Flap gates and stop logs are water-level control or flood retardation structures susceptible to zebra mussel macrofouling. These infestations could lead to improper sealing of a flap gate or stop logs resulting inoperable reservoir or drainage control. Control strategies relating to reservoir level control structures include mechanical cleaning, leaving one stop log in place permanently on the bottom (so grooves would not be fouled), and the use of antifouling coatings.