AN INITIAL EVALUATION OF HABITAT ENHANCEMENT STRUCTURES IN BYERSVILLE CREEK, PETERBOUROUGH, ONTARIO

As part of mitigation for a commercial development adjacent to Byersville Creek in Peterbourough, Ontario, a series of instream structures were installed along 250 m of channel to improve channel form and function, and concurrently enhance aquatic habitat. Byersville Creek is a cold water stream that was previously realigned as a straight channel. No apparent effort was made to provide morphological variability. Upstream urbanization has impacted the stream by providing a continuous supply of sand, which further degraded the system by reducing complexity. Immediately downstream of this site, spawning brook trout have been observed recently, and therefore it is likely that the study reach was also utilized as a spawning ground prior to straightening and other urban impacts. In support of the channel and aquatic habitat rehabilitation, a detailed geomorphic assessment was completed. This assessment included characterizations of channel morphology, substrate and other relevant geomorphic characteristics. The assessment indicated that the primary limiting factors with regard to aquatic habitat were the lack of pools, the limited instream refugia, and the homogeneous composition of bed materials which was typically 0.2 to 0.3 m deep. To aid in alleviating these deficiencies, a series of rock vortex weirs and paired log flow deflectors were installed to promote bed scour and bed material variability. Following installation, a monitoring program was initiated to assess the success of the instream structures. The monitoring includes periodic measurements of channel geometry at the structures, characterization of bed materials, point velocity measurements around the habitat structures, and fish and benthic surveys. The initial post-construction monitoring results and evaluation of the success of the structures are presented.