Complex sentence: Appointed Minister for the Environment and Conservation, Cass was unsuccessful in seeking to prevent the flooding of Lake Pedder in Tasmania but did lay the groundwork for the end of sandmining on Fraser Island and government protection of the Great Barrier Reef.
Split into simpler sentences: Appointed Minister for the Environment and Conservation, Cass was unsuccessful in seeking to prevent the flooding of Lake Pedder in Tasmania. Nonetheless he did lay the groundwork for the end of sandmining on Fraser Island and government protection of the Great Barrier Reef.