I’ve mentioned several times about the broken ledge that comprises some of the bed for my woeful Lake Marguerite. The photo above is an example of one bit of it. This is, by far, the worst-looking patch, at least in terms of solidity. I suppose much of this cracking and splintering is only surface deep, but it wouldn’t take too many breaks like these deeper within to drain a lake.
This ledge business is a fact of life at Roundrock. I’m either going to make the lakebed hold water or I’m not given the physical setting. This ledge, and a similar but more exposed one across the lake, make up the “sides” of the lakebed. The earthen dam interrupts the run of the ledge, but it reappears on the dry side of the dam. In the spring, after we’ve had some serious rains and the lake is briefly at full pool, these exposed ledges on the dry side of the dam do not have flows or trickles of water coming from them. I take that as a sign that I’m not getting leakage from the broken ledge that is temporarily underwater upstream.
Nonetheless, when we were last out there, we put some effort into covering this bit of ledge with Bentonite, as you can see in the photo below. (These two shots look at the same thing from opposite angles.)
It is possible that in a heavy rain, the Bentonite below will be washed into the lake rather than into the cracks where it is resting. While that wouldn’t be bad for sealing leaks farther below, it wouldn’t do anything for the leaks that may be in the ledge. However, these ledges are close to what would be the shoreline at full pool, so they would be within hand-casting distance if I choose to stumble along the shore with a bucket of Bentonite. That may be the best time to try to fix a crack leak since the water flowing into it would possibly pull the Bentonite along with it into the crack.