Every year, between Christmas and New Years, it is completely drained by opening a huge gate near Nueva St. and only a trickle of water is left. Then they walk over the bottom and pick up tables, chairs, cell phones, purses, wallets, salt and pepper shakers, bottlles, cans, baby buggies (no babies), strollers, hub caps, platters, ash trays, money, credit cards, sun glasses,.....well, a whole array of items dropping in by some of the 6 million visitors every year. One year they even found a car engine! It very interesting to watch. They do not dig or pick up any Alamo or historical relics....even though a cannon has been spotted ....that can only be done wih a permit from the state and they don t go to the trouble.
During the Mud Festival in January after the holidays. It would make no sense to drain it during the most active tourist time of the entire year which is the Christmas season with all of our beautiful Christmas lights. We even choose a mud King and Queen. It takes a week to clean. This year, as we have added to the Riverwalk both buildings and sculptures, we will probably find new things when it is drained.
i believe its once a year