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 180 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 a statistical analysis of long-term trends in groundwater levels recorded at 119 observation wells that have been monitored for ten years or more and were active as of 2004.
- 78% of observation wells examined have water levels that are stable or increasing (with 4 wells showing increasing trends); 9% of observation wells show a large rate of decline in water levels (more than 10 cm per year), with a further 13% of wells showing a moderate rate of decline in water levels (between 3 and 10 cm per year).
It's Called Groundwater!
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.
Tip: Click or tap on the wells on the map below to see details of each well.
Tips for exploring the interactive charts:
- The bottom plot (called a "hydrograph") shows the monthly groundwater levels for the history of the well, with the orange line representing the calculated trend in annual average groundwater levels. The slope and significance of the trend are given below the title.
- The graph to the right of the map shows the monthly groundwater levels relative to the annual average. This illustrates the seasonal nature of water levels recorded in that well; many wells will have higher than average water levels in the spring, and lower than average levels in the late summer and fall. The shaded blue area shows the range of variation within which 90% of observations in that month fall. Orange dots show the groundwater levels in the most recent 12 months since the date of analysis.
- Hovering your mouse over a particular month on the upper chart will cause black dots to appear on the time-series (bottom) chart. These represent the groundwater levels for the selected month in each year along the time series.
- Hovering your mouse over a particular year on the hydrograph (bottom chart) will cause black dots to appear on the upper chart. These dots represent the monthly groundwater levels of the selected year, relative to the yearly average.
R package and code: We have developed an R package to facilitate working with, analysing, and visualising British Columbia groundwater level data. Download the 'bcgroundwater' package from GitHub. The source code for repeating the steps involved in processing the raw data (available from the Groundwater Observation Well data access tool) to make it suitable for analysis and repeating the analysis presented on this page is also available on GitHub.
References and Other Useful Links
- Visit the Provincial Observation Well Network homepage for more information on observation wells including data downloads, detailed well reports and observation well photos
- WELLS - Ground Water Wells and Aquifer Database
- B.C. Water Information and Tools
- Wei, M., D. Allen, A. Kohut, S. Grasby, K. Ronneseth, et al. 2009. Understanding the Types of Aquifers in the Canadian Cordillera Hydrogeologic Region to Better Manage and Protect Groundwater. Streamline Water Management Bulletin 13(1): 10-18. (PDF)
- 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 June 2014