A California town’s plan to declare itself a mountain lion sanctuary as a way to avoid having to build affordable housing is against the law, the state attorney general said Sunday.

The wealthy Silicon Valley enclave of Woodside announced in a memorandum last week that it was exempt from a new state housing law that allows for duplex development on single-family lots because the entire town is habitat for endangered cougars.

Woodside’s declaration is a “deliberate and transparent attempt” to avoid complying with Senate Bill 9, which was enacted last year, Attorney General Rob Bonta said in a letter to officials in the town of 5,500 residents. SB 9 seeks to increase housing availability by allowing denser development.

“This memorandum is — quite clearly — contrary to the law, and ironically, contrary to the best interests of the mountain lions the town claims to want to protect,” Bonta wrote. “My message to Woodside is simple: Act in good faith, follow the law, and do your part to increase the housing supply. If you don’t, my office won’t stand idly by.”

Town officials didn’t immediately respond Sunday to a request for comment on Bonta’s letter.

Any exemption under SB 9 requires the town to examine the attributes of an individual parcel of land, the attorney general’s office said in a news release.

“An entire town cannot be declared habitat for a protected species, and the exemption of a specific lot would have to be based on substantial evidence,” the statement said.