Using Critical Loads to Protect Canadian Ecosystems from Damage due to Acid Deposition Kerri Timoffee* Environment Canada Transboundary Air Issues Branch, Ottawa (* plus a many others, e.g., Silvina Carou, Dean Jeffries, Mike Moran, C.-H. Ro, R.J. Vet) WESTAR Council Understanding the Critical Loads Approach Denver, November 15-16, 2005

Outline Post-2000 Acid Rain Strategy How we got there Scientific evidence of impacts, basis for 1982 deposition targets & decision process control programs and anticipated ecological benefits Current status 2004 Canadian Acid Deposition Science Assessment Current situation with respect to critical loads Next Steps Forecasting the future Where to next

Canada’s current policy instrument is the 1998 Canada-Wide Acid Rain Strategy for Post-2000 Signed by all Federal/Provincial/Territorial Energy and Environment Ministers Main elements Reduce acidifying emissions in eastern Canada and the United States Prevent pollution and keep clean areas clean Maintain an adequate science and monitoring program Report annually Long term goal is to reduce acid deposition to below critical loads across Canada

Early scientific evidence for ecological impacts in Canada acidic lakes, damage to terrestrial vegetation near smelters, Gorham and Gordon, 1960 acidification damage in cottage country far from local emission sources, Dillon et al, 1977 decrease in number and variety of fish species in lakes and rivers of Ontario and the Atlantic provinces, BRCG, 1979

Canada realised that controlling acid deposition would require an effects-based program Large but local sources Worlds’ tallest “superstack” was built Air quality standard addresses local air pollution problem missed the problem of damage downwind & cumulative exposures

Sulphate loadings and observed effects as basis for defining deposition targets AreaLoading ( Kg/Ha*Yr) Observations I.L.W.A.S. Project, Adirondacks 40 Acidified lakes in the area Southern Norway20-40 Acid lakes, fish populations lost Hubbard Brook, New Hampshire 35 Acid lakes in the area Muskoka-Haliburton, Ontario 30 pH depression, evidence of biological damage Algoma20 Acidic headwater lakes Nova Scotia20 Acidified Rivers Minnesota Boundary Waters 14 Some pH depression, no biological effects reported ELA, Northeastern Ontario 10 No apparent detrimental effects observed in 10 yrs of study

Canada adopted a critical load to protect aquatic ecosystems in 1982 aquatic evidence was sufficient forest damage was, and still is, controversial experimental cause-effect evidence of the chemical processes and sequence of biological changes as acidification progressed targeted wet sulphate deposition In 1982, Canada proposed a critical load of 20 kg/ha/yr to protect all but the most sensitive areas In 1983 New England Governors and Eastern Canadian Premiers endorsed the 20kg/ha/yr target.

Projected impact of reducing SO 2 emissions on the amount of wet sulphate deposited annually Wet sulphate deposition (approx. kg/ha/yr) Estimated effects of reducing SO2 emissions by AreaNow 50% in Canada 100% in Canada 50% in Canada 50% in US Muskoka’s Quebec City Central Nova Scotia Adirondacks Vermont/New Hampshire

Emission Reduction Control Programs 1984 Sulphur Protocol 30% reduction in SO 2 emissions national cap of 3.2 million tonnes beginning in 1993 no particular environmental limit 1985 Eastern Canada Acid Rain Program plan to reduce total national emissions by 30% over the next ten years, about 50% of the emissions in Eastern Canada Goal to protect moderately sensitive aquatic ecosystems Committed to further science 1991 Canada-US Air Quality Agreement reiterated the national cap

Reporting indicated that both countries would meet their targets for emission reductions, so the expectation was for ecosystems to improve Expectation that aquatic and terrestrial ecosystems would recover significantly Perhaps restore the most sensitive aquatic ecosystems

Canada developed new critical loads to fully protect all surface waters Critical load values (kg/ha/yr) of sulphate in precipitation <=8 8 < <=12 <=1610 < 16 <<=20 20 <

Even with full implementation of Canadian and US programs, almost 800,000 km 2 in southeastern Canada would still receive harmful levels of acid deposition Area of eastern Canada expected to receive wet SO4 deposition above critical loads (in kilograms per hectare per year) in 2010, without further controls beyond provisions in the 1991 Canada-US Air Quality Agreement

These critical loads and exceedance estimates were accepted by the scientific and political communities as the basis for developing the Post-2000 Acid Rain Strategy Strategies goal is to achieve sulphate deposition levels that do not exceed “critical loads” Scenario modelling predicted the changes in critical load exceedances resulting from further reductions in SO2 emissions in eastern Canada as well as the US 25% cut in SO 2 emissions → 34% reduction in area receiving harmful levels 50% cut in SO 2 emissions → 72% reduction 75% cut → virtually all of eastern Canada would be protected from acid deposition

Current Status - Time Series CAPMoN and CASTNet Networks

Current status - Changes in nssSO 4 = Wet Deposition Patterns Mean nssSO 4 = Wet Deposition (Kg/Ha/Yr) Mean nssSO4= Wet Deposition (Kg/Ha/Yr)

Aquatic CLs 5 th percentile value for all lakes located within a grid square Index map shows which model produced the grid value 1983 target load (20 kg/ha/yr) covered by lowest four classes 21% of eastern grid squares in lowest CL category

Area of Eastern Canada at Risk from Acid Deposition 0.5 million km million km 2 New science considers both sulphate and nitrate deposition and aquatic and terrestrial ecosystems.

Aquatic “N-leaching” Exceedances 95 th exceedance value for all lakes within a grid square Current situation (note both positive and negative exceedance classes) Largest (orange) exceedances occur in southern NS/NB and ON Positive exceedance even occur in NW ON (but none in west)

Forecasting the Future Annual Effective Acidity Wet Deposition (combined annual SO 4 and NO 3 wet deposition) “First generation” Can-US SO 2 and NO X emissions reductions Most realistic Can-US SO 2 and NO X emissions reductions Implementation of current (e.g. Post-2000 Strategy) and proposed (e.g. U.S. Clear Skies) legislation is predicted to reduce the effective acidity of wet deposition by at least 30% over much of eastern North America by keq/ha/yr

Forecasting the Future Implementation of current (e.g. Post-2000 Strategy) and proposed (e.g. U.S. Clear Skies) legislation, will reduce but not eliminate acid damage in eastern Canada. Aquatic Terrestrial It is estimated that a further reduction in SO 2 of ~75% will be required from Canada and the U.S. beyond those agreed to in the Canada- U.S. Air Quality Agreement to end acid rain. Draft

Where to Next New critical loads and preliminary exceedance estimates Adjust our control control actions Further domestic cuts Decrease TB flows Increase effort at KCAC/PP Monitor and report on ecological benefits

Summary Concept of working towards reducing deposition to below critical loads has long been central to Canada’s SO 2 management program There are still many regions of eastern Canada (and perhaps even small parts of western Canada) where present-day deposition levels exceed aquatic critical loads Developing critical loads is an iterative process

Challenges Concern that any sulphur dioxide control program would require large, and possibly expensive, reductions

Region of Concern: Where Ecosystem Effects Likely Occur Region of Concern: Where Ecosystem Effects Likely Occur (contains ~ water bodies) Environment Canada (1988)

Contact information Kerri Timoffee Manager, Acid Rain Program Transboundary Air Issues Branch Environment Canada Rm 1118, 351 St Joseph Blvd Gatineau, Quebec K1A 0H3 Telephone: (819) Fax: (819)