Update: planted the trees very close to the water, dumping a bunch of plant food in the hole prior to planting. They already seem to be doing very well and I might only have lost one due to some animal digging at the roots. Possibly a raccoon, judging from tracks. In the future (and a note to anyone else) I will buy a plastic circular mat to place around the base of the tree right off the bat. The mats seem to have kept digging animals at bay, but might have been too late for one tree. Will update again next year when things get green again.