St. Johns River Water Management District St. Johns River Water Management District St. Johns River Water Management District St. Johns River Water Management District St. Johns River Water Management District St. Johns River Water Management District
St. Johns River Water Management District -

Water bodies, watersheds and storm water
Blue Spring main view

Blue Spring main view
photo by T. Scott, FGS

Blue Spring pool with swimmers

Blue Spring pool with swimmers

Blue Spring run

Blue Spring run

Blue Spring

Volusia County


Blue Spring is a first-magnitude spring with a nearly circular pool about 135 feet long from north to south and 100 feet from east to west. Steep banks 10 feet to 20 feet high surround the pool except to the south, where the spring opens to the spring run. The pool bottom is mostly limestone and sand; the spring vent is an elongated opening in the limestone about 15 feet from the north edge of the pool. From the limestone ledge, the vent slopes precipitously to about 40 feet in depth. A limited underwater cave system has been mapped at Blue Spring. From the pool, the spring run flows 0.2 mile to the south, then to the southwest for another 0.2 mile to the St. Johns River. The run varies from 70 feet to 100 feet in width and is bounded by steep wooded slopes except for the lower southeast bank, where the terrain flattens considerably. Flow of the spring is retarded by backwater during high stages of the St. Johns River.

Blue Spring State Park is owned and operated by the state of Florida, providing a wide range of recreational activities, including swimming, diving, canoeing, fishing, hiking, and camping. Manatees commonly frequent the spring run during the winter months when the spring water is considerably warmer than the St. Johns River.


Blue Spring run to the St. Johns River

Blue Spring run to the St. Johns River

Discharge at Blue Spring was measured by the U.S. Geological Survey (USGS) from 1932 to 2010, and USGS currently performs continuous discharge measurements. St. Johns River Water Management District measured discharge from 1983 to 2001. The difference between the measured minimum and maximum discharges is 131 cubic feet per second (cfs). The maximum measured discharge of 218 cfs occurred in February 1983; the minimum discharge of 87.0 cfs occurred in November 2001. The mean and median discharges for the period from 1932 to 2010 are both 154 cfs (see the table below).

Blue Spring Discharge Graph
Discharge Graph

Water quality

Blue Spring was sampled by USGS from 1960 to 2000. The district sampled Blue Spring from 1984 to 2010 and currently samples the spring four times per year. Summary statistics of the water quality data for selected variables are shown in the table below.

Blue Spring Water Quality Graph
Water Quality Graph

Summary statistics of water quality and discharge at Blue Spring

Blue Spring — Volusia County Min Mean Median Max Count Period
Discharge, cfs 87.00 154.43 154.00 217.73 1418 1932−2010
Alkalinity, total, mg/L as CaCO3 105.0 135.8 138.0 170.0 85 1960−2010
Calcium, total, mg/L as Ca 41.0 66.9 66.8 81.7 58 1992−2010
Chloride, total, mg/L as Cl 110.0 396.6 390.0 700.0 238 1960−2010
Dissolved Oxygen 0.21 0.38 0.35 0.64 19 2006−2010
Fluoride, total, mg/L as F 0.07 0.08 0.09 0.10 19 1996−2009
Magnesium, total, mg/L as Mg 12.8 24.9 24.8 39.1 58 1992−2010
Nitrate + nitrite, total, mg/L as N 0.04 0.47 0.42 1.20 82 1976−2010
Orthophosphate, total, mg/L as P 0.01 0.07 0.07 0.10 58 1972−2010
pH, field 6.50 7.39 7.40 8.20 97 1960−2010
Phosphorus, total, mg/L as P 0.01 0.07 0.07 0.14 74 1972−2010
Potassium, total, mg/L as K 4.1 7.3 7.4 11.3 58 1992−2010
Sodium, total, mg/L as Na 78.8 196.6 196.8 314.0 58 1992−2010
Specific conductance, field, µmhos/cm at 25°C 729 1535 1501 2320 60 1984−2010
Specific conductance, lab, µmhos/cm at 25°C 808 1662 1650 2610 242 1960−2010
Sulfate, total, mg/L as SO4 25.1 56.6 55.0 100.0 99 1960−2010
Total dissolved solids, mg/L 462 828 827 1230 95 1960−2010
Water temperature, °C 21.5 23.2 23.0 25.6 351 1932−2010
Units: µmhos/cm = micromhos per centimeter
         mg/L = milligrams per liter
         cfs = cubic feet per second

Age of discharge water

The age of water discharging from Blue Spring was determined by measuring the concentration of tritium, delta carbon-13, and carbon-14 in the spring discharge, which was measured in May 1996, and the concentration of tritium and helium-3 in the discharge, as measured in February 2001. Blue Spring had a tritium concentration of 3.8 tritium units, which suggests that the water is less than 43 years old. The tritium/helium-3 age was 22 years. Blue Spring had a carbon-14 concentration of 45% modern carbon and a delta carbon-13 value of −10.10 parts per thousand, which results from the mixing of Upper and Lower Floridan aquifer water. The adjusted carbon-14 age is recent.


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St. Johns River Water Management District
4049 Reid Street, Palatka, FL 32177
(800) 725-5922