Linking storm water management ponds & urban streams: function and ecological impacts

点击翻译按钮获取中文摘要

Storms can result in large amounts of water draining into urban streams and rivers, potentially resulting in flooding, erosion, and transfer of large amounts of sediments and nutrients from the land surface into rivers and lakes. To reduce flooding events and erosion and to trap sediments and nutrients, storm water management (SWM) ponds are used extensively (>2000 ponds are in operation within the Greater Toronto Area) across Canada. The ponds have different design features that may influence water quality of pond effluent. Bottom-draw ponds may drain from deeper waters that are cooler in temperature, but may lack dissolved oxygen and have highly elevated levels of chloride both conditions are detrimental to aquatic life. Ponds trap sediment, nutrients, and contaminants within the ponds. Periodic removal of sediment from ponds is necessary to maintain their function, but is also expensive. As a consequence, both pond design and maintenance may be important factors determining conditions within the ponds and how effluent impacts streams and rivers.We will conduct a broad survey of how pond design and maintenance may be impacting the water quality within ponds and the resulting ecological communities that may develop within those ponds, and the impacts of effluent water quality on ecological communities of receiving streams. For example, higher water temperatures and nutrients may contribute to the development of harmful algal blooms that may present health hazards to dogs and children that may frequent SWM ponds. Our work links the ongoing performance of a subset of ponds to determine the impacts effluent has on the receiving streams and rivers. We will examine how pond design and maintenance impacts stream periphyton, benthic invertebrate, and fish communities, including aquatic species at risk, and we will assess cumulative impacts of these ponds given numerous ponds are located and drain into relatively short lengths of many streams. Knowledge gained will allow better design to be incorporated and to determine cost-effective maintenance scheduling that improves efficacy and reduces ecological impact.