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 from uninvaded reservoirs, we evaluated changes in water quality parameters with random forest models, and we evaluated trends in long-term fish abundance data and creel data with generalized linear mixed models. Overall, we found minimal impacts of zebra mussel invasion on water quality, fish species abundance, or angler use. Random forest models estimated that zebra mussel invasions had little importance in predicting water quality, while reservoir identity was the strongest predictor. The 95% confidence intervals for abundance trends in invaded reservoirs included zero for all species except largemouth bass, which demonstrated a small, and likely not biologically meaningful, decrease following invasion. Furthermore, all fish species showed similar estimates for abundance trends in invaded and uninvaded reservoirs. Angler use also showed no response to zebra mussel presence. Although zebra mussel invasions might have other negative consequences (e.g., on water treatment facilities), our results suggest that invasions in Kansas reservoirs have not considerably affected water quality or fish populations in the past 2 decades.