Abstract: The present invention provides apparatus and method for increasing the wastewater treatment capacity of an existing pond treatment facility wherein the facility includes at least one treatment pond and means for bringing influent wastewater to the pond. Apparatus according to the present invention includes a porous baffle placed into the pond so as to separate the pond into two separate and distinct, but fluidly connected portions. The baffle thus divides the pond into a first portion for treatment of biological solids in the wastewater with the use of concentrated bacteriological growth and a second portion which provides a reservoir to accommodate high rates of wastewater flows and organic loads such as will occur with storm water flow.