Internal polls taken by the Santa Clara Valley Water District, Silicon Valley’s largest water provider, show that voters oppose the idea of extending the term limits of the district’s board members. But the district’s board, by a 4-3 vote, decided last month to spend $3.2 million in public funds to place a measure on the June 7 Santa Clara County ballot to do it anyway, using language that critics say misleadingly implies the measure would limit board members’ terms.