iOS - PocketEarth.
About 8-10$, IIRC. It uses OpenStreetMap, and downloads, no charge.
Relevant to your question is that you can pay another 8-10$ and unlock the download topo maps for areas that have them. More exactly, I think it downloads contours, and some things, like say trails, might still be coming from OpenStreetMap, rather than a full-on hiking-type, high-detail, topo map. It's vector based, so it zooms in and out very well.
Used on an iPad, it's quite good. Even a small phone is quite acceptable (I have an SE). Note that iPads come in wifi-only and cellular flavors. Only the cellular (about $150 more) has on-board GPS, which works even if you don't put in a SIM for it.
It also downloads landmark descriptions off Wikipedia and you can put annotated markers on the maps. One drawback is its zoom in/out hiding of features - if you're talking about a really small trail or road, Pocket will hide it until you zoom in enough, even if the general area is featureless and has no other roads. That does make it hard to plan a big picture trip (you can add your own markers to let you where to zoom, but...).
and a zoom on the lake in the lower left
I have no affiliation with them, but I love this app, for camping and for traveling as well.
Edit: for some reason, their contours only download for the lower half of SK, your lake is in the twilight zone, apparently. This is odd, I have seen contour data for everywhere else, including in Peru.
Here's a point about 300km due south of your lake, which is in the topo coverage area.
iOS - "Topo" app
Topo, free IIRC, is in many ways much more rudimentary than PocketEarth, but it does acquire general topo maps for Canada (3 different types). It does not show grid lines, and worse, does not display your GPS location, but it does stitch topo tiles (of the same type) together.
Here's a location near your lake, with 2-3 tiles stitched together. I've added the lines and flag, which provide very basic annotation capability. You can apparently also add GPX maps. It has gotten better since I first used it, and stopped doing so, now it looks more optimized in terms of zoom and lag time.
note: zooming in does not show all that much more (this is a raster, not vector, map), except that labels for place names, like the Brustadt river here, become apparent.
Also, Government Canada provides freely downloadable topo maps (not always recent), once you figure out their very confusing website. I've done it before, and gotten my maps, but it's painful. Here's an entry point for it.