In Ontario the federal legislation is key. For the most part the provincial environmental assessment requirements only apply to provincial undertakings. A private proponent, a corporation, for example, that wished to build a bridge or put in a causeway, might not necessarily trigger the provincial environmental assessment process, so the community here relies very heavily on the federal statute.
I know the environmental assessment requirements vary from province to province, so the people of Quebec are quite lucky that they already have that protection in place. But having this national standard ensures that every community across the country enjoys those same opportunities.