Invasive species and disease are among the greatest contemporary threats to aquatic biodiversity and ecosystem functioning. The virile crayfish (Faxonius virilis) is an invasive ecosystem engineer that exhibits behaviors including burrowing and sediment transport and is experiencing outbreaks of crayfish plague. Diseased individuals can develop external lesions that may influence ecosystem engineering ability. We elucidated how crayfish engineering behaviors may impact stream biogeochemistry and bank stability using crayfish with or without visible injury. Male, virile crayfish were collected outside their native range in southwest Montana for use in a 24-hour study with mesocosms containing manually formed clay banks and stream water. We monitored burrow size, sediment movement distance, turbidity, and concentrations of stream nutrients including nitrate, nitrite, ammonium, and phosphate. We found that crayfish substantially disturbed the clay and reduced water clarity. All crayfish in this study exhibited burrowing behaviors and full bank collapses due to bioturbation occurred within 24 hours in over 90% of the crayfish trials. Crayfish with lesions burrowed as frequently and to a similar extent as crayfish without lesions. Instead, the magnitude of sediment changes was positively correlated to crayfish body size. The movement of stream bank sediment into main channels and weakening of bank structure has the potential to strongly influence concentrations of dissolved nutrients in streams experiencing high crayfish activity. As virile crayfish continue to invade new freshwater habitats and show novel patterns of disease expression, improved understanding of how engineering activities modulate abiotic stream conditions can improve predictions of the effects of future invasions on stream health, community structure, and ecosystem function.