Water bodies, watersheds and storm water
Boulder Spring main view
Boulder Spring
Location
Boulder Spring is located in the Seminole State Forest about 1.6 miles southeast of Cassia. From the south entrance of Seminole State Forest on State Road 46 (about 0.4 mile west of the Wekiva River), turn north and drive past the stop sign, through the gate, and cross the bridge over Black Water Creek. Drive about 0.2 mile past the bridge to the next intersection. Turn right at the intersection, and go 1.2 miles to the intersection of two horse trails and Palatka Road. Walk toward the left onto the northernmost horse trail (vehicles are not permitted on the horse trails), and go 0.5 to 0.6 mile to the clearing on right side of trail. Walk about 200 feet toward the northeast to Boulder Springs. Access and fee information can be obtained at the Seminole State Forest south entrance.
Latitude 28°52’17.97” N, Longitude 81°27’00.36” W
NW¼ NW¼ NE¼ sec. 6, T 19 S, R 29 E
Boulder Spring pool
Description
Boulder Spring is a fifth-magnitude spring. The spring head is a small pool in an area of limerock outcrop, with large limestone boulders in the spring pool and run. Water flows from vents at the base of the hillside and in sand boils in the spring run as it flows about 0.3 mile toward the northwest to Sulphur Run.
Discharge
Boulder Spring run
Discharge at Boulder Spring was measured by St. Johns River Water Management District (SJRWMD) in 2003, 2005, and 2008. The mean and median discharge was 0.23 and 0.32 cubic feet per second.
Water quality
Boulder Spring was sampled once in 2004 by Lake County and once in 2005 by SJRWMD. Summary statistics of the water quality data for selected variables are shown in the table below.
Summary statistics of water quality and discharge at Boulder Spring
| Boulder Spring | Min | Mean | Median | Max | Count | Period |
|---|---|---|---|---|---|---|
| Discharge, cfs | 0.06 | 0.23 | 0.32 | 0.32 | 3 | 2003–2008 |
| Alkalinity, total, mg/L as CaCO3 | 120.0 | 120.5 | 120.5 | 121.0 | 2 | 2004–2005 |
| Calcium, total, mg/L as Ca | 98.8 | 98.8 | 98.8 | 98.8 | 1 | 2005 |
| Chloride, total, mg/L as Cl | 110.0 | 114.5 | 114.5 | 119.0 | 2 | 2004–2005 |
| Dissolved Oxygen | 5.80 | 5.80 | 5.80 | 5.80 | 1 | 2004 |
| Magnesium, total, mg/L as Mg | 25.4 | 25.7 | 25.7 | 26.0 | 2 | 2004–2005 |
| Nitrate + nitrite, total, mg/L as N | 0.07 | 0.08 | 0.08 | 0.10 | 2 | 2004–2005 |
| Orthophosphate, total, mg/L as P | 0.06 | 0.06 | 0.06 | 0.06 | 1 | 2005 |
| pH, field | 7.20 | 7.39 | 7.39 | 7.57 | 2 | 2004–2005 |
| Phosphorus, total, mg/L as P | 0.18 | 0.18 | 0.18 | 0.18 | 1 | 2005 |
| Potassium, total, mg/L as K | 2.4 | 2.7 | 2.7 | 2.9 | 2 | 2004–2005 |
| Sodium, total, mg/L as Na | 63.3 | 64.5 | 64.5 | 65.7 | 2 | 2004–2005 |
| Specific conductance, field, µmhos/cm at 25°C | 989 | 1015 | 1015 | 1041 | 2 | 2004–2005 |
| Specific conductance, lab, µmhos/cm at 25°C | 1041 | 1041 | 1041 | 1041 | 1 | 2005 |
| Sulfate, total, mg/L as SO4 | 216.0 | 216.2 | 216.2 | 216.4 | 2 | 2004–2005 |
| Total dissolved solids, mg/L | 619 | 675 | 675 | 730 | 2 | 2004–2005 |
| Water temperature, °C | 22.7 | 22.9 | 22.9 | 23.0 | 2 | 2004–2005 |
mg/L = milligrams per liter
cfs = cubic feet per second
Age of discharge water
The age of water discharging from Boulder Springs was determined by measuring the concentration of tritium, carbon-14, and carbon-13 in the spring discharge, which was measured in March 2005. Boulder Springs had a tritium concentration of 0.51 tritium units, a carbon-14 concentration of 29 percent modern carbon, and a delta carbon-13 value of –9.78 parts per thousand. The tritium concentration suggests that the water is between 40 and 70 years old. The carbon-14 concentration of 29% modern carbon can result from the reaction of rainfall with calcite, dolomite, and soil organic matter and from the mixing with Lower Floridan water.
