Precipitation accumulated over mosquito season (May - August)
The five driest years of Edmonton weather during the past century have all occurred since the year 2000. (Drought of the Century). During this drought period Edmonton has steadily accumulated a net moisture deficit amounting to over 1.5 metres of precipitation below our average levels (Accumulated Precipitation Deficit). This drying trend is echoed in the local groundwater levels that in recent years have plummeted to unprecedented lows (Groundwater Observation Well Levels).
Of course these altered weather conditions have a significant impact on City operations responsible for maintaining Edmonton parkland. For example, staff accustomed to mowing healthy turf have had to shift resources to irrigating sports fields and controlling drought tolerant weeds.
Similarly, as drought stressed trees have declined in health, forestry operations have had to respond by reallocating resources to tree watering programs and increased tree removals (Drought Impacts on the Urban Forest).
One benefit to drier conditions, however has been a decline in Edmonton’s biting mosquito populations and the need for us to control them; along with a corresponding decline in people’s tolerance for them when a few do show up.
During 2011 though, we experienced some of the wettest conditions in recent memory as we returned to more historically normal precipitation levels for our area (Edmonton Precipitation). As a result, mosquito eggs that had collected and remained dormant over the drier years finally hatched, and Edmontonians endured some of the highest levels of mosquito activity experienced in the last couple of decades (Mosquitoes Present vs Past).