Water bodies, watersheds and storm water
Welaka Spring main view
Welaka Spring pool
photo by H. Means, FGS
Welaka Spring boil
Welaka Spring
Location
Welaka Spring is located along the St. Johns River on the northern edge of the town of Welaka. From the intersection of State Road (SR) 309 and SR 308B in Welaka, drive north on SR 309 for 1.1 miles, turn west on a sand trail for 0.1 mile, and bear north for 0.1 mile to the spring pool. The spring can also be accessed by boating 1 mile downstream on the St. Johns River from the Welaka public boat ramp.
Latitude 29°29’40.39” N, Longitude 81°40’23.70” W
SW¼ NE¼ SE¼ sec. 33, T 11 S, R 26 E
Description
Welaka Spring is a third-magnitude spring with a pool about 90 feet long from east to west and 60 feet wide from north to south. The spring vent is about 20 feet in diameter in the clayey-sand bottom of the central part of the pool, with a prominent boil over the vent. The water from the spring is clear, but the spring water mixes with dark water from the St. Johns River a short distance downstream. The spring pool opens on its southwest side to a run about 200 feet wide that curves to the southwest, then to the northwest for about 1,200 feet to the St. Johns River. Backwater from the St. Johns River, at least in part associated with tidal effects, frequently makes it impracticable to measure the spring discharge. Welaka Spring is on private property and permission must be obtained prior to visiting the spring.
Discharge
Discharge from Welaka Spring, measured in 2001 by the St. Johns River Water Management District (SJRWMD), was 7.91 cubic feet per second.
Water quality
Welaka Spring was sampled by SJRWMD in 2000 and 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 Welaka Spring
| Welaka Spring | Min | Mean | Median | Max | Count | Period |
|---|---|---|---|---|---|---|
| Discharge, cfs | 7.91 | 7.91 | 7.91 | 7.91 | 1 | 2001 |
| Alkalinity, total, mg/L as CaCO3 | 79.0 | 79.5 | 79.5 | 80.1 | 2 | 2000–2001 |
| Calcium, total, mg/L as Ca | 39.3 | 43.1 | 43.1 | 46.9 | 2 | 2000–2001 |
| Chloride, total, mg/L as Cl | 259.6 | 310.9 | 310.9 | 362.2 | 2 | 2000–2001 |
| Dissolved Oxygen | 0.26 | 0.26 | 0.26 | 0.26 | 1 | 2001 |
| Fluoride, total, mg/L as F | 0.13 | 0.14 | 0.14 | 0.14 | 2 | 2000–2001 |
| Magnesium, total, mg/L as Mg | 18.0 | 21.1 | 21.1 | 24.1 | 2 | 2000–2001 |
| Nitrate + nitrite, total, mg/L as N | 0.01 | 0.02 | 0.02 | 0.03 | 2 | 2000–2001 |
| Orthophosphate, total, mg/L as P | 0.05 | 0.05 | 0.05 | 0.06 | 2 | 2000–2001 |
| pH, field | 7.11 | 7.29 | 7.29 | 7.47 | 2 | 2000–2001 |
| Phosphorus, total, mg/L as P | 0.06 | 0.06 | 0.06 | 0.06 | 1 | 2001 |
| Potassium, total, mg/L as K | 4.5 | 5.3 | 5.3 | 6.1 | 2 | 2000–2001 |
| Sodium, total, mg/L as Na | 141.1 | 172.0 | 172.0 | 202.9 | 2 | 2000–2001 |
| Specific conductance, field, µmhos/cm at 25°C | 1090 | 1192 | 1192 | 1294 | 2 | 2000–2001 |
| Specific conductance, lab, µmhos/cm at 25°C | 1047 | 1047 | 1047 | 1047 | 1 | 2001 |
| Sulfate, total, mg/L as SO4 | 41.2 | 49.5 | 49.5 | 57.7 | 2 | 2000–2001 |
| Total dissolved solids, mg/L | 559 | 676 | 676 | 793 | 2 | 2000–2001 |
| Water temperature, °C | 23.2 | 24.0 | 23.7 | 25.0 | 3 | 1972–2001 |
mg/L = milligrams per liter
cfs = cubic feet per second
Age of discharge water
The age of water discharging from Welaka Spring was determined by measuring the concentration of tritium, delta carbon-13, and carbon-14 in the spring discharge, which was measured in April 2001. Welaka Spring had a tritium concentration of 2.91 tritium units, which suggests that the water is less than 48 years old. Welaka Spring had a delta carbon-13 value of –8.95 parts per thousand and a carbon-14 concentration of 38% modern carbon, which results from the mixing of Upper and Lower Floridan aquifer water. The adjusted carbon-14 age is recent.
