What I would do and i'll preface this by it may be beyond repair.
On the bottom dril 1/2 holes and add dowels like you did on the side. that will help reinforce that split.
Then to try and save it get a 1/8 " metal or aluminum strip and drill holes in it for screws. 4-6 even spaced. then get screws that go about halfway into the leg from the bottom. screw that metal piece on it (bottom of leg). make sure its as long as like 3/4 of that leg and just a hair less wide. that should add some structural strength.
again it may be too weakened but why not try...
Informative. I have a catchment system and a solar pump to driplines as i have no water at garden. Works well