Open File Report 2019-08

Open File Report 2019-08

OFR 2019-08

Environmental Isotope Sampling of the Saddle River and the Groundwater Observation Well Network in the Upper Peace Region, Northwestern Alberta

Author(s) Smerdon, B.D. Date 2019-09-11

Waters samples were collected for isotopic (stable isotopes of water [δ^2H, δ^18O], tritium [^3H], radiocarbon [^14C]) and geochemical analysis from five locations on the Saddle River during low flow conditions in 2017 and four Groundwater Observation Well Network (GOWN) wells in the Upper Peace Region in 2018. The Saddle River is composed of relatively young water with a total dissolved solids (TDS) concentration that varied from 731 to 902 mg/L and a mixture of young (^3H) and old (^14C) naturally-occurring tracers. The downstream trend of increasing TDS and decreasing ^14C indicates that the Saddle River receives baseflow from progressively older water sources in the downstream direction, suggesting that groundwater from the underlying bedrock formations has varying residence times. Groundwater from an observation well completed in surficial sediments (sand) also indicates relatively young water most likely recharged from snowmelt in the region. Groundwater from observation wells completed in the Wapiti Formation did not detect any ^3H, had lower^14C values, and moderate TDS values (910 to 2600 mg/L). These findings indicate the presence of older groundwater in the Wapiti Formation at these locations, potentially in the order of 15 000 to 25 000 years before present. This water sampling in the Upper Peace Region provides a “snapshot” of conditions for the 2017/2018 period.

Smerdon, B.D. (2019): Environmental isotope sampling of the Saddle River and the Groundwater Observation Well Network in the Upper Peace Region, northwestern Alberta; Alberta Energy Regulator / Alberta Geological Survey, AER/AGS Open File Report 2019-08, 6 p.