Stormwater Reuse – Policy Gaps and Opportunities in Alberta following recent changes to the Water Act and Water (Ministerial) Regulation

  1. Blog
Posted on May 18, 2026 in Feasibility, Reuse, Policy, One Water, STORMR Working Group


Is it time for a Code of Practice for Stormwater Reuse?

At the Bow River Basin Council Legislation and Policy Committee Workshop at the Cochrane Ranche House on February 27, 2026, the ALIDP dove into 20+ years of history to show how activities and policy around stormwater reuse have evolved (or not) and what the road ahead could look like.


Presented by: 

Leta van Duin, B.Sc., Executive Director of the Alberta Low Impact Development Partnership (ALIDP)

Anton Skorobogatov, PhD, Green Infrastructure Senior Specialist at KWL and Vice President of the ALIDP


Photo courtesy Wendell Koning

Recent regulatory changes

While Alberta communities are rightly concerned about water availability, minimum instream flow needs, and long-term resilience, urban development continues to generate large volumes of runoff that must be managed. Recent changes to the Water Act and Water (Ministerial) Regulation do not effectively address the runoff volume topic, but they do tackle some other low-hanging fruit, mainly the addition of a definition of return flow to the Water Act.

Instream flow needs – more than minimums

Participants were reminded of the 2005 Nose Creek Instream Flow Needs Assessment which identified guidance for maximum flows, not just minimums. For small streams, keeping flows near pre-development levels is critical for preserving functionality and protecting nearby infrastructure from damage from increased flows. It is currently the main driver in the Calgary area for stormwater reuse. This is where the concept of Delta Water is used to quantify added flows caused by urbanization.

Delta What?

Delta Water refers to the difference between pre- and post-development evapotranspiration. In practical terms, it identifies the portion of stormwater that is created because the landscape has been urbanized and hardened. If this excess water is understood to be drainage created by development, rather than a diversion of naturally available surface water, then it needs to be treated differently in regulatory practice. Yet outside the interpretation reflected in the Interim Accepted Practice letter (now more than a decade old and applying only to the practice of irrigation in the same catchment), the distinction is scarcely understood or acknowledged.

Irrigation from stormwater – to reduce excess or to reduce potable demand?

The practice of ‘luxuriant’ irrigation as a best management practice to deal with Delta Water and protect streams is not well understood. Reuse is more often framed as a way to reduce potable demand and support fit-for-purpose use. But in our semi-arid region, the goal is not to create landscapes that are generally dependent on irrigation. It is to create landscapes that are drought-resilient, while also able to benefit from excess water when it is available. The City of Calgary’s Irrigation Demand Estimation Tool was developed to quantify upper limits on how much water can be applied in times of plenty without harming plants. This is a complete reversal of an irrigation designer’s usual task and illustrates the excess-management side of stormwater reuse.

Reuse is more than irrigation

Reuse for irrigation is just one practice. Alberta Environment and Protected Areas (AEPA) has now also “fully exempted” dust suppression, sign and bridge washing from a stormwater source. However, the Alberta Public Health Guidelines for Water Reuse and Stormwater Use (Health Guidelines) are silent on sign and bridge washing, and a Quantitative Microbial Risk Assessment will need to be made. On the other hand, the Health Guidelines provide for not only dust suppression but also street sweeping (the latter having not been included in AEPA’s exemption).

A couple of football fields worth of irrigation is not enough

Absolute exemptions were modestly increased from 6,250 m3 to 7,500 m3 in the latest changes to the Water (Ministerial) Regulation.

In practical terms, 7,500 m³ per year is enough to irrigate only about 1.7 hectares, roughly 1⅔ football fields. This falls well short of what is needed to reduce runoff across a subdivision or neighbourhood so, from a stormwater management perspective, there won’t be much in terms of red tape improvement from this adjustment.

A low-energy-release approach will slightly reduce the retention amount needed to protect small streams

A low-energy-release approach from ponds will slightly reduce the amount of runoff-volume reduction that is needed to meet small-stream protection needs, but volume reduction will still be necessary, and irrigation from ponds is still likely to be chosen as a management practice. The specific implications of moving from an annual average runoff approach to a flow duration curve approach (which accompanies a low-energy release approach) were not discussed at the workshop.

It’s the method not the number…“interim” uncertainty

For stormwater managers, an absolute exemption at the Act/ Regulation level does not alleviate the need to provide more certainty for practitioners. The Interim Accepted Practice letter is the only documentation supporting stormwater reuse for irrigation without the need for a diversion license for amounts greater than the exemption. For those in the South Saskatchewan Basin where new diversions are not available, the need for a license represents a dealbreaker, not just an administrative burden.

The lack of permanence of the Interim Accepted Practice along with uncertainty about what the province will do next has already stalled scheduled implementation of more stringent runoff volume targets in, for example, the Nose Creek Water Management Plan. 

