Police say they found the shooting victim in the Murrumbidgee River a short distance from the park, but after refusing to exit the river, he swam to an island and climbed a tree.
That kicked off a 12-hour police operation to get him down, eventually ending about 2am on Friday with his arrest.
He was treated in hospital, where he also faced a bedside court hearing on a charge of wounding with intent to cause grievous bodily harm.