U.S. Department of the Interior

U.S. Geological Survey

Fact Sheet 2009-3004

October 2009

Prepared in cooperation with Volusia County

The Water Cycle in Volusia County

Printed on recycled paper

Earth’s surface (fig. 1). This fact 

sheet provides information about 

how much water moves into and 

out of Volusia County, and where 

it is stored. It also illustrates the 

seasonal variation in water 

quantity and movement using 

data from some of the hydrologic 

data collection sites in or near 

Volusia County (fig. 2).

Earth’s water is always in motion. The water cycle, also known as the hydrologic 

cycle, describes the continuous movement of water on, above, and below the 

Basic Concepts

Water that comes from the clouds in 

the form of rain is known as precipitation. 

Water from the clouds falls to the Earth 

and runs downhill into streams and lakes 

as surface runoff. Some of this runoff 

percolates into the soil and deep into the 

ground to be stored in the aquifer. Water 

travels from the aquifer through the 

springs back up to surface streams or to 

the ocean. Water transpires from plants 

and trees and evaporates from the Earth’s 

surface and the ocean, returning to the 

atmosphere. Together these two processes 

are called evapotranspiration, or ET. The 

water vapor from ET condenses to form 

clouds which produce precipitation that 

falls back to the earth. This cycle of the 

never ending movement of water on the 

Earth is called the water cycle.

Most of the water in Volusia County 

is stored in three types of places—the 

atmosphere (where water occurs in 

water vapor and droplets); surface-water 

features such as lakes, wetlands, and 

streams; and in underground reservoirs 

known as the aquifers. The amounts of 

water in these three individual places are 

constantly changing as water moves from 

one place to another. 

Human activity affects the movement of water between the three distinct 

storage places. For example, some people 

use water from lakes, streams, or aquifers for irrigating lawns and crops, or in 

industrial activities such as generation 

of electricity. Irrigation water is used 

by grass and other plants during photosynthesis. Some of the water taken up 

by plants is returned to the atmosphere 

through the process of transpiration. 

Irrigation water that is not used by the 

plants seeps (percolates) into the ground 

as recharge to the aquifers. Residents of 

Volusia County also use water pumped 

from the aquifers for drinking water and 

for household activities such as cleaning, 

bathing, and flushing the toilet. Some of 

this water ends up as wastewater and is 

treated in septic tanks or, more commonly, is discharged into sewers that 

transport the wastewater to wastewater 

treatment plants. Septic-tank drainage 

seeps back into the ground as does treated 

wastewater that is put into percolation 

ponds or sprayed onto the land surface at 

some wastewater treatment plants. However, in most coastal communities and 

near the St. Johns River, treated wastewater is discharged directly into rivers or 

estuaries and flows from the county. 

Figure 1. Major components of the water cycle.

Groundwater and

Surface-water

Outflow

Evapotranspiration

Rainfall

Seepage from

land surface to

groundwater

Groundwater

seepage

and spring

discharge

to land

surface

Where is the water and 

how does it move in Volusia County?
0

1

2

3

J F M A M J J A S O N D

1983-2005

MINIMUM

AVERAGE

MAXIMUM

TOTAL DAILY WATER-VAPOR CONTENT,

IN INCHES

Figure 3. Total daily watervapor content by month, 

1983-2005 (data furnished 

by NOAA, from radiosonde 

station at Kennedy Space 

Center).

Figure 2. Surface drainage features and locations of hydrologic data stations.

95

4

95

Lake George

Lake

Monroe

Lake

Harney

Holly Hill

Daytona

Beach

Deland

New Smyrna

Beach

Lake Apopka

ATLANTIC OCEAN

Sanford

PUTNAM COUNTY

VOLUSIA COUNTY

MARION COUNTY

LAKE COUNTY

SEMINOLE

COUNTY

ORANGE

COUNTY

FLAGLER COUNTY

VOLUSIA COUNTY

BREVARD COUNTY

De Leon

Springs

Crescent

City

Blue

Springs

St.

