A national conservation group has reached an agreement to buy nearly 20,000 acres of timberland in northwestern Sonoma County, a move that derails the long-disputed, forest-to-vineyards conversion project pushed by CalPERS, the giant state workers pension fund.

CalSTRS, the state pension fund for public school teachers, has a major investment in a private-equity firm that in turn owns a company that owns Bushmaster Firearms International, which manufactured the rifle used in the mass shooting in Newtown, Conn.

California’s pension system lowered a key estimate of future investment returns Wednesday, a move that will drive up pension costs for cities across Sonoma County and further squeeze public services. The decision will mean yet another hit to beleaguered local budgets as CalPERS jacks up pension contributions by public agencies to make up for lower investment returns.

The full CalPERS board voted this morning to lower its forecast from 7.75 percent to 7.5 percent. The change is expected to cost the state an additional $167 million a year out of the general fund. CalPERS’ chief actuary had recommended a reduction to 7.25 percent.

CalPERS has ended months of uncertainty by signaling to Sonoma County that it intends to move forward with a huge, controversial timber-to-vineyard conversion project near Annapolis.

So did Sonoma County meet its earnings goal its first year after issuing $289 million in pension obligation bonds? It wasn’t even close. According to records recently posted by SCERA, the association achieved a return for 2011 of 1 percent, missing its mark by 6.75 percent.

Healdsburg city officials learned Tuesday that they face a $26 million gap for funding public employee retirements, a situation described as “bleak” and “grim” by City Council members. In what Mayor Gary Plass said was a painful, but necessary exercise, the council heard the analysis by Joe Nation, a Stanford professor and former North Bay assemblyman, whom they invited to scrutinize city’s pension plans.

If you write about public employee pension programs, it’s not unusual to be accused of “pension envy.”

The state pension fund is parting ways with Premier Pacific Vineyards, a Napa firm that manages its portfolio of vineyard properties. Sources say the move threatens Preservation Ranch, the controversial 1,769-acre forest-to-vineyard conversion project in northwestern Sonoma County.

Rank-and-file state employees aren’t allowed to simultaneously collect wages and pensions. There’s an exemption for political appointees, but double-dipping isn’t limited to political appointees.