On October 31, 2013 Onion Creek experienced historic levels of flooding, cresting at 40.15 ft, a level not seen since 1921.[3][4] Over the course of 4h 9-10in of rain fell in the Onion Creek watershed.[5][6][7] The flood had a flow rate of over 120,000 cubic feet per second, more than twice that of Niagara Falls. In the end, five people died and more than 500 homes were damaged by flood waters.[8]
As a result of the flood the City of Austin purchased hundreds of homes in the floodplain in 2015.[8][9] These properties have formed the northern section of the Onion Creek Metropolitan Park since 2019.[10]