John’s

River

De Leon

Springs

Tomoka

River

Indian River

L t it le Haw

Creek

Middle Haw Creek

Deep

Creek

Kennedy

Space

Center

Halifax

River

Creek

Deep

Cow Creek

Spruce e Cre k

Lyonia

Preserve

Tiger

Bay

Canal

Gulf

of

Mexico

Atlantic Ocean

81°30’ 81°00’

29°30’

29°00’

28°30’



 0 5 10 MILES

0 5 10 KILOMETERS



EXPLANATION

MAJOR DRAINAGE DIVIDE

SPRING

RAIN GAGE

EVAPOTRANSPIRATION STATION

STREAM GAGING STATION

Volusia

County

FLORIDA

Water does not only move from 

one storage place to another. It is also in 

motion as streamflow on the land surface 

and as groundwater flow through the 

aquifers beneath the land surface. This 

motion is driven by gravity, as the natural 

behavior of water is to “flow downhill”; 

that is, from locations with higher water 

levels to those with lower water levels. 

Most streams in Volusia County begin 

within the county and flow into the 

coastal estuaries, the St. Johns River, 

or Flagler County (fig. 2). Likewise, 

the flow of groundwater is mostly from 

Volusia County to the areas with lower 

water levels, such as the St. Johns River, 

the coastal estuaries, the Atlantic Ocean, 

and parts of surrounding counties. Little 

groundwater flows into Volusia County. 

Thus, most of the water in Volusia 

County, both surface water and groundwater, is of “local” origin, as it ultimately 

results from the rain that falls directly on 

the county. 

Of course the St. Johns River, on the 

western edge of Volusia County, drains 

parts of Volusia County and also a large 

area to the south of Volusia County. The 

St. Johns River is not considered in the 

water budget because flow in this river is 

along the edge of the county rather than 

through it.

Storage of Water in the Atmosphere

There is always some water in the 

atmosphere. Clouds are, of course, the 

visible condensation of atmospheric 

water, but even clear skies contain some 

water—water in particles that are just too 

small to be seen. 

The total amount of atmospheric 

water vapor in a vertical column of air 

(often called the precipitable water, or 

PW) is measured daily by the National 

Weather Service with radiosondes 

(weather balloons). The highest daily 

water-vapor content measured at the 

Kennedy Space Center radiosonde 

station (about 20 miles southeast of Volusia County) between 1983 to 2005 would 

be equivalent to a water depth of about 

2.6 in. (inches) on the Earth’s surface 

(fig. 3). This is less than the amount of 

rainfall that can be produced from a single thunderstorm in just a few minutes! 

Thunderstorms often produce amounts of 

rain that exceed the water-vapor content 

of the overlying atmosphere. This excess 

of rainfall over water-vapor content can 

occur because colliding air currents can 
10

100

1,000

10,000

1

ATMOSPHERE LAKES AQUIFERS

WATER STORAGE, IN INCHES

Figure 4. Estimated average water storage in Volusia 

County. (Amount of storage is equivalent to depth of water 

over the entire surface of Volusia County. Each horizontal 

line represents 10 times more water than the line below it).

EXPLANATION

RAINFALL–53 inches

STREAMFLOW–11 inches

GROUNDWATER FLOW–0.7 inches

EVAPOTRANSPIRATION–39 inches

SPRING AND FLOWING WELL DISCHARGE–2.3 inches

Figure 5. Annual water 

budget for Volusia County 

(adapted from Rutledge, 

1985). All quantities except 

rainfall are outflow from the 

county, and are in inches 

over the entire county.

bring additional water vapor from 

surrounding areas into the storm.

The average daily atmospheric 

water-vapor content, based on data for 

1983 through 2005, is equivalent to only 

about 1.3 in. This is a relatively small 

amount of water as compared to the 

amounts of water contained in surfacewater and groundwater storage. Although 

the atmosphere may not be a great storehouse of water, it is the superhighway 

used to move large quantities of water 

from one location to another.

