Water Stewardship Information Sources
| Citation | Bull, J. 2009. Assessment of stormwater quality and snowmelt runoff in Whistler Creeks, 2007-2008. BC Ministry of Environment. |
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| Organization | Ministry of Environment |
| URL | http://www.env.gov.bc.ca/epd/regions/lower_mainland/water_quality/reports/whistler-creek/pdf/whistler-creeks-2007-08.pdf |
| Abstract/Description or Keywords | The British Columbia Ministry of Environment (MoE), in partnership with the Resort Municipality of Whistler (RMOW), conducted water quality monitoring programs in three urbanized Whistler watersheds during stormwater (October 2007) and snowmelt (May 2008) runoff periods. This partnership was viewed as beneficial to both parties, as overlapping internal goals of each organization were clearly identified from the outset. For RMOW, their Whistler 2020 goals included a commitment to effective stormwater management. For MoE, effective stormwater management is a regulatory requirement for RMOW under their updated 2004 Liquid Waste Management Plan (LWMP). This joint stewardship approach to stormwater management was thus initiated to compliment the regulatory approach addressed under the LWMP. The studies, partially funded by RMOW, involved joint field coordination and monitoring, as well as reporting to both the Resort Municipality and the Ministry. Whistler waterbodies may be at risk from urban rainwater and snowmelt runoff, as storm sewers convey water and potential pollutants directly into ditches, stormwater ponds, and streams, which ultimately lead to larger creeks and lakes that have high fisheries and recreational values. Common contaminants in both types of runoff include nutrients, bacteria, metals, hydrocarbons, and suspended sediments. Additional contaminants in snowmelt runoff include potential components of road salt: chloride, ferrocyanide (anti-clumping agent), urea (ammonia), and trace elements, or impurities (mostly phosphorus, sulphur, nitrogen, copper and zinc). The goal of both the storm event and snowmelt studies was to determine whether land use and winter road maintenance practices in the Whistler, Crabapple, and Fitzsimmons Creek watersheds were leading to water quality impacts in downstream locations. As part of RMOW’s stormwater management plan, Whistler Village runoff is first directed to a 100-m long biofiltration pond along Blackcomb Way just north of the Village. An additional goal of the overall water quality assessment was to assess water quality in the biofiltration pond and its discharge during periods of high runoff, and to determine the pond’s effectiveness in removing potential pollutants during these periods. Findings of the rainwater quality study in Whistler (Section 3.0), Crabapple (Section 4.0), and Fitzsimmons Creeks (Section 5.0) showed that they were all receiving non-point source pollution during periods of high runoff that was primarily caused by high suspended sediment and turbidity levels during the first two weeks of October 2007. Sediment-associated copper, iron and zinc levels were also elevated in lower creek reaches and at times exceeded British Columbia Approved Water Quality Guidelines (B.C. AWQGs) for the protection of aquatic life. Activities in the Whistler and Crabapple Creek watersheds, including yearly summer service road maintenance, the 2010 Winter Olympic ski run construction in 2006/07, and bike park operation on Whistler Mountain, all likely contributed to the observed turbidity and sediment levels in October 2007. Excessive turbidity indicates significantly impaired conditions for clear water fishes, which can reduce fish growth rate, habitat size, or both. Significant sources of suspended sediments in Fitzsimmons Creek are likely originating from the Fitzsimmons Slip, although urban runoff from the Whistler Village and further downstream neighbourhoods are contributing elevated levels of both sediments and associated metals during periods of high runoff. Findings of the snowmelt study (Section 6.0) showed that snowmelt runoff contributed to elevated levels of chloride, some metals, and turbidity to creeks in urban areas. Whistler and Fitzsimmons Creeks appeared to be relatively well buffered from snowmelt runoff impacts, as heavy metal and sediment concentrations increased minimally in downstream locations. Crabapple Creek, however, with nearly 30% of its natural drainage arising from stormwater drainage, appears to be more affected by either the high flows associated with snowmelt or practices such as snow storage within its stream banks along lower reaches. Elevated levels of turbidity, cadmium, copper and zinc were observed in Crabapple Creek throughout May 2008, which exceeded B.C. AWQGs at times and were likely derived from sediment and road sources. Additionally, snowmelt runoff from the snow storage area in Day Lot 5 had particularly high levels of suspended sediments, copper and iron. Copper was also found to be elevated in leaching tests of the raw road salt and sand material used in winter road maintenance, which may be contributing low level, but chronic, guideline exceedances in Whistler waterways. Findings of the biofiltration pond monitoring study (Section 7.0) showed that the pond was receiving pollutants from urban stormwater runoff that exceeded B.C. AWQGs at times. Elevated levels of suspended sediments, turbidity, E. coli, and metals (cadmium, copper and zinc) were observed during periods of high runoff, i.e. first flush events and early snowmelt runoff. Ammonia was also elevated during the snowmelt period, likely due to the use of urea in the road salt mixture. In October 2007, the biofiltration pond was particularly effective in reducing higher levels of suspended sediments and associated metals (total copper, iron and zinc), while turbidity was only somewhat effectively removed. In May 2008, total copper was effectively reduced and there was some evidence that turbidity, total iron, nitrate and total phosphorus were effectively reduced. Conversely, cadmium and lead did not appear to be effectively removed by the pond in May 2008. The pond was not as effective in removing turbidity, total Fe and total Zn during the snowmelt period, likely due to the relatively lower levels of these parameters compared to the stormwater period of October 2007. Recommendations to improve water quality during both runoff periods included conducting evaluations of current erosion and sediment control measures on summer maintenance roads and the bike park on Whistler Mountain, in particular. Completion and evaluation of re-vegetation following Creekside soil disturbance in 2006/07 was also recommended prior to September 1, 2008. Optimization of source controls in neighbourhoods surrounding Whistler creeks and the biofiltration pond is also recommended, so that the impact of urban stormwater runoff can be minimized. Examples of source control can include low-impact development (LID) and increased infiltration. Additional recommendations to improve water quality during snowmelt periods included using only appropriate amounts of road salt and sand, as well as avoiding storage of excess snow near or within stream banks, the biofiltration pond, and Day Lot 5 (due to its proximity to Fitzsimmons Creek). Recommendations to improve the biofiltration pond’s ability to remove contaminants during high flow periods were to conduct upgrades, if necessary, as well as to periodically remove and properly dispose of accumulated sediment from the sediment deposition area at the inlet of the pond. |
| Information Type | report |
| Regional Watershed | Howe Sound & Sunshine Coast |
| Sub-watershed if known | Fitzsimmons Creek, Crabapple Creek |
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| Project status | complete |
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