Long-term Trends in Groundwater Levels in B.C.
Up to 1 million British Columbians are estimated to consume groundwater, and hundreds of groundwater aquifers provide water for industries, municipalities, farms, and rural homeowners in B.C. British Columbia operates a provincial observation well network of over 200 wells, which was established in 1961 to monitor groundwater availability in areas of high human use.
- Observation wells are not used for domestic or commercial use, but instead provide information on groundwater levels over time.
- Monitoring groundwater levels allows us to know how much groundwater is available given human use patterns, weather and climate patterns, and aquifer characteristics.1 Aquifers are geological formations of permeable rock, gravel, or sand containing or conducting groundwater.
- This indicator presents an analysis of long-term trends in groundwater levels recorded at 121 observation wells that have been monitored for ten years or more and that were active as of 2009.
- Groundwater level trends are summarized using three long-term trend categories: Stable or Increasing, Moderate Rate of Decline (3 to 10 cm/year), and Large Rate of Decline (more than 10 cm/year).
It's Called Groundwater!
Provincial Summary of Trends in Groundwater Levels
- Of the 121 examined observation wells, 85% have water levels that are stable or increasing (with 9 wells showing increasing trends), 6% of wells show a moderate rate of decline in water levels, and 9% show a large rate of decline in water levels.
Trends in Groundwater Levels Observed at Observation Wells
- Click or tap on a natural resource region or observation well on the map below to explore trends in groundwater levels.
More About Groundwater Levels
Groundwater levels are sensitive to precipitation, aquifer storage capacity, recharge rate—the rate at which surface water trickles down to refill a groundwater aquifer—and human withdrawal. Groundwater level trends presented here indicate long-term changes in water level, but have not been corrected for changes in precipitation patterns or other factors. Thus, any significant trends are not necessarily directly attributable to human use. However, information on long-term trends can be useful for prompting further research and informing decision-making.
The full methods used to develop this indicator and further statistical results are available in the printable version of this indicator (PDF). The observed long-term trends were categorized using a combination of statistical and environmental significance criteria. Based on both the significance and magnitude of the calculated trend, trends in water levels in wells were classified as exhibiting the following categories:
- Stable or Increasing: the trend was not significantly different from zero or the trend was significantly different from zero with an increasing trend or the trend was significantly different from zero with a declining trend of less than 3 cm per year.
- Moderate Rate of Decline: the trend was significantly different from zero with a declining trend of between 3 and 10 cm per year.
- Large Rate of Decline: the slope was significantly different from zero with a declining trend of more than 10 cm per year.
R package and code: We have developed an R package to facilitate working with, analyzing, and visualizing British Columbia groundwater level data. Download the 'bcgroundwater' package from GitHub. The source code for repeating the analysis presented on this page is also available on GitHub.
References and Other Useful Links
- Visit the Monitoring Aquifers: Provincial Observation Well Network homepage for more information on groundwater monitoring observation wells.
- Groundwater Wells and Aquifers (GWELLS)
- Water Data and Tools for British Columbia
- Previous B.C. State of Environment reports and indicators on groundwater levels in B.C.
- 1Gurdak, J.J., R.T. Hanson, and T.R. Green. 2009. Effects of Climate Variability and Change on Groundwater Resources of the United States. United States Geological Survey. Fact Sheet 2009–3074. (PDF)
*By accessing these datasets, you agree to the licence associated with each file, as indicated in parentheses below.
Updated March 2019
Suggested Citation: Environmental Reporting BC. 2019. Long-term Trends in Groundwater Levels in B.C. State of Environment Reporting, Ministry of Environment and Climate Change Strategy, British Columbia, Canada.