Observation well WSA Tessier was constructed in 1967 to a depth of 26.05 metres to observe natural groundwater level fluctuations in an intertill aquifer. The aquifer is underlain by Sutherland Group tills and overlain by Saskatoon Group tills. A portion of the water infltrating the aquifer moves laterally towards Eagle Creek where it discharges, while a portion moves down into the Judith River Formation and then laterally to the east into the Tyner Valley aquifer.
The WSA Tessier hydrograph shows that seasonal minimums typically occur in March-April while maximums occur in July-August. The well experiences significant annual fluctuations which vary from around 0.10 to 1.5 metres. The record low water level of about 544.1 metres for WSA Tessier occurred in 1991 following five years of little or no recharge. Several years of strong recharge led to a record high peak of about 548.1 metres in 2012. Water levels remained high in 2013.
WSA Tessier yields water of the calcium/magnesium-sulphate/bicarbonate type with a sum of ions concentration of approximately 1370 mg/L.