Storage of Water on the Land Surface

Lakes are the most important 

vessels for surface-water storage in 

Volusia County. There are at least 

239 lakes in Volusia County that are 

10 acres or more in size (Florida Board of 

Conservation, 1969). These lakes have a 

combined area of about 79,300 acres, of 

which the vast majority is linked to the 

St. Johns River that forms the western 

boundary of Volusia County. The total 

surface area of Volusia County is about 

768,000 acres. Therefore, the percentage of the land surface that is covered by 

lakes is about 10 percent. For the lakes 

that are not part of the St. Johns River, 

this coverage is only about 1.3 percent. 

The amount of water contained in 

lakes depends on the depth of the water 

in the lakes. Lake depths have not been 

documented for many of Volusia County 

lakes, so only an estimate of total lake 

water volume can be made. While most 

lakes in Florida are shallow and average between 7 and 20 ft (feet) in depth 

(Fernald and Purdum, 1998), there are 

a few lakes of sinkhole origin which 

could be more than 100 ft in depth. For 

example, the assumption that an average 

lake water depth is 10 ft suggests that the 

total amount of water contained in 

all Volusia County lakes would be about 

35 billion cubic feet, which would be 

equivalent to a water depth of about 

12 in. distributed over the entire county.

Other surface-water features were 

not included in this estimate of surfacewater storage on the land surface because 

the areas or depths of water have not 

been documented. These include smaller 

lakes, wetland areas that contain water at 

least part of the year, and the water that is 

flowing in streams.

Storage of Water in the Ground

Underground water is stored in an 

aquifer, which is a layer of rock, sand, 

or other earthen material through which 

water can flow. There are two types of 

aquifers underlying Volusia County. The 

surficial aquifer system extends from the 

land surface to depths of 50 to 100 ft, 

and is composed mostly of sand, shell, 

and clay. Underlying the surficial aquifer 

system is the Floridan aquifer system, 

which is composed mostly of limestone. 

The two aquifers are separated in parts 

of the county by a layer of silt and clay 

which significantly slows the flow of 

water from one aquifer to another. The 

Floridan aquifer system extends to a 

depth of about 2,000 ft in Volusia County. 

Underlying the Floridan aquifer are rocks 

that are impermeable and, therefore, are 

not aquifers. A more detailed description 

of the ground-water system for Volusia 

County has been provided by several 

investigators, including Knochenmus and 

Beard (1971), Rutledge (1985), Kimrey 

(1990), and Williams (2006).

Most of the groundwater in Volusia 

County is contained within the Floridan 

aquifer system. Estimates of the amounts 

of water contained in this aquifer can 

be made by multiplying the volume 

(lateral area multiplied by thickness) by 

the porosity of the rock. Porosity is a 

measure of the relative volume of empty 

space within the rock that can be 

occupied by water. Porosity of the 

Floridan aquifer system is variable; 

however, an approximate average 

porosity can be used to estimate how 

much water is contained within the 

system. Scientists used an average of 

25 percent porosity in studies of groundwater flow in the upper part of the 

Floridan aquifer system (Davis, 1996), 

and thus estimated that the Floridan 

aquifer system is about 25 percent water. 

This volume of groundwater is equivalent to an astonishing 500 ft overlying 

the entire area of Volusia County. Much 

of this groundwater, especially near the 

coast and along the St. Johns River, is 

brackish; that is, it contains salt and is not 

suitable for drinking. 

A comparison of the amounts of 

water stored in the atmosphere, on the 

surface, and beneath the ground in Volusia County indicates that groundwater is 

by far the largest storage place for water 

(fig. 4). Groundwater probably accounts 
45

50

55

60

40

DAYTONA

ANNUAL TOTAL, IN INCHES

DELAND SANFORD CRESCENT

CITY

MEAN

(4 sites)

NOAA STATIONS

Figure 6. Average rainfall at Daytona, DeLand, Sanford, and 

Crescent City NOAA stations, 1923-2006.

The Water Budget: Moving Water In and Out of Volusia County

Figure 7. Average monthly rainfall at DeLand, Florida, 

1923-2006.

