Multi-barrier approach & the precautionary principle

Q: I recently heard the terms multi-barrier approach and precautionary principle when doing some research on watershed protection. I was wondering if you could explain what these mean.

A: Using a multi-barrier approach with a precautionary principle philosophy ensures the best quality of water is provided to the end user. In British Columbia, the ecological diversity and multi-jurisdictional nature of watersheds pose challenges that vary from watershed to watershed. For example, in the Comox Valley there are over 30 different water systems drawing from numerous watersheds.

The multi-barrier approach is a process that guides how water is treated from source to tap. The steps include protecting the source, treating the water, maintaining the infrastructure and monitoring the system. An additional barrier to consider is access to the source through licensing. The British Columbia Water and Wastewater Association have indicated that operator training and emergency response planning be included as barriers.

The precautionary principle was a guiding action that developed in Europe in the 1980’s with a focus on limiting one’s ‘footprint’ based on the assumption that harm could occur now or in the future. In the absence of scientific data, the precautionary principle errs on the side of caution, and restricts activity. Watershed protection planning should utilize the precautionary principle when considering potential threats to the watershed. The precautionary principle, when applied to watershed planning, often meets opponents from those who have economic and social interests in a watershed.

In 1999, the Auditor General of BC released the report “Protecting Drinking Water Sources”[1]. The report advocates for province-wide watershed protection while stating that the provincial government is not meeting their responsibility to protect drinking water sources from human-related impacts.

According to the report, a reliable provision of high quality drinking water depends on several levels of protection:

  1. Effective control over land use i.e. water source protection and source selection.
  2. Appropriate water treatment.
  3. Well-maintained water distribution system.
  4. Water quality testing.

In 1999, the Auditor General recommended that the Province designate within government one lead agency for drinking water to coordinate government policy and actions relating to drinking water.

An example of the struggle to protect watersheds used for drinking water is highlighted in the table below. The table is an overview of forest activity in the two largest watersheds in the province. They are both closed to public access now and were lands purchased early in the 1900’s for drinking water purposes.

Table: Timeline of watershed protection in the Victoria and Vancouver watersheds

Year Activity
1897 Land Act establishes watershed reserves
1905 Order in Council protects Crown lands in the Capilano watershed (Vancouver)
1927 999 year lease of Crown lands signed in Vancouver, ensuring protection of the municipal water supply
1930s Capital Regional District of Victoria buys the land in their watershed
1940s Post WWII shift in practice from protected watersheds and no logging to multi-use watersheds
1952 Logging allowed in Victoria watershed
1967 Amendment to Crown lease agreement in Vancouver’s watershed and forest tenures (logging) allowed until 1999
1999 BC’s Auditor General releases Protecting Drinking Water Sources, which investigates drinking water protection by the province and local governments
2001 BC Provincial Health Officer emphasized the importance of the multi-barrier approach, culminating in the Drinking Water Protection Act 2001 and the Action Plan for safe Drinking Water in British Columbia 2002.
2016 Water Sustainability Act and regulations introduced. Watershed sustainability planning one of the key activities.

[1] Available at:

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