Executive Summary: Key Legal and Evidentiary Issues

• The City of Abbotsford's failure to close the Barrowtown Pump Station floodboxes allegedly permitted Fraser and Vedder River water to flood the Sumas Prairie in November 2021.

• Certification of the class action under s. 4(1) of the Class Proceedings Act was challenged on five grounds: methodology, Inner/Outer Prairie conflict, private nuisance, public nuisance, and Indemnity Class conflicts.

• Expert hydrotechnical evidence from Brian LaCas proposed a plausible methodology using 2-D hydraulic modelling to assess the impact of open floodboxes on flood levels and damage, which the Court of Appeal upheld as realistic and grounded in available data.

• Alleged conflicts between Inner Prairie and Outer Prairie residents were found to be illusory, as no class member would logically argue that open floodboxes were beneficial rather than harmful.

• Approximately 400 properties carried indemnity covenants obligating owners to hold the City harmless from flood claims, creating unresolved conflicts and risks of cost liability for those class members.

• Certification of the Indemnity Class subclass was set aside and remitted to the trial court because the chambers judge failed to establish a workable plan addressing the enforceability of the covenants and the exposure of Indemnity Class members to substantial costs.

The Sumas Prairie flood and the origins of the class action
The Sumas Prairie, located in the Abbotsford area of British Columbia, is a floodplain that historically formed a 40 square-kilometre lake, which was eventually drained for agricultural and flood-control purposes. The Sumas Dike runs along the southeast side of the Prairie, protecting the area east of the dike (the "Inner Prairie") but not the area west of the dike (the "Outer Prairie"). The Barrowtown Pump Station, managed and operated by the City of Abbotsford, continuously drains the Prairie through four floodboxes that regulate the flow of the Sumas, Vedder, and Fraser Rivers. Under the station's operating procedures, the floodboxes must be closed when the water level on the Fraser River side exceeds 3.0 metres to prevent flooding of the Outer Prairie.
On November 13, 2021, two atmospheric rivers brought intense rainfall to the Abbotsford area and parts of Washington near the British Columbia border. By the morning of November 14, 2021, the water level on the Fraser River side rose above 3.0 metres. Despite this, the Pump Station floodboxes were left open and remained open until late morning on November 15, 2021, by which time the water level on the Fraser River side had reached a height of 6.87 metres. During that interval, water from the Fraser and Vedder Rivers flowed through the open Pump Station floodboxes into the Outer Prairie. On November 16, 2021, the Sumas Dike overtopped and gave way in two places, causing water to flow into and flood the Inner Prairie. There was extensive damage and loss occasioned to residents and owners of property in the Sumas Prairie.

The class proceeding and its legal foundation
On December 23, 2021, a claim was brought under the Class Proceedings Act, R.S.B.C. 1996, c. 50 on behalf of the affected residents and property owners against the City, Fraser Valley Regional District, the Province of British Columbia, and others. The principal allegation of fault in the initial notice of civil claim was that the defendants had failed to warn residents and property owners in a timely manner of an imminent flood, preventing them from taking steps to protect and preserve their property. The pleadings were amended twice prior to the certification application, and in their final form focused upon a single fault: the City's failure to close the floodboxes when the height of the Fraser rose above the critical level. The last amended notice of civil claim was framed in negligence, gross negligence, public nuisance, and private nuisance.

The certification decision at first instance
The certification application was heard on April 22–26, 2024. The chambers judge found that the duty of care alleged had been recognized in analogous categories of cases, including the flooding cases of Pisclevich v. Manitoba and Anderson v. Manitoba. He was satisfied the claims relied on long-accepted causes of action framed in negligence and nuisance. He also considered the pleadings to have adequately described a relationship of causation, proximity, and foreseeability of damages, and accordingly held that a cause of action was sufficiently pleaded. On nuisance, the judge similarly held the pleadings made the necessary allegations supported by material facts justifying causes of action in both public and private nuisance. He identified an identifiable class of residents or owners of 1,423 properties in the areas that lie in the floodplain, which included the Vedder Canal, the Barrowtown Pump Station, as well as the Outer and Inner Prairie. The judge certified a series of common issues including the cause of the Sumas Flood, whether the City caused or contributed to the extent of the flood, the City's duty of care and standard of care in operating and staffing the Barrowtown Pump Station, and questions of damages, aggregate damages, and punitive damages. He addressed the City's submission that an intractable conflict existed between Outer Prairie and Inner Prairie residents, concluding there was no conflict as it related to the City's duty of care in its operation of the Pump Station, though there might be a conflict on the question of damages.

The indemnity covenants and the Indemnity Class
Approximately 400 of the 1,423 properties (about 28%) impacted by the flood had a flood covenant with an indemnity provision registered against title (the "Indemnity Class"). These covenants obliged owners to hold harmless and indemnify the City against claims for loss or damage caused by flooding, including a provision that the owner would not sue, claim damages from, or hold the City responsible or liable for any such loss or damage, and would indemnify the City from and against all expenses and costs, including legal costs on a solicitor/client basis. To address the potential conflict, the chambers judge ordered the creation of subclasses for the Indemnity Class, required separate legal counsel, and granted leave to later identify representative plaintiffs. On June 17, 2025, Oranya Farms II Holdings Inc. was named as representative plaintiff for the Outer Prairie Indemnity Class, and Western Turf Farms Ltd. was named as representative plaintiff for the Inner Prairie Indemnity Class. However, on being advised that these representative plaintiffs had in fact entered into agreements protecting them from liability to pay any costs until the enforceability of the covenants is determined — a save harmless agreement between the representative plaintiffs and counsel that had not been earlier disclosed — counsel for the City indicated a different argument with respect to conflicts would have been made. The chambers judge declined to revisit the order.

