By Tobias Carroll When you hear about places in the United States that have experienced a crisis in housing, the state of California is often high on the list. Late last year, California’s state government passed a law that would allow duplexes to be built on lots that had previously been zoned for single-family homes. This can be seen as part of a larger movement across the nation — a few years ago, for example, Minneapolis updated its zoning laws to allow more multi-family residences. What happens when zoning laws come into conflict with environmental protection laws? We might well see that …