California’s contributions to the California State Teachers’ Retirement System are projected to almost triple in less than a decade and may increase even more due to low investment returns and the cost of benefits enhanced in boom times.

The decision by CalSTRS on Feb. 1 to cut its target return to 7 percent over two years means higher payments from the state, schools and educators to make up the difference. By law, the state’s annual increase in payments is capped at 0.5 percent and officials are assuming that will be the growth rate for many years to come, said H.D. Palmer, a spokesman for the finance department.