Climate change is worsening flooding but it will also bring faster spring runoffs, hotter summers, more evaporation and droughts. What will that mean for Ontario's drinking water supply? Source water protection committees are trying to plan ahead.
According to the Minister of Environment and Climate Change Glen Murray's Annual Report on Drinking Water 2014:
Under the Clean Water Act, climate change is being considered as we take action to protect sources of drinking water. Source protection committees are using water budget models to determine whether a municipality will be able to meet existing or planned future water demand for average and drought climate conditions.
Where there are potential water quantity issues, committees have identified measures that can be used to ensure sustainable drinking water sources.
The Environmental Commissioner of Ontario (ECO), explained in 2008 that "by mid-century much of southern Ontario will receive 10 to 20 per cent less precipitation and will experience considerable warming (of two degrees Celsius or more) during the warm season. These changes indicate that the risk of summer droughts will increase over the coming years."
In addition to the challenges facing the agriculture, forestry and fisheries sectors, municipal drinking water will also be affected.
Initiatives that are already underway to prepare for lower water levels include:
Water budgets under s. 15(1) of the Clean Water Act, 2006.
As explained by the Trent Conservation Coalition Source Protection Committee, one of the Committees preparing the water budgets mentioned by Minister Murray:
A water budget is an accounting of the inputs and outputs of water in a hydrologic system. It quantifies the components of the hydrologic cycle and the human uses of water employing the available data and a water balance equation based on the law of conservation of mass. The results provide insight into how water moves in the watershed and are useful for the management of water quantity. A water quantity stress assessment examines percent groundwater and surface water demand against thresholds to determine if water systems are stressed.
The ECO anticipates that these water budgets "will be a valuable tool to help inform PTTW [Permit To Take Water] decision-making and ensure that water is managed through the program in a long-term sustainable manner."
Monitoring water quantities taken under PTTW
One of the mandatory requirements of a PTTW is an obligation to collect and record the volumes of water taken daily and submit records each year to the Ministry's online Water Taking and Reporting System (WTRS). The ECO has recommended that the Ministry use this information to phase in reductions to allow for low flow conditions, consistent with the Ontario Low Water Response Strategy.
The Ontario Low Water Response Strategy
As described by the Ministry of Agriculture Food and Rural Affairs [emphasis added]:
Ontario Low Water Response (OLWR) is a strategy for local water users and those with an interest in water use to have input into the environmental, economic and social well being of their community. Water Response Teams are established in areas experiencing low water conditions so the local community can carry out actions to reduce and better manage water use. OLWR is intended to ensure that the province is prepared in case of low water conditions. The province provides overall direction while creating a partnership between provincial and local authorities to form a response to drought events.
In order to recognize and measure the severity of a low water condition, precipitation, stream flow and water levels are monitored regularly by conservation authorities and the Ministry of Natural Resources. Conditions are described as one of three increasingly severe levels of low water (see chart below). Water Response Teams will decide on an appropriate response that may include the actions suggested in the chart below. Other measures and conservation practices may be initiated.
- Condition – The potential for water supply problems is identified.
- Action – Water users will be asked to voluntarily reduce their water consumption by 10%
- Condition – Minor water supply issues are encountered. There is the potential for major supply problems.
- Action – Water users will be asked to voluntarily reduce their water use by 20% or greater.
- Condition – Supply no longer meets demand. Social and economic impacts are experienced.
- Action – Voluntary measures have not produced the necessary response. Restrictions proposed by the Water Response Team and approved by the Government of Ontario will be put into action.
As of September 2012, when the ECO last addressed this issue: "Although the physical criteria for a Level III declaration have been met at various times since the Plan was adopted, the Low Water Committee has never declared a Level III condition." The ECO recommended a full policy review of the Ontario Low Water Response Plan, citing significant concerns with the effectiveness of the program including prohibitive hurdles to obtaining a Level III declaration. We are not aware of any planned review, but given the Minister's apparent commitment to climate change, perhaps such a review is under consideration or will be should drought conditions worsen as predicted.
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