Fla. Stat. § 7.57
The boundary lines of Seminole County are as follows: Beginning in the center of Wekiva River and in the center of the St. Johns River, at the place where the Wekiva River discharges its waters into the St. Johns River; thence through the thread of the said Wekiva River in a southerly direction to the northwest corner of section thirty-one, township twenty south, of range twenty-nine east; thence south on the range line between ranges twenty-eight and twenty-nine east, to the southwest corner of section nineteen, township twenty-one south of range twenty-nine east; thence east to the southeast corner of section twenty, township twenty-one south of range thirty east; thence south to the township line between townships twenty-one and twenty-two south of range thirty east; thence east on said township line to the thread of the St. Johns River; thence following the thread of the St. Johns River to and through Lake Harney, into the St. Johns River; thence following the thread of the St. Johns River to and through Lake Monroe, into the St. Johns River; thence following the thread of the St. Johns River to its juncture with the Wekiva River at the point of beginning.
The common boundary line between the counties of Seminole and Volusia, from the place where the St. Johns River enters Lake Harney to the corner common to Volusia, Seminole, Orange and Brevard Counties is more fully defined, located and described as beginning where the center line of the St. Johns River enters Lake Harney at a point approximately seven hundred feet west of the south half mile post of section twenty, township twenty south, range thirty-three east, thence southeasterly following the center line of the St. Johns River to Puzzle Lake at a point one thousand feet south and three hundred feet west of the east half mile post of section four, township twenty-one south, range thirty-three east, thence southwesterly to a point in Puzzle Lake six hundred sixty feet north of the southwest corner of the southeast quarter of the southeast quarter of said section four, thence south one and one eighth miles through Puzzle Lake to the south line of section nine, thence southeasterly to the point where the center line of the St. Johns River enters Puzzle Lake in the southwest quarter of section fifteen, township twenty-one south, range thirty-three east, thence southeasterly along the center line of the St. Johns River and the easterly channel thereof to a point in the southeast quarter of section twenty-seven, township twenty-one south, range thirty-three east, where the two channels unite, thence following the center line of the St. Johns River southeasterly to a point approximately four hundred feet east of the south half mile post of section thirty-five, township twenty-one south, range thirty-three east. Said point being corner common to Volusia, Seminole, Orange and Brevard Counties.
Fla. Stat. § 7.57