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Breaking up pavement seems a tad counter-intuitive in Calgary given the city’s historic infatuation with covering every imaginable surface with asphalt but that doesn’t mean it’s not happening. The “depaving” trend — which started in Portland Oregon as many such trends seem to — is arriving in the city via Green Calgary. The local environmental group has hosted a series of workshops introducing participants to the concept; the jackhammers and crowbars will actually come out this summer.
Such conversations seem to be indicative of a broader shift in thinking about the value of sprawl in the city specifically pertaining to water use and urban runoff. In 2005 the City of Calgary found that 90 per cent of total suspended solids (TSS) ending up in the Bow River arrived via the stormwater system meaning that a vast majority of the sediment in the river comes courtesy of melted snow and rain washing stuff down storm drains.
Carolyn Campbell conservation specialist at Alberta Wilderness Association notes: “If you have a lot of hardened surfaces water runs off really quickly and picks up whatever contaminants or sediments are along the way putting them right in the river.”
Sand salt gravel dirt. Add in the liquids — fertilizers soaps oil grease industrial goop — and the mental picture gets a bit grim. Luckily Calgary has one of the best water treatment systems on the continent so there’s no immediate concern for human health (for instance levels of E. coli — trace amounts of which recently required Winnipeg to institute a citywide boil water advisory — have remained well within acceptable levels over the years notes water quality services manager Nancy Stalker).
But it costs the city a fair bit of coin to keep it that way. Daily sediment contributions to the Bow River have been kept below the 2005 target of 41300 kilograms per day — Shannon Abbott of water resources reports the amount in 2014 was 39520 kg/day — but it required over $140 million to retrofit systems construct drainage areas and scoop out sludge from stormwater ponds in order to get there.
“There’s a lot of costs associated with this” says Abbott. “Such measures take up a lot of space and land that’s of high value. More and more we’re really testing these low-impact development (LID) projects in a Calgary climate and determining their effectiveness.”
LID undertakings — generally lower-cost endeavours that can also beautify an area — harness natural filtration processes to purify runoff: rain gardens green roofs and bioswales are all utilized by the city for such gains. Contrary to goals established in the Municipal Development Plan however impervious surfaces (anything that doesn’t allow for absorption) have grown in percentage of land cover since 1998 a reality complicated by initial costs.
“I think the city’s trying really hard” says Al Sosiak senior limnologist (inland water expert) at Sosiak Environmental Services and former longtime limnologist with Alberta Environment. “But it’s a difficult problem. The more concrete and impervious surfaces you have the more runoff you’re going to get. It’s about building smarter and getting the runoff back into the groundwater as quickly as you can.”
Wetlands — an umbrella term encompassing marshes peatlands and swamps — have long served such a role acting as catchments and filtering runoff. However an estimated 90 per cent of pre-settlement wetlands have been destroyed according to the City of Calgary’s wetland conservation plan a fact Ducks Unlimited’s Craig Bishop says severely impedes load capacity and groundwater cleansing services.
“Anytime you have increasing development they’re lost completely in most cases” says Bishop the organization’s manager of environmental services and education. “Most times they’re still aesthetically there but they don’t function in all the multifaceted ways they would prior to development.”
Bishop notes the province’s recent allocation of $31 million to wetland restoration is an excellent start to mitigating such repercussions although no applications have been approved yet (“I’m sure the government is reviewing every dollar they spend right now” he says). But the province hasn’t exactly done a complete about-face on wetland policy. The impending construction of the southwest ring road for instance will require the filling in of a large portion of wetland on the Tsuu T’ina side.
Lisa Dahlseide executive director of the Weaselhead/Glenmore Park Preservation Society notes that such impacts are doubly troublesome: not only will the wetland services be removed (although the province will be installing stormwater management to take over the role) but urban runoff will likely spill from the ring road into the Elbow River she says.
On one hand the city and province are taking obvious steps towards ensuring cost-efficient water services as the population grows; Paul Fesko of the city’s water resources points out that the city has achieved a “long gradual decline in per capita water consumption” over the past quarter-century. But Calgary has simultaneously sprawled covering or destroying viable ecosystems that have historically filtered water in a sustainable manner.
Sosiak the former limnologist for the province offers a seemingly simple solution to the entire issue: “Build fewer roads use less cars and get around other ways. Manage growth. More people means more wastewater and more development. It sounds like oil is kind of doing that for us right now at least for the next few years but it’s about how we respond to it after that.”
