In this section
Silver Springs aerial view
Silver Springs Mammoth Vent and pool
photo by H. Means, FGS
Silver Springs Mammoth Vent close-up
Silver Springs is a first-magnitude spring that forms the headwaters of the Silver River. The Silver River and its springs are in the Silver Springs State Park. The park is possibly most famous for its glass-bottom boat rides from which the numerous springs and the associated aquatic life may be viewed. Canoeing, kayaking, and wildlife viewing are popular along the river.
Silver Springs is a group of large vents and smaller springs in the bed or in coves at the edges of the Silver River. There are 30 springs in the Silver Springs group. The largest of the spring vents is Mammoth Spring (also called the Main Spring), which has two vents in the main pool. The largest of the vents is located approximately 100 feet east of the glass-bottom boat loading area. The vent is a horizontal, oval-shaped opening about 5 feet high and 135 feet wide beneath a limestone ledge. The depth of water measured over the vent opening is about 30 feet. The second vent is in the northwestern part of the main pool near the boat loading area. The spring pool measures about 300 feet north to south and 200 feet east to west. The water is clear and light blue, with aquatic vegetation and algae across the sandy spring bottom and limestone substrate.
The flow of Silver Springs is supplied through a vast system of fractures and solution channels in the limestone and dolomite of the Floridan aquifer. An underwater cave system has been mapped at Mammoth Spring. Approximately 45% of the Silver Springs flow is from Mammoth Spring, with added flow from smaller springs and boils downstream of the main pool. The Silver River flows eastward through a dense cypress swamp for about 5 miles to the Ocklawaha River.
The numerous smaller springs in or at the edges of the Silver River are within 0.6 mile of Mammoth Spring. Vent openings in the limestone are clearly visible in the river bottom at most of these springs. Clear, bluish water is characteristic of the Silver River and its contributing springs, with aquatic vegetation and algae common. These springs are described below as they occur west to east, or downstream from Mammoth Spring. Most of the spring names are adopted from Odom (1957). Oscar Spring, Mastodon Bone Spring, Alligator Hole Spring, Garden of Eden Spring, No Name Cove Spring, Turtle Meadows Spring, Turtle Nook Spring, Raccoon Island Spring, and Timber Spring were named by St. Johns River Water Management District and Florida Geological Survey.
Jacobs Well Spring
Jacobs Well Spring is located on the south side of the upper Silver River, approximately 500 feet downstream from Mammoth Spring. The spring is in a large depression with a sandy bottom, with water flowing from a vent beneath a limestone ledge. The ledge is at the bottom of the relatively steep western wall of the depression. Theme park personnel also know this spring as Spring of the Stars or Fish Reception Hall.
Catfish Reception Hall Spring
Catfish Reception Hall Spring is located in the western part of a cove on the south side of the Silver River, approximately 50 feet southeast of Jacobs Well. Catfish Reception Hall is in a large, conical depression, with limestone exposed around the vent.
Bridal Chamber Spring is located in the same cove on the south side of the Silver River, approximately 100 feet southeast of Catfish Reception Hall. Water flows from a deep, vertical vent in the bottom of the limestone depression. This spring is also called The Abyss by theme park staff.
Oscar Spring is in a shallow depression on the north side of the center of the river channel, about 140 feet northeast of Jacobs Well. There are three small vents in the depression, which has abundant aquatic grasses.
Ladies Parlor Spring
Ladies Parlor Spring is located in the south side of the cove, approximately 60 feet southeast of Bridal Chamber. Water flows from two vents beneath a ledge on the bottom of the southwest side of a large depression. There is a strong flow moving the sand and shell fragments as water exits the vent. This spring is also called Florida Snowstorm by theme park staff.
