared to preceding and projected hydrological
regimes. These data include tree-ring and historical evidence of prolonged drought,
recent trends (glacier wastage, declining snowmelt runoff and summer fl ows), and
global circulation models (GCM)-based scenarios of precipitation and runoff. We
consider how water policy and management might be adjusted to compensate for a
long-term view of the surface hydrology that includes more prolonged drought and
lower average flows than observed and experienced in the twentieth century.
