Zebra mussels (Dreissena polymorpha) have caused significant ecosystem changes across North America since their introduction, yet their effects on fish populations remain poorly understood, particularly in Great Plains reservoirs. We quantified effects of zebra mussel invasions on water quality and fish assemblages across 25 reservoirs >5 km2 in Kansas, U.S., where invasions have occurred over the past 2 decades. Using data from invaded reservoirs before and after they were invaded, and data fro