0

2

4

10

J F M A M J J A S O N D

1923-2006

MONTHLY TOTAL, IN INCHES 6

8

for more than 99 percent of the water 

in Volusia County. By comparison, the 

amount of water stored in the atmosphere 

is relatively insignificant. However, as 

the transporter of virtually all water into 

the county, the atmosphere becomes a 

very important feature, even though the 

atmospheric layer over Volusia County 

contains very little water at any one time.

rainfall events. In summer it is not 

uncommon for a thunderstorm to drench 

a particular neighborhood, while 

leaving areas a block or two away dry. 

On an annual or longer basis, rainfall is 

less variable from place to place, though 

differences do occur. For example, the 

average rainfall for the entire period of 

record common to all four stations (1923 

Evapotranspiration

Evapotranspiration can be estimated 

by a water-budget analysis, in which ET 

is the difference between the amount 

of rainfall and the amount of surface 

water and groundwater outflow (amount 

of water flowing away from Volusia 

County). Evapotranspiration accounts for 

the largest outflow of water from Volusia 

In the following discussion, the 

water budget shown in figure 5 is derived 

from Rutledge (1985). Although this 

water budget was developed more than 

20 years ago, it still is representative of 

current conditions (2009). More recent 

data on rainfall, streamflow, and evapotranspiration are used to illustrate seasonal and location-to-location variability 

of these components of the water cycle.

Rainfall

Rainfall provides practically all 

of the inflow of water to Volusia County 

(fig. 5). Based on four long-term stations, 

rainfall is estimated to average about 

53 in/yr (inches per year) over the entire 

county. However, rainfall can vary from 

place to place. Most of us have witnessed 

the short-term variability of individual 

through 2006) ranged from about 56 in. 

at DeLand, to about 49 in. at Daytona 

Beach (fig. 6). The reason for these 

differences from location to location in 

or around Volusia County is not clearly 

understood.

There is a definite seasonal pattern 

to rainfall in Volusia County. Summers 

are typically wet, although there can 

be dry periods of several days or a 

week or more between storms. Winters 

are typically dry, and an entire month or 

more can sometimes pass with no rainfall. This seasonal pattern is evident 

from the average monthly totals for 

rainfall at DeLand (fig. 7). Monthly 

total rainfall is generally between 2 and 

4 in. during all months except for June 

through September, when it is between 

7 and a little more than 8 in. 

County and is estimated to be about 

39 in/yr (fig. 5). 

 Evapotranspiration studies have 

been conducted at two sites in Volusia 

County using instrumentation that measures the amount of water vapor moving 

upward to the atmosphere. These studies 

also provide a range of the ET that can 

occur within the county. In 2002, one 

study at the Lyonia Preserve 

(fig. 2) determined that ET from a 

forested upland area was 42 in/yr. In 

contrast, ET from a wetland near the 

forested upland area was much higher, 

and was estimated to be 59 in/yr for the 

year (Knowles and others, 2005). Another 

study in a cypress and pine forest near the 

streamgaging station on Tiger Bay Canal 

(fig. 2) measured an ET rate of about 

38 in/yr in 1998-99 (Sumner, 2001). 
0

5

10

25

J F M A M J J A S O N D

2002

MONTHLY TOTAL, IN INCHES 15

20

RAINFALL–At Lyonia Preserve

EVAPOTRANSPIRATION–From

uplands at Lyonia Preserve

Figure 8. Monthly rainfall and evapotranspiration at Lyonia 

Preserve, 2002 (data from Knowles and others, 2005).

0

5

10

J F M A M J J A S O N D

1977-2006

MONTHLY TOTAL, IN INCHES

15

20

Figure 9. Average monthly total streamflow, Tomoka 

River near Holly Hill, Florida, 1977-2006.

Streams transport much more water out of 

Volusia County than they bring into the county.

Generally, ET rates are related to water 

availability at the land surface and within 

the upper soil layers, and are greatest in 

lakes and wetland areas, and lowest in the 

well-drained sandy ridge areas.

