A little while back Dan Farber at Legal Planet posted "Ronald Reagan – Environmentalist Governor". Some excerpts:
It may surprise you to learn this — it certainly surprised me. But Ronald Reagan has been called “the most environmental governor in California history — protecting wild rivers from dams, preserving a Sierra wilderness by blocking highway builders, creating an air resources board that led to the nation’s first auto smog controls.” This may be an exaggeration, but there were some major environmental achievements.
[An LA Times story] recounts Reagan’s support for legislation to create the Lake Tahoe interstate compact in order to save the lake.... In addition... Reagan was instrumental in securing legal protection for California’s wild and scenic rivers.
Perhaps most notably, Reagan signed the California Environmental Quality Act. He also signed the signed the Mulford-Carrell Act, combining the Bureau of Air Sanitation and the Motor Vehicle Pollution Control Board to create the California Air Resources Board (CARB). Reagan appointed the first head of the Board, Arie Jan Haagen-Smit, a Cal Tech chemist who was responsible for linking smog to automobile emissions. By all account, this “stubborn Dutchman” was a dedicated and successful champion of pollution control.
Reagan as President was a much different figure. As we all know, his Administration was no friend to the environment. But even during his Presidency, there were some bright spots, such as his enthusiastic signing of the Montreal Protocol to protect the ozone layer.
In short, Reagan was a more complicated figure than the stereotyped right-winger that both ends of the political spectrum have portrayed. And in his California days, he had a legitimate claim to be considered an environmentalist.