Devils Kitchen Spring A
Devils Kitchen Spring A is located approximately 90 feet northeast of Ladies Parlor. Water flows from vents in a linear crack in the limestone at the bottom of a bowl-shaped depression. Devils Kitchen Spring B is located approximately 50 feet northwest of Devils Kitchen Spring A, with strong flow from a deep vent at the bottom of a limestone depression and a second vent near the side of the depression. Devils Kitchen Spring B was reported by theme park staff to be reactivated after the heavy rains from hurricanes in the fall of 2004.
Alligator Hole Spring Cave
Mastodon Bone Spring
Alligator Hole Spring is located in a circular, bowl-shaped depression along the south side of the Silver River, approximately 150 feet northeast of Devils Kitchen A.
Mastodon Bone Spring is located in the north side of the river, opposite from the peninsula on the south side. This spring has a strong flow, moving sand and shell fragments from a linear limestone crack at the bottom of a depression.
Geyser Spring is located in the western side of the next cove on the south side of the Silver River, about 150 feet southeast of Mastodon Bone Spring. There is a small peninsula of land between Alligator Hole and Geyser. Exposed limestone juts from the bottom of the depression, with water flowing from four large vents and other smaller vents. This spring is also called Spring of Life or Sunken Forest by theme park staff.
Blue Grotto Spring
Christmas Tree Spring
Blue Grotto Spring is located about 100 feet southeast of Geyser in the south side of the cove. There is a large limestone ledge and vent, with limestone boulders on the bottom of the depression. Water flow from the vent is strong, circulating sand and shell fragments.
Christmas Tree Spring consists of six vents in a limestone depression located in a cove on the north side of the Silver River channel, about 400 feet northeast of Blue Grotto. There is a large, old cypress log in the pool and the outline of a small boat on the bottom of the depression. This spring is also called Spanish Spring or Cypress Spring by theme park staff.
Garden of Eden Spring is located about 240 feet east of Christmas Tree, within the next cove on the north side of the Silver River. Water flows from a distinct hole and a small vent in the bottom of a small limestone depression. This spring is also called Popcorn Spring by theme park staff. Garden of Eden is in the same cove as the jungle boat docks.
Indian Cave Spring is located within a small cove on the south side of the Silver River channel, about 250 feet southeast of Garden of Eden. Water flows from a cavity beneath a ledge on the south side of a limestone depression. This spring is also called Catfish Convention Hall by theme park staff.
First Fishermans Paradise Spring
Turtle Meadows Spring
First Fishermans Paradise Spring is located approximately 200 feet east of Indian Cave. Water flows from vents beneath large limestone slabs and rocks in three limestone depressions situated in a line along the south part of the river channel.
No Name Cove Spring is a large depression with little flow, located in a small cove along the south side of the Silver River, about 450 feet east of First Fishermans Paradise.
Turtle Meadows Spring has limestone exposures with two vents located approximately 200 feet northeast of No Name Cove, near the middle of the Silver River channel. There is a 55-gallon drum lodged in the depression.
Second Fishermans Paradise Spring
Second Fishermans Paradise Spring is a limestone depression located in the middle of the river channel about 200 feet southeast of Turtle Meadows. Numerous limestone rocks overlie the vent and small holes on the bottom of the large depression.
Catfish Hotel Spring is located approximately 100 feet southeast of Second Fishermans Paradise. Algae-covered limestone slabs and boulders cover the bottom of the depression, with a strong flow from beneath a limestone ledge.
Turtle Nook Spring
Turtle Nook Spring is located on the northwest side of the forested island in the river, approximately 100 feet northeast of Second Fishermans Paradise. Water flows from beneath a limestone ledge in the bottom of the depression.
Raccoon Island Spring is located in Gar Cove northeast of the island. Flow is from at least 3 small vents in the bottom of the depression.
Shipwreck Spring is a vent located at the bow of a sunken boat on the bottom of a large depression near the center of the river, east of the eastern tip of the island.
Catfish Convention Hall Spring is a vent in a small depression located directly upstream from Shipwreck Spring and the sunken boat.
Silver Springs run
Timber Spring has three vents in a small limestone depression with a sandy bottom. There is a piece of 6-inch by 6-inch timber stuck in one of the vents.
