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Rideau Canal National Historic Site of Canada

The Rideau Canal Environmental Site Assessment Project for Indian, Newboro and Upper Rideau Lakes

Backgrounder

The Rideau Canal National Historic Site is in the process of completing a multi-year Environmental Site Assessment (ESA) for Indian, Newboro and Upper Rideau Lakes, with the purpose of studying the water and sediments from each of the lakes. The ESA process is funded by a national program that supports federal departments and agencies to assess the environmental health of sites under their responsibility. It is a multi-step process that begins with historical reviews of local industrial, commercial and agricultural activities, followed by a field sampling program, and if necessary a risk assessment study to assess potential risk to human health, wildlife and the environment.

The ESAs for Indian, Newboro and Upper Rideau Lakes were initiated by the Rideau Canal in the fall of 2009, after a Masters student and two undergraduate students from Queen's University found that some lake sediments contained concentrations of metals that were above federal and/or provincial environmental quality guideline values.

The Rideau Canal is currently studying a number of other areas along the length of the canal, including the Kingston Inner Harbour, two terrestrial sites in Smiths Falls, and the sediments of the Rideau River.

Historical Use

The land surrounding the three lakes has had human influence throughout the canal’s history. The local area has been impacted by mills as well as other forms of industry. Transportation via the waterway was historically used to link communities and move raw materials. Similar to other boating destinations, the Rideau Canal has a legacy of many years of recreational boating activities, in which leaded gasoline was used by boaters. In addition, the rich mica deposits in the region promoted the emergence of several mining operations.

Sampling Results To-Date

Rideau Canal ESAs

In 2009, the Rideau Canal hired a consultant to take water and sediment samples throughout each of the three lakes to assess the presence and distribution of substances that could potentially impact human health and the environment. The results from the consultant’s study can be briefly summarized as follows:

  • The ESA water analysis results indicate that the majority of water samples met federal and/or provincial environmental quality guideline values.
  • The ESA sediment results found that some sampling locations had metals and other substances present above the federal and/or provincial environmental quality guideline levels.

Although there were a number of potential human-related sources identified, the ESAs were not able to conclusively link the presence of substances to any one potential source. The results suggest that there may be either multiple localized sources or a large-scale source, such as atmospheric deposition or local geology (the natural presence of substances in local bedrock), at play.

Queen’s University Study

Thanks to the Queen’s University Masters and undergraduate student’s work, Parks Canada has additional information on the three lakes. The students took sediment samples using the same method used in the ESAs (a sediment grabbing device) but went a step further and took sediment cores from the deepest sections of each lake. The analysis of a sediment core can be used to determine the history of lake sediments and can give a more in-depth picture of what has changed over time.

The Queen’s sediment core analysis presented two interesting findings. The highest metal concentrations in the sediment were present between the 1940s and 1970s and are now being buried by an accumulation of new, cleaner sediments, a phenomenon known as “natural capping”. The sediment cores also show that some metal concentrations were at high levels prior to the industrial era, indicating that present levels may be partially explained by local geology or some other natural source.

Next Steps

In order to identify the potential impacts that substances in the lake water and sediment samples may have on the natural environment, the Rideau Canal is using the information from the ESAs and the Queen’s University students’ work as the basis for additional studies. The consultant has been conducting further sampling and analysis over the fall and winter of 2010-11 that involves:

  • Comparing water and sediment analysis results for Indian, Newboro and Upper Rideau Lakes to results from regional reference lakes located off the Rideau Canal system.  This comparison will help to determine if the presence of substances that could potentially impact human health and the environment is an issue that is regional in scale, potentially caused by atmospheric deposition or some other large-scale source.
  • Assessing the diversity and abundance of benthic organisms (small organisms that live in or on the bottom sediments of rivers and lakes). This assessment is important because benthic organisms are one of the primary pathways by which metals and other substances can enter the food chain. They can also give a preliminary indication of risk(s) to wildlife and the natural environment.

Parks Canada is committed to keeping local residents up to date with the progress and results of the ESAs for Newboro, Indian and Upper Rideau Lakes. Local residents who have questions or want to share personal stories of their experiences and knowledge of the historical use of areas around these lakes are encouraged to contact Parks Canada by emailing the Rideau Canal Headquarters at rideaucanal-info@pc.gc.ca.