Furthermore, because the Crown is responsible for the bed and banks of water bodies, clearer direction on how to protect these features as urban development proceeds is not only warranted and overdue, but necessary to reduce the risk of avoidable harm to the very features the province is charged with safeguarding.

What to do? Is it time for a Code of Practice for Stormwater Reuse?

Stabilizing expectations around stormwater reuse could be achieved through a Code of Practice for Stormwater Reuse. This could formalize the long-standing Interim Accepted Practice while setting out a consistent approach for calculating Delta Water, identifying acceptable modelling assumptions, and documenting compliance. Leveling the playing field in this way would provide clarity for both designers and municipalities and demonstrate the province’s commitment to practical, consistent, and forward-looking water stewardship.

But still, a deprivation mindset

Several comments and questions from the audience still reflected concern about deprivation of downstream users and stream baseflow. This likely reflects how strongly water allocation and baseflow considerations continue to shape thinking in Alberta, as they should, under natural conditions. While the presentation made the case that stormwater reuse supports stream protection and baseflow in the urban context, making that shift in perspective remains counter-intuitive for many.

Rainwater now claimed by the Crown

Workshop participants were keen to discuss the broader definition of water in the latest revision to the Water Act, which includes “precipitation that is intercepted above the ground and captured by works”, commonly referred to in Alberta as ‘rainwater’.

The province’s intent in making this change is not yet clear, beyond explicitly asserting Crown ownership where the Act was previously silent.

While this may be seen as a prudent step to close a potential gap, ALIDP’s view is that rainwater systems are likely to remain largely self-limiting because of storage cost and space requirements, the mismatch between supply and demand timing, the unpredictability of flows, the distributed nature of the resource, and the availability of other regulatory tools to provide clarity.

Other tools include, for example, limits on maximum impervious area (which already exist in land use bylaws), or future restrictions that could limit use to on-site domestic purposes.

Practical learnings from local case studies

Case studies shared from the communities of Okotoks, Calgary, and Chestermere show that Alberta has built up valuable local knowledge over the past decade on stormwater characterization, source control with underground storage for irrigation, natural treatment through large-scale sand filters for disinfection, and related approaches. These examples position us to advance beyond the (by now) relatively familiar territory of stormwater reuse for ornamental landscape irrigation.

Participants were reminded that reuse is not one thing: public health protection, irrigation, and wetland support each involve different objectives and performance targets. Pathogens matter, but so do solids, nutrients, salinity, and other water quality parameters, depending on the intended use.

Dr. Skorobogatov’s contribution to these investigations was warmly acknowledged by the audience.

Unpackaging the Health Guidelines

The Health Guidelines use a log reduction target and log reduction credit framework, creating a practical pathway to combine treatment and exposure controls to achieve the required water quality for different source waters and end uses.

But as any practitioner knows, guidance only becomes useful when it can be interpreted and applied consistently. That is why the ALIDP STORMR Community of Practice is developing interpretive technical guidance documents to support implementation, beginning with Source Water Characterization, led by Dr. Norman Neumann at the University of Alberta School of Public Health. Four more interpretive guidance documents are planned.

This collaborative effort is accelerating the feedback loop between regulators, academia, municipalities, and industry.

Relaxed requirements for spray irrigation

When signage is provided and the system is operated at night, the Health Guidelines no longer require disinfection for spray irrigation from stormwater ponds. Municipalities still need to align to this update. As one participant noted, the absence of disinfection limits the range of potential uses, and tradeoffs associated to this decision should be carefully considered.

Red light, green light

As the range of potential uses expand, what are the practical means to monitor pond withdrawals to ensure going below Delta Water does not occur? It’s one thing to approve an irrigation system, it’s another to have additional bulk withdrawals for newly approved uses, or for future ones that haven’t yet been imagined. Both metering and a green light/ red light water-level approach were put forward as potential options to monitor withdrawals. This will no doubt be the subject of future discussions.

Net licensing

The inclusion of a definition of return flow in the Water Act signals an openness for a net licensing approach. In such a system, the province would still tracks withdrawals and return flows and maintain its existing responsibility for water quality, but municipalities would have flexibility to manage movement of water through an integrated system.

The STORMR group is envisaged as a big tent for discussions on all matters pertaining to a municipal one-water approach.

What next?

The ALIDP presentation closed with a practical but urgent message: now that return flow has been defined, the regulatory runway exists to move forward with a net-licensing approach, supporting the move to a more dynamic, integrated approach to managing our precious water resource. Tools such as a Code of Practice for Stormwater Reuse are urgently needed to de-risk and level the playing field.


Review the slide deck here

 Learn more about participating in the STORMR Working Group

Back to the blog

Related Articles