Midwest Lake
Radon in surface water

• I made this map around 1980 and added the locations in blue in December 2021. The Midwest Lake orebody is indicated in black as "OREBODY", the Midwest A deposit by the blue letter A, the Roughrider deposit including the J-zone deposit by the blue letter R, and the Huskie zone by the blue letter H.
• Note that the official name of this lake is South McMahon lake. Geologists call it Midwest Lake after the name of the diamond drilling company that did the intial drilling.
• Note the high radon values near the Midwest orebody and low values elsewhere.
• The radon anomaly was confirmed in 3 different summers by 3 different operators, all before the orebody was discovered by drilling.
• First (1969), Bondar-Clegg carried out a water survey at a spacing of one sample per square mile. This survey included only one sample near the orebody and it ran 19 pCi/L in radon, which they identified as "probably anomalous". This sample was not anomalous in uranium.
• Later (1972), in a more detailed survey, I collected water samples by canoe from shallow water around the edge and analysed them for radon in a tent. My results are shown in the figure.
• Several years later the orebody was discovered by the drill (shown in solid black on the figure)
• All the lakes in the region should be sampled like this, and in favourable areas bottom samples should be tested as well.