Search

Many of the watersheds in southern Ontario have been highly modified to facilitate the removal of surface water from agricultural fields. These modified streams are often classed as municipal drains and are subject to periodic drain maintenance under the Drainage Act. Municipal (agricultural) drain maintenance involves removal of built-up sediment and associated aquatic vegetation, and may also include channelization of the stream and removal of riparian vegetation. Despite the periodic disturbance due to drain maintenance, agricultural drains are home to many fish species in southern Ontario, including species at risk. Beaver Creek, a tributary of the Niagara River in southwestern Ontario, is classed as a municipal drain and is home to a population of Grass Pickerel (Esox americanus vermiculatus), a species at risk in Canada. In the fall of 2011 a section of Beaver Creek was subjected to drain maintenance. In an effort to mitigate potential harmful effects of the drainage activities on the Grass Pickerel population, reconstruction incorporating natural stream channel design features was also implemented. The fish community of Beaver Creek was sampled in the impacted reach where maintenance occurred, an adjacent control reach that was not subject to maintenance, and a downstream reach where the two converged, from 2009-2013 and again in 2015. A series of before-after-control-impact (BACI) analyses were conducted to determine the effect of maintenance and reconstruction activities on the Grass Pickerel population and the physical and chemical habitat in Beaver Creek. BACI analyses were also conducted on three time scales to determine the most effective monitoring time frame for future drainage projects. Results of this study indicate that reconstruction incorporating natural stream channel design features had a positive impact on the Grass Pickerel catch per unit effort in the newly created pools and mitigated the effects of channelization on habitat characteristics such as stream velocity. The diversity of the stream fish community was not affected by the maintenance and reconstruction activities. Changing the amount of time that monitoring is conducted can influence the ability to detect effects of drainage activities. In this study, monitoring for at least three years prior to the drainage works, along with post-project monitoring of at least four years following was required to determine the effects of drainage activities. [ABSTRACT FROM AUTHOR]