FLORIDA GEOLOGICAL SURVEY


 LEON COUNTY

St. Marks River Rise


 Figure 51. St. Marks River Rise (photo by H. Means).
Location Lat. 300 16' 33.8" N, Long. 84 08' 56.2" W (NE 1 SW 1 SE 1 sec. 29, T. 2 S, R.
2 E). St. Marks River Rise is located 0.6 miles (0.9 km) south of Natural Bridge Battlefield
Park. The River Rise is on private property but can be accessed by small boat. From the
intersection of SR 267, drive east on US 98 to the public boat ramp sign on the east side of
the St. Marks River. St. Marks River Rise is 6.5 miles (10.5 km) upstream from the boat
ramp.

Description St. Marks River Rise issues from an elongated fracture in the limestone. The
river rise pool diameter measures 315 ft (96 m) east to west and 195 ft (59 m) northwest to
southeast. Just south of the vent, the St. Marks River widens to 420 ft (128 m) northwest
to southeast. The vent is nearly circular and its diameter is approximately 90 ft (27 m).
River Rise pool depth measures 62 ft (15.7 m). The vent is limestone with almost a sheer
drop on northeast side from 18 ft (5.5 m) to 48 ft (15 m). Area near the vent is choked with
Hydrilla, and there is abundant native aquatic grass farther downstream. Some water
hyacinth is present. Uplands near the spring rise gently to approximately 5 ft (1.7 m) above
water level and are generally forested with a mix of pines, oaks, and cabbage palms.

Utilization Land around the river rise is privately owned and access is restricted to dirt
4 x 4 tracks. A pipe leads into the vent from the north.

Discharge December 18, 2001: 452 ft3/s.