Lessons from Walkerton – Regulating Manure Risks
The e-coli contamination of Walkerton’s water supply in May, 2000 which resulted in the illness and death of many Walkerton residents appears to have originated from a livestock operation proximate to the town’s wells. Evidence heard by The Walkerton Inquiry indicates that this contamination occurred despite compliance by the livestock operation with present guidelines and best management practices concerning manure storage and spreading. What is the possibility of similar well contamination elsewhere? Is present manure management regulation sufficient to address this risk? If not, how should manure management be regulated to protect drinking water supplies?
A coalition of rural landowner groups concerned about manure management issues and the Sierra Club of Canada (the Alert-Sierra Coalition) has recently argued before The Walkerton Inquiry that present manure management guidelines and best practices are inadequate to protect Ontario’s surface and groundwater resources and that a systematic, coordinated risk-based approach to manure management regulation is required for the protection of this resource.
Studies presented to the Inquiry have established that over 150,000 wells in Ontario may be contaminated by bacteria in excess of maximum acceptable levels established under the Ontario Drinking Water Objectives. These studies indicate that this contamination results twice as frequently in fields where manure is routinely applied. Evidence heard by the Inquiry also indicates that the pathogens contained in the manure may survive in the soil for months or years and may travel through the soil to enter underground aquifers many kilometers from their point of origination.
The position of Alert-Sierra is that, even where mandated by municipal bylaw, nutrient management plans are ineffective to prevent manure contamination of water resources because they focus on the nutrient requirements and capacity of growing crops and fail to address the pathogens contained in manure and the fate of those pathogens in the environment. OMAFRA has acknowledged in evidence before the Inquiry that many of the variables relevant to the ability of the subsurface soils at a particular site and within an entire watershed to absorb manure are not considered as a part of nutrient management planning. Similarly, present voluntary best management practices, if followed, provide no assurance of protection of water resources because they do not require consideration of site-specific hydrogeological conditions prior to the release of manure into the environment. In announcing the new Nutrient Management Act, 2001, the Province has proposed by regulation to simply make mandatory nutrient management planning, agricultural best management practices and environmental farm plans. Alert-Sierra argues that such a limited regulatory approach may be no more successful than the present regulatory regime in preventing contamination of drinking water supplies.
Alert-Sierra’s position is that responsible management of Ontario’s surface and groundwater resources requires that the contamination risks of specific development be assessed, taking into consideration the vulnerability of resources in the area of the proposed development and the nature of the development proposed. This risk-based approach to water resource management should include regional aquifer vulnerability mapping and site-specific hydrogeological investigation before permitting development of new agricultural facilities for manure storage or the spreading of manure. The risk assessment should take into consideration factors affecting the absorption capacity of the on-site soils and watershed as a whole in the area of spreading. These factors may include climatic and soil conditions; manure composition; time and rate of spreading; the geology and hydrogeology of the site, plus vulnerability of the local aquifer to contamination; proximity of the site to wellhead recharge areas; and, existing aquifer and surface water quality.
Implementation of this risk-based approach to water resource management will necessitate a comprehensive aquifer mapping and vulnerability assessment program with continuing monitoring. Well-head recharge areas must also be defined. It is Alert-Sierra’s position that only with such a comprehensive regulatory regime in place can current and future groundwater impacts of manure storage and spreading be evaluated. In areas where aquifers are considered to be vulnerable to contamination, such regulation will require site assessment with the risks of agricultural development to be controlled through restricted approvals of specific manure management practices.