Discharge at Silver Springs has been measured by the U.S. Geological Survey (USGS) 444 times since 1906, and discharge has been measured an average of six times per year since 1970. Discharge is measured in the Silver River about 4,000 feet below the head of the springs. Discharge measurements are currently made monthly. In addition, discharge is also interpolated continuously from stage elevation and water levels in a nearby Floridan aquifer well. The difference between the minimum and maximum discharges is 1040 cubic feet per second (cfs) over the period. The maximum discharge of 1290 cfs was measured in September 1960; the minimum discharge of 250 cfs was measured in January 2001. The mean and median discharges for the period of record are 734 and 735 cfs, respectively (Table 1). Between 2005 and 2010, Karst Environmental Services measured the discharge of Mammoth Spring 11 times. The mean and median discharge of Mammoth Spring is 251 cfs and 247 cfs, respectively (see the table below).
Mammoth Spring was sampled by USGS 142 times since 1956, with additional field measurements periodically through 1984. USGS currently samples the Mammoth Spring (Main Spring) four times per year. The district sampled the Mammoth Spring in 2001 and 2005. Summary statistics of the water quality data for selected variables are shown in the table below.
Summary statistics of water quality and discharge at Silver Springs
|Discharge, cfs, Silver Springs||250.00||734.19||734.50||1290.00||444||1906−2010|
|Discharge, cfs, SSG-Mammoth||193.34||251.40||247.38||330.02||11||2005−2010|
|Alkalinity, total, mg/L as CaCO3||140.0||175.1||169.0||214.0||48||1956−2010|
|Calcium, total, mg/L as Ca||71.3||77.9||78.3||82.8||15||2001−2010|
|Chloride, total, mg/L as Cl||5.0||9.6||9.7||17.0||142||1956−2010|
|Fluoride, total, mg/L as F||0.17||0.19||0.19||0.21||10||2001−2009|
|Magnesium, total, mg/L as Mg||8.5||9.3||9.4||10.4||14||2001−2010|
|Nitrate + nitrite, total, mg/L as N||0.39||0.89||0.92||1.20||59||1974−2010|
|Orthophosphate, total, mg/L as P||0.02||0.04||0.04||0.07||56||1967−2005|
|Phosphorus, total, mg/L as P||0.01||0.04||0.04||0.07||78||1969−2010|
|Potassium, total, mg/L as K||0.5||0.6||0.6||0.9||11||2006−2010|
|Sodium, total, mg/L as Na||5.8||6.7||6.7||7.4||14||2001−2010|
|Specific conductance, field, µmhos/cm at 25°C||438||463||462||486||34||2000−2010|
|Specific conductance, lab, µmhos/cm at 25°C||350||428||423||492||165||1956−2010|
|Sulfate, total, mg/L as SO4||18.0||37.5||38.0||58.0||83||1956−2010|
|Total dissolved solids, mg/L||229||268||270||318||79||1960−2010|
|Water temperature, °C||21.0||23.1||23.0||27.5||167||1960−2010|
mg/L = milligrams per liter
cfs = cubic feet per second
Age of discharge water
One of Silver Springs Many Vents
The age of water discharging from Mammoth Spring was determined by measuring the concentration of tritium, delta carbon-13, and carbon-14 from discharge, which was measured in May 2001. Mammoth Spring had a tritium concentration of 3.51 tritium units, which suggests that the water is less than 48 years old. USGS measured tritium and helium-3 in Mammoth Spring, Catfish Reception Hall, and Blue Grotto in January 2002 and found the tritium/helium-3 ages to be 27, 10, and 19 years, respectively (Phelps, 2004). Mammoth Spring had a delta carbon-13 value of −10.0 parts per thousand and a carbon-14 concentration of 47% modern carbon, which results from the reaction of rainfall with calcite, dolomite, and sediment organic matter. The adjusted carbon-14 age is recent.