Demonstration of a methodology for setting ecological flow and water level targets

Abstract

This paper demonstrates a methodology developed through applying and refining Lake Simcoe Region Conservation Authority (LSRCA) and Bradford’s (2011) framework for setting ecological flow and water level targets. Each step of the methodology is described along with an example application within Lovers Creek subwatershed. The methodology requires subwatershed objectives and habitat specialists to be defined. Study nodes are selected and the reference streamflow regime is characterized along with the hydrological alteration that has occurred, or is expected to occur under a given scenario. Potential ecological responses to the various hydrologic alterations are then identified. Methods for setting overall ecosystem health and specific ecological objective flow targets are discussed and demonstrated. The targets are then integrated into a flow regime for each study node and a process for using this information for decision-making is suggested. The targets developed using the methodology presented in this paper are mainly limited by the accuracy of the hydrologic model and the quantified flow magnitudes. Recommendations for improving these components of the assessment are made. The unique approach presented in this paper provides explicit steps for developing flow targets for subwatersheds within Southern Ontario and beyond. This research contributes toward the advancement of ecological flow assessment within Southern Ontario, which provides opportunities for enhanced protection and restoration of ecosystem health across the Province.