That is a good question. Everything leaks, of course. The tailings ponds that you're speaking of, with the capture wells as well as the perimeter ditches, are specifically designed to return that leakage back into the process-affected recycle stream.
There is one discontinued tailings pond in the process of being reclaimed right now that I'm aware of. That's pond 1 at Suncor. There has historically been estimated to be very small leakage directly into the Athabasca River from that, and I believe there's been about two decades' worth of studies, required by Alberta Environment and carried out by various researchers, as well as by Suncor, showing that there's absolutely no effect from that legacy pond.
I'm not aware of any other leakages from other ponds. In our environmental impact assessments--of course, sometimes we get criticized for being so conservative--we do show that very minute amounts of seepage can potentially reach receiving streams, but as Alberta Environment has very clearly said in recent publications, they are not allowing any seepage to occur, and the capture of all seepage is expected. Monitoring wells that are in place and will be required by Alberta Environment will ensure that if there is seepage detected, that seepage will have to be returned to the tailings pond.