Stormwater / Snowmelt Runoff Impact Reduction Initiative for Small Prairie Urban Communities Project
The Assiniboine Watershed Stewardship Association recently partnered with the Saskatchewan Watershed Authority and the City of Yorkton to determine the impact of the city’s stormwater and snowmelt runoff on the Assiniboine River Watershed. Along with our partners, financial support has also been provided by Environment Canada's EcoACTION Community Funding program.
The Storm Water Study – An Overview
What are the potential impacts of Yorkton’s runoff? The goal of the three year study was to determine the associated risk to waters receiving runoff from small prairie urban communities. The study specifically focused on assessing pollutants in Yorkton’s stormwater runoff. Runoff from stormwater and snowmelt is a contributing factor in urban pollutants reaching surface waters (i.e. Yorkton Creek, Assiniboine River). Commonly, urban runoff pollutants include pesticides, fertilizers, paints, various petroleum products, sediment, and enteric bacteria. Water quality samples were collected during significant snowmelt/ rainfall events at 3 strategic locations throughout the city.
A total of 68 water quality parameters were tested from the following categories: nutrients, ions, metals, sediment, pH, alkalinity, total coli forms, E. coli, petroleum products, chemical oxygen demand and biological oxygen demand.
What pollutants are in Yorkton’s water runoff? Monitoring pollutants in Yorkton’s runoff...
The monitoring program began with the spring snowmelt of 2009. Samples were collected during the spring snowmelt season and during significant rainfall runoff events.
Water quantity and quality samples were collected at three strategic points within the City of Yorkton. There are variations in the type of runoff at each site – residential, commercial, and mixed. A sampling site by the Exhibition Grounds monitored residential runoff. A site by Walmart monitored commercial/parking lot runoff. A third site, on Victoria Street, monitored a mixture of residential and commercial runoff.
All parameters tested were within acceptable limits except for the concentrations of three heavy metals (copper, lead, and zinc), which exceeded the provincial surface water objectives for the protection of aquatic life and were also higher than concentrations measured at the Prairie Provinces Water Board monitoring site on the Assiniboine River at Kamsack, SK.
Major potential sources of copper in urban runoff include brake pads, vehicle tires, materials washed from building siding and urban soil. Sources of lead include gasoline additives, tire wear, and old leaded paint. Zinc is commonly used in galvanized metals (such as ducts an equipment boxes). In addition, both motor oil and hydraulic fluid contain high concentrations of zinc. As a result, sites such as parking lots and streets can be potential sources for these 3 metals.
How is the City of Yorkton Managing Stormwater? (The LOGAN GREENS PROJECT)
In response to the extreme flooding that occurred in Yorkton on July 1, 2010, which was partly caused by an overwhelmed stormwater drainage system, the AWSA is contributing to the stormwater management component of a major development being constructed by the City of Yorkton in the city’s south region, the Logan Greens Project.
The Logan Greens stormwater ponds are being constructed east of Yorkdale school, adjacent the community gardens. The ponds are part of the overall Logan Greens eco-recreation area being constructed by the City of Yorkton to showcase how “backwash waste water” from the city's new water treatment plant can be treated, managed, and utilized in an aesthetically pleasing, environmentally beneficial manner (through natural filtration via a series of constructed settling ponds, stream channels and wetlands). Backwash waste water is the water discarded from cleaning of the filter system at the water treatment plant. The stormwater ponds will accept surface drainage from the area of the city located around the traffic circle as well as parts of Logan Crescent. The ponds are considered “dry ponds”, meaning the gradually sloped ponds will hold water only during storm events.
The purpose of the ponds are two-fold, providing both stormwater quantity and quality management. They store water allowing it to drain in a slower, controlled manner, in addition to allowing the water time to settle. The settling causes silt, debris and contaminants to accumulate on the bottom of the pond. The vegetation seeded in the pond could potentially absorb those contaminates. From the ponds, the purified water will flow in a pre-existing overland channel that joins to a newly constructed stream flowing from the new water treatment settling ponds, eventually making its way into a newly constructed public fish pond.
Estimated cost of the stormwater ponds is $151,200 with an expected completion date of August 2012.
The city is currently working on two other stormwater retention pond projects: the Brodie Ave and Dracup Ave stormwater management projects.
*** SEE ATTACHMENT AT THE BOTTOM OF THE PAGE FOR A DESIGN PLAN DIAGRAM OF THE LOGAN GREENS PROJECT ***
Yorkton July 1st, 2010 Canada Flood - Interactive Photo Map
2010 was one of the wettest years in history for the Assiniboine River Watershed. Despite a spring that saw very little runoff, empty dugouts, and the possibility of drought looming on the horizon, the yearly average watershed precipitation value of 450 mm was drown by the huge rainfalls experienced this past summer! Perhaps hardest hit of all was the city of Yorkton which experienced a devastating storm July 1st that caused widespread flooding throughout the city, with an estimated 70% of homes being affected.
Environment Canada recorded 64 mm of rainfall before midnight while they said that some areas of the city experienced up to 150 mm of rain! The AWSA’s Storm Water Study rain gauges recorded over 80 mm… either way, the July 1st event was the highest recorded rainfall since July 10, 1953 when it rained 95.3 mm!
Click the file at the bottom of the page for an interactive map of photos taken around Yorkton July 1st and 2nd, 2010. (All photos were compiled from publically available Yorkton Flood Facebook page).
Directions: Start the slide show. Click on a number from the City Map to see a picture taken at that location during the flood. Then click on the "HOME" icon in the lower left corner of the slide to go back to the City Map.
Funding support for this Assiniboine Watershed Stewardship Association, Stormwater/Snowmelt Impact Reduction Initiative project is provided by:
