Apparently Davis Lake, being a Provincial Park, is and always has been off limits. From a thread on BC4x4, there was police at the "entrance" just off the FSR handing out warnings.
Some gov't park plan, April 2002:
http://www.env.gov.bc.ca/bcparks/planning/mgmtplns/davis/davis_lk_draft_mp.pdf
Some gov't park plan, April 2002:
http://www.env.gov.bc.ca/bcparks/planning/mgmtplns/davis/davis_lk_draft_mp.pdf