It's a little longer than 10 years. CESI dates back to an initiative of the national round table in about 2004. The indicators have been updated continuously since then and expanded, and are now reported under the Federal Sustainable Development Act.
But I would emphasize that Environment Canada has had the obligation to report on the state of the environment and to generate indicators at a national, regional, and local level since 1988. Prior to 1988, of course, we go back to the beginning of the Meteorological Service, which is certainly the oldest organization in Environment Canada and has been generating and publishing data for almost a century now.