The Nature Conservancy said yesterday that it had raised $50 million to conserve land in Maine, the group’s most expensive conservation project yet. Thirty million dollars will buy 185,000 acres along the Upper St. John River, the largest free-flowing river east of the Mississippi, with the remaining millions funding some 35 other conservation projects. The conservancy’s fundraising effort ended two years ahead of schedule, with big donations coming from the president of L.L. Bean, Rockefeller family members, and Tom’s of Maine, among others. Maine Gov. Angus King (I) said the fundraising success showed that citizens do not need to turn to government to solve their problems.