The continued effort to improve water quality and reduce nonpoint source pollution will hinge largely on a little-known pollution control strategy known as total maximum daily loads (TMDLs), which describe the amount of a particular pollutant that a water body can absorb on a daily basis while remaining safe for wildlife and people. While by no means a comprehensive explanation of all the factors surrounding this complex subject, this issue of Western Water provides a snapshot of TMDLs and what they mean for water quality, supply and reliability.