Management and Restoration Lessons from a Habitat Manipulation Study in a Recovering Urban Lake

Onondaga Lake (NY) was once considered the most polluted lake in the U.S.  Despite improvements in water quality beginning in the 1970’s, macrophyte coverage in the 1990’s was markedly low and juvenile fish production was limited.  The addition of a set of temporary wave breaks and macrophyte plantings in the 1990’s demonstrated that structure protected from wave action helped stabilize substrate, promote macrophyte growth, and increase fish spawning and nursery habitat.  Although four sites were originally proposed, a permanent wave break approximately 100 m in length was installed at a single site in 2001. Monitoring before and after installation (2000-2012) found conditions inside and adjacent to the wave break impaired as a result of the design and placement of the structure.  The accumulation of fine sediment behind the wave break reduced water quality, promoted algal growth, and prevented macrophyte establishment.  To date, fish nesting inside the wave break has been absent.  Although the lake continues to improve due to on-going restoration efforts and natural recovery, conditions inside the wave break remain relatively unchanged after more than a decade.  Though the wave break was unsuccessful, the habitat manipulation study provided valuable information that contributed to the Onondaga Lake Habitat Restoration Plan.