Water availability concerns are not intuitively associated with Metro Vancouver. Although the coastal climate brings an average of over 1100mm of annual rainfall, 80% of this falls during the rainy winter season, making the growing season relatively dry . As a result, the high productivity of the agricultural industry is dependent on the availability of water for irrigation. Water sources include streams, groundwater and, in a few cases, domestic water.
The following outlines how improving the understanding of the irrigation demand for agricultural production is a crucial step toward strategically managing the water resources upon which the agricultural industry depends.
Expansion of irrigated area and increased future competition among water users at the urban fringe set the stage for potential increases in demand. Simultaneously, climate change has the potential to both increase irrigation demand and reduce water availability.
Regional climate change projections developed by the Pacific Climate Impacts Consortium (PCIC) for the Metro Vancouver estimate the region will experience increased growing season temperatures and evaporation rates in combination with reduced summer precipitation and winter snowfall . As such, climatic changes have the potential to both increase irrigation demand and reduce water availability by extending the growing season and by decreasing stream flow and groundwater recharge. Sea level rise and associated increases in salinity could further reduce the availability of quality water for irrigation.
There is uncertainty regarding the sustainability of current extraction practices, which limits the ability to manage water resources in times of water stress.
A number of water resource management concerns in Metro Vancouver result from legislative gaps and an absence of monitoring . While surface water licenses in Metro Vancouver are highly regulated, records of actual water use are poor. The Water Act in BC requires surface water users to obtain a license from the Water Stewardship Division of the Ministry of Environment. While licenses provide maximum allotments, there is little to no monitoring of actual extraction. Consequently there is large uncertainty regarding the sustainability of current extraction rates and irrigation practices.
Groundwater is a significant source of irrigation water for some growers in Metro Vancouver . In contrast to highly regulated surface water, historically, groundwater use in BC has gone largely unregulated . This is due to both a lack of understanding of groundwater dynamics and a lack of groundwater monitoring. Groundwater under the current Water Act can be extracted for irrigation and other purposes without a license . The new Water Sustainability Act–coming into force in 2016– addresses this concern by introducing licensing for groundwater use.
There is additional uncertainty regarding the extent of current groundwater reserves, although declining water levels have been detected in some of the more highly used aquifers, such as the Hopington and Aldergrove aquifers in Langley . Additionally, nitrate contamination from agricultural production has presented considerable concern for water quality and environmental and human health . Uncertainty of groundwater reserves, combined with evidence of drawdown and contamination create risk for future allocation of crucial water resources.
Further uncertainty regarding water availability exists by the fact that water allocation and licensing systems give little consideration to surface-groundwater interactions, which are poorly understood in practice . These two sources are treated as distinct, despite the potentially important effects of groundwater extraction on surface water flow . Over-extraction from aquifers has been identified as a cause of diminishing groundwater levels that can reduce stream baseflow .
The development of water management policies to address these concerns requires an improvement in our understanding of irrigation demand for agricultural production: An important step toward strategically managing the crucial water resources upon which the agricultural industry depends and establishing security within the sector.
The following section, Project Goals, will outline the specific questions addressed in this assessment.