Florida voters appear poised in November to pass a constitutional amendment that would require setting aside billions of dollars for land conservation and other environmental projects.

The proposed Water and Land Conservation amendment would earmark 33 percent of the state’s documentary-stamp tax revenues—fees paid when real estate is sold—for 20 years. The money would go to buy conservation lands, protect areas vital to the water supply and restore natural systems that have been degraded, such as the Everglades.