WASHINGTON — A legal dispute that started with Florida wetlands ended today in a Supreme Court victory for conservatives and private property advocates nationwide. In a 5-4 decision that could impede government regulators at all levels, the court effectively made it harder for public agencies to demand property or money in exchange for issuing a land-use permit. At a certain point, the conservative majority reasoned, these demands amount to an unconstitutional taking of property without compensation. Most immediately, the decision cheers Coy Koontz Jr., a Raleigh, N.C., resident whose late father, Coy Koontz Sr., bought the Florida property in question. Koontz purchased the Orange County land in 1972 with hopes of building a small commercial project. The St. Johns River Water Management District, which covers 18 counties in northeast Florida, subsequently designated much of the property as a “riparian habitat protection zone.” In exchange for securing a permit, Koontz reluctantly agreed to give the district a conservation easement on about 11.5 acres. Citing the loss of valuable wetlands, water district officials told Koontz that he also would have to offer additional mitigation, such as paying to restore about 50 acres of district land elsewhere. He refused, and the district rejected his permit application. So Koontz sued.