Howe Lake (formerly called "Goudie Lake") is an unusual feature of southeast Saskatchewan. Almost perfectly circular (diameter 295 n~) , it is much deeper (26 m) than almost any other prairie lake. Initially noted in 1952, numerous investigations culminated in deep drilling and geophysical programs in the 1969-1976 period. The lake is the surface expression of a deep, funnel-shaped depression filled with coarse colluvium at the bottom and finer material near the top. A central pipe extends to a depth of at least 138 m. Radiocarbon dates and the history of deglaciation give evidence that the structure was formed between 12 000 and 12 500 years BP, shortly after the last ice sheet melted in the area. The structure was probably formed by a hydrodynamic blowout of water from the Mannville Group 400 m below surface. Extreme overpressure of water in the Mannville Group was probably induced by recharge from meltwater of the continental glacier then standing a few kilometres to the north of Howe Lake. The blowout was initiated at Howe Lake by fractures in the subsurface, related to a salt solution-collapse structure. Howe Lake probably served as a valve controlling the artesian pressure in the Mannville Group over a large area, until the active ice margin had retreated northeastward exposing lower elevation discharge areas. Hydrodynamic blowouts provide another .process for the origin of breccia-filled pipes.Le lac Howe (appelk autrefois "lac Goudie") prksente une forme inhabituelle pour le sud-est de la Saskatchewan. Etant presque parfaitement circulaire (diamktre 295 m), il est beaucoup plus profond (26 m) que la grande majoritk des lacs des prairies. C'est en 1952 qu'il fut remarqut et depuis de nombreuses Ctudes se sont accumulkes suite aux programmes de forages profonds et de gkphysique qui furent rCalisCs entre 1969 et 1976. Le lac traduit en surface une dkpression profonde en forme d'entonnoir remplie de dCp8ts colluviaux a grain grossier au fond et de matkriaux plus fins prks de la surface. Une pipe centrale plonge jusqu'a une profondeur d'au moins 138 m. Des datations au radiocarbone et l'histoire de la dkglaciation indiquent que la structure s'est formke entre 12 000 et 12 500 annkes avant le prksent, peu de temps aprks la fonte de la calotte glaciaire. La structure rtsulte probablement d'un claquage hydraulique dB ?I jaillissemeit violent ei soudain de l'eau du groupe ~a n n v i l l e gisant h 400 m sous la surface. Une surcharge excessive de la ~ression de l'eau du erouve Mannville fut induite probablement par une recharge h meme les eaux de fonte du ilacier continentaiqui stagnait 5 quelGes cilomktres au nord du lac Howe. Le claquage fut amorck au lac Howe par les fractures h la subsurface relites ?I une structure d'effondrement provoqute par la dissolution d'une assise de sel. Le lac Howe a probablement servi de soupape contrdlant la pression artksienne dans le groupe Mannville sur une grande surface de la rkaion, ius~u'au temps de recul du front actif du glacier vers le nord-est mettant hjour les zones de ...

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During the Canada Winter Games (1971) more than 4000 cars were parked on the ice cover of Blackstrap Lake during the skiing events on Mount Blackstrap. The rapid increase in winter recreation activities will result in increased use of ice covers for sporting events and parking. Ice thickness and buoyancy measurements were made at regular intervals over the lot during the 3 weeks immediately prior to the Winter Games. Continuous recordings of the ice surface deflection were obtained in the critical loading area. Systematic loading trials of increased magnitude were carried out to measure the static and dynamic performance of the ice cover. During the Winter Games the design load distribution was adjusted daily so that it was equal of less than the observed buoyancy of the ice cover in the parking area. This load distribution was achieved by controlling the parking density. This criterion provides a conservative estimate of the allowable distributed load for loading periods of several hours duration.The procedures developed provide a reasonable guideline for the safe use of freshwater covers for similar events.

Single-point resistance and spontaneous potential logs in fresh-water filled rotary-drilled test-holes provide data useful in geohydrologic studies in Saskatchewan. These geophysical logs are made by many of the water well drilling contractors in Saskatchewan on a routine basis. The logs provide good resolution of various lithologic units and provide data required to estimate the salinity of water in sand beds prior to constructing a well.Caliper logging offers a potentially useful method for evaluating hole conditions and the effect of drilling techniques on the formation in completion zones. The casing collar locator log run in a previously constructed well near Estevan demonstrates that this device can provide an accurate and objective measurement of the position and length of each joint of casing, the position of the screen assembly, and the location of screened and blanked intervals within the screen assembly. This tool should find general application in water well construction and maintenance practice.The neutron-epithermal neutron log provides a method of measuring the porosity of sand and gravel beds. The response of the gamma log is similar to that of the spontaneous potential log and the neutron-epithermal neutron log deflects in a fashion similar to the resistance and resistivity logs. Nuclear logs offer the advantage that they can be run in cased or uncased boreholes which may be filled with any type of fluid. They require more complicated and expensive instrumentation and slow-speed logging to obtain the required resolution. The normal resistivity logs offer the possibility of determining the concentration of dissolved solids in the formation water. The gamma-gamma log is a poor alternative to the natural gamma and neutron log for stratigraphic correlations.