Reconstructions of past climate, and climate model projections,
both undermine the validity of the assumption of stationarity – a
foundational concept in water resource engineering (Milly et al.,
2008). The tree-ring study commissioned by EPCOR had provided
further evidence of non-stationarity of the hydrologic regime. In
2012, EPCOR released ‘‘Source Water Protection Plans – Edmonton’s
Drinking Water System’’ for wide distribution. This document
included our tree-ring reconstruction of annual river flow and made
reference to ‘‘an innovative method of tree ring growth correlated
with the precipitation record to extend the gauge record for the
NSR.’’ The substantive report concluded ‘‘Understanding that water
resources are not stationary, water management must be adjusted
to a hydrological cycle which is increasingly sensitive to the timing
and frequency of rainfall events, and has less of a buffer from glacier
ice and late snowmelt.’’