Goal 2: Protect Interprovincial Groundwater Aquifers

In the PPWB's Strategic Plan, Goal 2 is to protect and sustainably use interprovincial groundwater aquifers*. Sustainable use ensures that this water source can be used by current and future generations as both water quantities and quality of groundwater supplies are protected. If aquifers span Prairie Provincial borders, then the PPWB's role is to facilitate and foster interjurisdictional cooperation and avoid conflicts when aquifers cross borders. The Board would only be potentially involved if groundwater use on one side of the border degrades the amount and/or quality of available groundwater that is on the other side of the border. To date, the Board and the Committee on Groundwater (COG) have not identified any issues of concern for transboundary aquifers. No disputes have arisen. However, a number of collaborative projects have been undertaken by COG over the years to better understand transboundary aquifers. The Board is also considering adding Schedule F to the Master Agreement on Apportionment to provide a framework on how jurisdictions can collectively manage interjurisdictional aquifers by sharing information and resolving potential disputes. This framework would be beneficial if the stressors on transboundary aquifers increase in the future.

For interprovincial aquifers, pumping on one side of the border has the potential to impact quantity of water across the border if drawdown of groundwater levels are reduced in wells on the other side of the border, possibly decreasing well yields and the amounts of groundwater discharge to surface water which maintain spring flow, base flow* in streams, and perhaps seepage area wetlands. Drawdown of groundwater levels may occur for cross-border wells that are supplied by flowing water (artesian conditions), where groundwater users can have access to the water simply by opening of a valve. Also, transboundary deep buried-channel aquifers may be of a concern if heavy pumping from such aquifers on one side of a border results in large drawdown tens of km distant on the other side of the border, thus reducing potential well yields and possibly affecting base flow to surface waters. Extensive and deeply confined sandstone aquifers also extend across provincial borders. For example, the Judith River Aquifer extends beneath the Saskatchewan-Alberta border, and other similar aquifers are located further north. Groundwater supplies from these bedrock formations may be limited by very low recharge rates. For example, movement within and recharge* of the Judith River Aquifer is limited by the highly impermeable shale that lies above this aquifer. Nonetheless, drawdown of several meters and more may be acceptable in deep confined aquifers because wells typically have plenty of water available. In shallower aquifers, well yields may be more sensitive to drawdown as these aquifers may not contain large amounts of available groundwater.

For interprovincial aquifers, quality would only be affected if poor water quality or surface contaminants from one side of the border degrade the quality of groundwater on the other side of the border. Shallow aquifers are more readily contaminated as previously discussed, but these aquifers tend to be small and may only supply water locally. This small scale is less likely to span border or have regional impacts. In contrast, extensive bedrock aquifers cross provincial borders but these deeply confined aquifers typically do not provide suitable drinking water supplies because of their naturally poor water quality, and surface contaminants are less likely to enter the aquifer, unless a deep well has acted as a conduit to degrade the aquifer quality further.

* Glossary:

Aquifer: a geologic formation that is permeable enough to yield useful amounts of water to water supply wells.

Base flow: the flow in a stream that is due to groundwater discharge. Such groundwater discharge is usually continuous year-round, but for small streams transpiration by vegetation along the stream can use up all the base flow in the summer time.

Recharge: process where water from the surface moves down and enters a groundwater aquifer. For an aquifer undisturbed by pumping, the recharge is balanced by discharge of water from the aquifer. Pumping usually induces additional recharge and may reduce the amount of discharge from the aquifer.