The City's appeal and the five grounds of error
The City of Abbotsford appealed to the British Columbia Court of Appeal, seeking to establish five errors: (1) insufficient methodology for resolving common issues, particularly the inability to distinguish flooding caused by the open floodboxes from flooding originating from the Nooksack River; (2) a conflict of interest between Inner and Outer Prairie residents on the common issues; (3) the pleadings failing to disclose a cause of action in private nuisance; (4) the pleadings failing to disclose a cause of action in public nuisance; and (5) unresolved conflicts arising from the Indemnity Class covenants.

The Court of Appeal's analysis of the methodology
The Court of Appeal, in reasons written by Justice Willcock and concurred in by Justices Riley and Edelmann, rejected the City's challenge to the methodology. The class members had adduced the expert opinion of Brian LaCas, a hydrotechnical engineer, who proposed using a numerical hydraulic model such as the Storm Water Management Model (SWMM) to assess the impact of open floodboxes on flood levels and area flooded. Mr. LaCas's proposed methodology involved standard numerical 2-D hydraulic modelling of the Fraser River, Sumas River, floodbox operations, and the Sumas Prairie, and his first report described a comprehensive review of literature including many US sources of data with respect to the Nooksack River. The Court noted that Mr. LaCas explicitly referred to modelling of the Sumas River, the conduit by which the Nooksack River flooding entered the Sumas Prairie, and that his opinion was not offered in support of a sole source theory. The City had chosen not to cross-examine Mr. LaCas on his methodology, and the Court held it was open to the chambers judge to conclude the methodology was realistic and grounded in fact, supported by extensive data sources including river gauge data, US and Canadian hydrological studies, and SCADA data from the Barrowtown Pump Station.

The alleged conflict between Inner and Outer Prairie residents
The Court of Appeal agreed with the chambers judge that the conflict between Inner and Outer Prairie residents was entirely illusory. No class member in a class action alleging that the failure of the City to close the floodboxes caused flood damage would logically wish to advance the theory that the open floodboxes were a blessing, rather than a curse. While the City argued that the breach of the Sumas Dike may have led to the drainage of the Outer Prairie, lessening the damage that would have occurred had the dike held fast, the Court found this argument did not give rise to conflicting interests between class members on the common issues. The chambers judge was correct to conclude there might be a conflict on the question of damages but no conflict as it related to the City's duty of care in its operation of the Pump Station.

Private and public nuisance claims upheld
On private nuisance, the Court held it was not plain and obvious that the claim had no reasonable prospect of success. Unlike in Lebourdais v. British Columbia, where the pleadings specifically alleged a failure to take steps to abate a nuisance, the present pleadings alleged a duty to operate and staff the Barrowtown Pump Station in a reasonable and prudent manner, and that the floodboxes were negligently left open. The Court noted the class members' case may be said to be founded upon misfeasance as much as nonfeasance. On public nuisance, the Court found the class members had adequately addressed the "special damage" requirement. The chambers judge had concluded there was evidence the flooding interfered with access to public roads and bridges, an elementary school, air quality, and a water main. The class members' pleadings identified a subclass of persons who claimed to have suffered personal injury and/or damage to personal and/or real property that differed in degree and kind from the harm experienced by all who suffered the effects of the interruption of public services arising from the flooding of the Sumas Prairie.

The Indemnity Class certification set aside
The Court of Appeal found the chambers judge erred in certifying the proceeding brought on behalf of the Indemnity Class. The Court identified several unresolved problems: no workable method had been produced for addressing the enforceability of the indemnity covenants on behalf of all class members before certifying the class proceeding; the representative plaintiffs were not themselves exposed to liability for costs by agreement with counsel, placing them in a different position from the Indemnity Class members they purported to represent; and there was no proposal before the chambers judge to address how opting out would work. There was also no plan to have the enforceability of the covenants determined as a common issue, nor did the chambers judge certify such a common issue. The Court noted this was a situation where the parties were aware of no case in which a class proceeding had been certified in circumstances where participation carried a significant risk of exposure to liability for costs, and that careful attention must be paid to the notice to prospective class members, to the timing of opting out, and perhaps to defining the Indemnity Class in a manner that effectively requires opting in.

The ruling and outcome
The British Columbia Court of Appeal allowed the appeal in part. The certification of the class action as it pertained to the main class — including the negligence, private nuisance, and public nuisance claims — was upheld. However, the certification of the proceeding brought on behalf of the Indemnity Class was set aside, and the appointments of Oranya Farms II Holdings Inc. and Western Turf Farms Ltd. as representative plaintiffs for the Indemnity Class were vacated. The application for certification as it relates to the Indemnity Class was remitted to the trial court for reconsideration. The successful parties on the main certification issues were the respondents (the class members), while the City of Abbotsford succeeded on the Indemnity Class issue. No specific monetary amount was awarded or ordered at this stage, as the proceeding remains at the certification phase and the merits of damages have yet to be determined.