Hydrogeology of the Rocky Mountain House area, Alberta

The Plains portion of the Rocky Mountain House map-area and part of the Foothills, totalling about 90 percent of the area, are underlain by the Paskapoo Formation of Late Cretaceous-Tertiary age down to and below the limiting depth of investigation, 1000 feet below ground level. Evaluation of pump and bail tests and interpretation of spring flow rates and other field phenomena indicate that the approximate average 20-year safe yield of wells completed in this formation is 25 to 100 igpm (approx. 100 to 500 l/min). Lower yields, of 5 to 25 igpm (approx. 25 to 100l/min.) and in places of 1 to 5 igpm (approx 5 to 25 l/min.), are predicted for smaller areas within this formation. These lower yields are due to: lack of clean, permeable, extensive sandstone beds; low available drawdown in recharge areas; and, in the Foothills, to probable destruction of primary porosity by cementation and by low temperature metamorphic effects due to diastrophism. Yields of 100 to 500 igpm (approx. 500 to 2500 l/min.) and locally over 500 igpm are predicted for local, generally low-lying areas where the combination of extensive high permeability zones and high available drawdown exists. Occasionally, induced infiltration from lakes or streams may be effective.