Water Quality and Sediment Behaviour of the Future: Predictions for the
21st Century (Proceedings of Symposium HS2005 at IUGG2007, Perugia, July
2007). IAHS Publ. 314, 2007, 137-144
Long-term
trend of uranium concentrations in Beaverlodge Lake, Saskatchewan, Canada,
under mine decommissioning
HUAXIA YAO1, ROBERT KIDD1 & MICHIO HASHINO2
1 Environmental Protection Branch, Department of
Environment, Box 3003, 800 Central Ave, Prince Albert, Saskatchewan S6V 6G1,
Canada
huaxia.yao@gov.sk.ca
2 Department of Civil Engineering, The University
of Tokushima, 2-1 Minami-josanjima, Tokushima 770-8506, Japan
Abstract The
annual mass balance of uranium for Beaverlodge Lake (which is impacted
by uranium mining) was analysed using limited observation data. Annual
water discharges of the basin, or discharges at the lake outlet are estimated
using the discharge ratios of a sub-basin from 1985 to 2006. Uranium loadings are determined using observed concentrations and
discharges from two
creeks flowing into Beaverlodge Lake. The relationships between inflow
loadings, outflow volumes and lake concentration changes are established.
Then, given the trends of loading, the long-term trends of outflows from the
lake and concentrations in the lake are predicted. Along with a continuous
reduction in loadings from 3473 kg/year in 1985 to 0 kg/year in 2092, uranium
concentration of the lake decreases from 125 mg/L in 1985 to 10 mg/L in 2118. The natural restoration of the
lake water would need 112 years to reach the 10 mg/L Canadian drinking water
standard.
Key words trend; uranium; lake; mine decommissioning; Saskatchewan; mass balance;
loading; discharge