In this section
Mud Spring main view
Mud Spring boil
Mud Spring is a fourth-magnitude spring with an oval-shaped pool about 85 feet long and 65 feet wide. The spring flows from a vertical vent in the center of the pool, producing a prominent boil on the surface. The spring forms the head of Mud Creek, with the discharge flowing down a meandering run toward the southwest for about 1 mile to Little Lake George. The spring is situated along a hiking trail and is a popular picnic area in the state forest.
Mud Spring boil close-up
Discharge at Mud Spring was measured by St. Johns River Water Management District 12 times from 1995 to 2001. The difference between the minimum and maximum discharges is 2.73 cubic feet per second (cfs) over the period. The maximum measured discharge of 3.16 cfs occurred in May 1978; the minimum discharge of 0.43 cfs occurred in May 1999. The mean and median discharges for the period are 1.16 cfs and 0.75 cfs, respectively (see the table below).
Mud Spring was sampled 15 times by the district from 1995 to 2001. Summary statistics of the water quality data for selected variables are shown in the table below.
Summary statistics of water quality and discharge at Mud Spring
|Alkalinity, total, mg/L as CaCO3||80.0||83.6||83.0||88.0||13||1995−2001|
|Calcium, total, mg/L as Ca||35.8||39.1||38.5||46.0||14||1995−2001|
|Chloride, total, mg/L as Cl||223.6||249.5||251.5||296.0||13||1995−2001|
|Fluoride, total, mg/L as F||0.14||0.15||0.15||0.17||14||1995−2001|
|Magnesium, total, mg/L as Mg||15.6||17.9||17.8||19.7||14||1995−2001|
|Nitrate + nitrite, total, mg/L as N||0.01||0.02||0.02||0.03||10||1996−2001|
|Orthophosphate, total, mg/L as P||0.06||0.08||0.08||0.11||14||1995−2001|
|Phosphorus, total, mg/L as P||0.08||0.08||0.08||0.08||1||2001|
|Potassium, total, mg/L as K||3.8||4.4||4.2||5.4||14||1995−2001|
|Sodium, total, mg/L as Na||115.3||134.5||132.7||170.0||14||1995−2001|
|Specific conductance, field, µmhos/cm at 25°C||943||1056||1036||1272||14||1995−2001|
|Specific conductance, lab, µmhos/cm at 25°C||1010||1129||1117||1272||4||1995−2001|
|Sulfate, total, mg/L as SO4||33.5||39.0||39.2||43.0||14||1995−2001|
|Total dissolved solids, mg/L||489||570||567||667||12||1995−2001|
|Water temperature, °C||22.4||22.8||22.8||23.2||15||1995−2001|
mg/L = milligrams per liter
cfs = cubic feet per second
Age of discharge water
The age of water discharging from Mud Spring was determined by measuring the concentration of tritium, delta carbon-13, and carbon-14 in the spring discharge, which was measured in May 2001. Mud Spring had a tritium concentration of 2.69 tritium units, which suggests that the water is less than 48 years old. Mud Spring had a delta carbon-13 value of −8.98 parts per thousand and a carbon-14 concentration of 34% modern carbon, which results from the mixing of Upper and Lower Floridan aquifer water. The Fontes and Garnier (1979) carbon-14 age is 423 years old.