The Supreme Court of Canada has dismissed the appeal in Castonguay Blasting Ltd. v Ontario Environment.1 Justice Abella writing for a unanimous Court writes:
 Ontario's Environmental Protection Act, RSO 1990, c. E. 19 ("EPA"), requires that the Ministry of the Environment be immediately notified when a contaminant is discharged into the environment. There are two pre-conditions to this reporting requirement — the discharge must have been out of the normal course of events and it must have had — or was likely to have — an adverse environmental impact. The purpose of the requirement is to let the Ministry know about potential environmental damage so that any consequential remedial steps can be taken in a timely way.
 The interpretive exercise engaged in this appeal is to determine when the reporting requirement is triggered. In my view, there is clarity both of legislative purpose and language: the Ministry of the Environment must be notified when there has been a discharge of a contaminant out of the normal course of events without waiting for proof that the natural environment has, in fact, been impaired. In other words: when in doubt, report.
company fails to report discharge of rock debris to MOE
The circumstances giving rise to charges by the Ministry for failing to report the "discharge of a contaminant into the natural environment" contrary to s. 15(1) of the EPA, involved a subcontractor conducting blasting operations for a highway-widening project in Marmora, Ontario.
One rock blasting operation went awry causing rock debris to be propelled approximately 90 metres in the air, crashing down through the roof of a home and damaging a car. The subcontractor reported the incident to the contract administrator, who in turn reported to the Ministry of Transportation and the provincial Ministry of Labour. However, no report was ever made to the Ministry of the Environment, which only learned indirectly some 5 months later.
contaminant discharges must be reported promptly without waiting for proof of impairment
The Court's analysis is clear and unequivocal:
 ... as this Court recognized in Canadian Pacific, environmental protection is a complex subject matter — the environment itself and the wide range of activities which might harm it are not easily conducive to precise codification ... . As a result, environmental legislation embraces an expansive approach to ensure that it can adequately respond "to a wide variety of environmentally harmful scenarios, including ones which might not have been foreseen by the drafters of the legislation" ... . Because the legislature is pursuing the objective of environmental protection, its intended reach is wide and deep … .
 The issue in this appeal is the proper interpretation of the reporting requirement in s. 15(1). This provision states:
15.— (1) Every person who discharges a contaminant or causes or permits the discharge of a contaminant into the natural environment shall forthwith notify the Ministry if the discharge is out of the normal course of events, the discharge causes or is likely to cause an adverse effect and the person is not otherwise required to notify the Ministry under section 92.
 ... The purpose of the reporting requirement in s. 15(1) is to ensure that it is the Ministry of the Environment, and not the discharger, who decides what, if any, further steps are required. When a contaminant is discharged, the discharger may not know the full extent of the damage caused or, in the words of s. 15(1), likely to be caused. Moreover, many potential harms such as harm to human health, or injury to plants and animals, and even impairment of the natural environment, may be difficult to detect without the expertise and resources of the Ministry. As a result, the statute places both the obligation to investigate and the decision about what further steps are necessary with the Ministry and not the discharger.
 Notification provides the Ministry with the opportunity to conduct an inspection as quickly as possible and to obtain information in order to take any necessary remedial action and to fulfil its statutory mandate. This enables the Ministry to respond in a timely way to the discharge of a contaminant into the natural environment and to be involved in determining what, if any, preventative or remedial measures are appropriate.
 As the interveners Canadian Environmental Law Association and Lake Ontario Waterkeeper pointed out in their joint factum, s. 15(1) is also consistent with the precautionary principle. This emerging international law principle recognizes that since there are inherent limits in being able to determine and predict environmental impacts with scientific certainty, environmental policies must anticipate and prevent environmental degradation (O. McIntyre and T. Mosedale, "The Precautionary Principle as a Norm of Customary International Law" (1997), 9 J. Envtl. L. 221, at pp. 221-22; 114957 Canada Ltée (Spraytech, Société d'arrosage) v Hudson (Town), 2001 SCC 40,  2 SCR 241, at paras. 30-32). Section 15(1) gives effect to the concerns underlying the precautionary principle by ensuring that the Ministry of the Environment is notified and has the ability to respond once there has been a discharge of a contaminant out of the normal course of events, without waiting for proof that the natural environment has, in fact, been impaired.
 Parsing the language of s. 15(1) illuminates its clear preventative and protective purposes. First, a person must discharge a contaminant. Second, the contaminant must be discharged into the natural environment. Third, the discharge must be out of the normal course of events. Fourth, the discharge must be one that causes or is likely to cause an adverse effect. Finally, the person must not be otherwise required to notify the Ministry under s. 92, which refers to the spill of pollutants from a structure, vehicle or container and is therefore not applicable to the circumstances of this case.
 Castonguay advocates that we adopt the minority approach of Lamer C.J. in Canadian Pacific. This, with respect, is an argument that cannot survive the amended language in the EPA after Canadian Pacific was decided. The most significant change to the EPA was the creation of a separate statutory definition of "adverse effect". The definition included the words "means one or more of" the eight components set out in (a) through (h). None of these components is said to be an overriding requirement, and each is stated to be an adverse effect. As a result, all eight branches of "adverse effect" provide independent triggers for liability. Castonguay's interpretation reads out these crucial legislative directives that each effect is deemed to be adverse.
 To interpret "adverse effect" restrictively not only reads out the plain and obvious meaning of the definition, it narrows the scope of the reporting requirement, thereby restricting its remedial capacity and the Ministry's ability to fulfill its statutory mandate.
 In summary, the requirement to report "forthwith" in s. 15(1) of the EPA is engaged where the following elements are established:
- a "contaminant" is discharged;
- the contaminant is discharged into the natural environment (the air, land and water or any combination or part thereof, of the Province of Ontario);
- the discharge is out of the normal course of events;
- the discharge causes, or is likely to cause, an adverse effect, namely one or more of the effects listed in paragraphs (a) to (h) of the definition;
- the adverse effect or effects are not trivial or minimal; and
- the person is not otherwise required to notify the Ministry under s. 92, which addresses the spill of pollutants.
reporting to one government agency is not notification to all
Apart from clarifying the independent triggers for reporting obligations under s. 15(1) of the EPA, perhaps the most striking reminder to private business is that a single work incident can give rise to statutory duties to notify multiple regulators. In this case, Castonguay's notification to the highway project contract administrator, who in turn reported to the Ministry of Transportation and Ministry of Labour, was not deemed to be notification to all government regulators.
This means that business managers must be organized and keep available the contact information for all relevant regulatory authorities so that when an incident occurs, they can notify the appropriate agencies as quickly as possible. The Supreme Court has underlined that it is not acceptable to delay reporting and instead "wait and see" whether adverse effects actually cause significant environmental impairment.