Observation well WSA Lilac was constructed in 1965 to observe natural groundwater level fluctuations in the Battleford Valley Aquifer System in west-central Saskatchewan. The well was completed to a depth of 122.5 metres in a sand and gravel deposit of the Empress Group in the buried valley aquifer. The aquifer is overlain by drift, consisting mainly of till and receives recharge through vertical flow and possibly by lateral inflow from adjacent aquifers. The direction of the groundwater flow in the aquifer is southeast toward its discharge area in the North Saskatchewan River valley north of Langham.
The record low water level on the hydrograph of about 537.9 metres occurred in 1968. Since that time, with the exception of a decline from 2000 to 2003, the aquifer has shown an increasing water level trend. In 2013, water levels peaked at a record high of around 538.75 metres. Annual fluctuations are typically less than 0.2 metres with water levels peaking in spring followed by lows in late winter. These seasonal fluctuations have been attributed to near surface seasonal loading.
The water is of the calcium/sodium-bicarbonate/sulphate type and has a sum of ions concentration of approximately 1150 mg/L.