Wis. Stat. § 66.1024

Whenever an executed and recorded deed, land contract, or mortgage of lands abutting on an existing public street, highway, or alley or a projected extension thereof contains language reserving or excepting certain lands for street, highway, or alley purposes, the reservation or exception shall constitute a dedication for such purpose to the public body having jurisdiction over the highway, street, alley, or projected extension thereof, unless the language of the reservation or exception plainly indicates an intent to create a private way. Any reservation or exception shall not be effective until it is accepted by a resolution of the governing body having jurisdiction over such street, highway, alley, or projected extension thereof.