Some Sacramento-area water agencies would end up paying for a small share of the Delta tunnels under a last-minute alternative funding plan pitched by one of the state’s largest farming groups. Westlands Water District, whose board of directors is scheduled to vote Tuesday on whether to help pay for the tunnels, says it needs to spread the costs among a greater number of water districts, both north and south of the Delta, to make the project affordable to the Fresno and Kings county farmers who get water from Westlands.