Changes in the amount of evapotranspiration on a daily or seasonal basis 

tend to be smaller than the variation in 

County. Another basin includes Deep 

Creek (north and south tributaries), Cow 

Creek, and other tributaries, and drains 

into the St. John River to the west. The 

other basin drains seaward and contains 

Tomoka River, Spruce Creek, and Tiger 

Bay Canal. Streamflows in Volusia 

County have been measured regularly by 

(fig. 5). Most of this groundwater 

outflow is from springs and flowing wells 

where groundwater is being discharged 

from the Floridan aquifer system to 

surface streams. The two principal 

springs in Volusia County, Blue Spring 

and DeLeon Spring, account for about 

2.0 in/yr. Rutledge (1985) estimated that 

rainfall. Extended periods of no rainfall 

can last for several weeks in the winter 

and spring, but ET occurs nearly every 

day. Also, unlike rainfall, extremes in 

daily or monthly ET are relatively not 

dramatic. For example, at the Lyonia 

Preserve, monthly rainfall in 2002 ranged 

from about 0.9 in. to more than 22 in., 

while ET ranged from about 1.8 to 5.6 in. 

for the same period (fig. 8).

Streamflow

Streams transport much more water 

out of the county than they bring into 

the county. Streamflow accounts for the 

second largest outflow of water from 

Volusia County, or about 11 in/yr (fig. 5). 

There are three major streamflow basins 

in Volusia County (fig. 2). One basin 

contains Little Haw Creek and Middle 

Haw Creek and drains north to Flagler 

the USGS at the streamgaging stations 

shown in figure 2, with records beginning 

in 1950 or earlier for some streams. 

There is a distinct seasonal pattern 

to streamflow, with lowest flows occurring at the end of the spring dry period 

and the highest flows occurring at the end 

of the summer wet period. Streamflow for 

the Tomoka River depicts this seasonality, with the 30-year average streamflow 

ranging from 2.1 in. during May to about 

20 in. during September (fig. 9).

Groundwater

Groundwater movement takes more 

water out of the county than it brings into 

the county. However, this groundwater 

outflow accounts for a relatively small 

amount of water, compared to the other 

components of the county water budget, 

and is estimated to be about 3 in/yr 

two small springs near Lake Monroe 

discharged an additional 0.1 in/yr, and 

that flowing wells discharged about 

0.2 in/yr. However, most of these flowing wells have since been plugged as 

a result of the abandoned artesian well 

plugging project of the St. Johns River 

Water Management District.

There is also subsurface movement 

of groundwater through the Floridan 

aquifer system into and out of the county. 

This subsurface flow at the county 

boundaries cannot be directly observed 

or easily estimated. Estimates by 

Rutledge (1985) indicate that about 

0.8 in. of groundwater flows into the 

county from adjacent counties, and that 

about 1.5 in. flows from the county, for a 

net subsurface outflow of about 

0.7 in/yr.
For more information contact:

U.S. Geological Survey

Central Florida Research Park

12703 Research Parkway

Orlando, Florida 32826

(407) 803-5531

The Human Role

Does human use of water affect 

the water budget of Volusia County as 

a whole? Water is pumped from the 

Floridan aquifer system for many uses, 

including drinking-water supply, crop 

and lawn irrigation, industrial uses, and 

recreational purposes. In 2005, an average of about 77 Mgal/d (million gallons a day) was withdrawn from Volusia 

County aquifers (Marella, 2008). This 

rate of water flow, which is equivalent to 

filling about 115 Olympic-sized swimming pools each day, could cover the 

entire Volusia County land surface to a 

depth of about 1.3 in. in a 1-year period. 

Thus, human usage of water is relatively 

small in comparison to the 53 in/yr that 

the county receives by rainfall. 

Some of this water returns to the 

ground after use as seepage from irrigated 

lawns and crops, septic tank drainage, or 

treated wastewater through land application and percolation ponds associated 

with wastewater treatment plants. Some 

of the water used for irrigation (about 

20 Mgal/d in 2005 according to Marella, 

2008) returns to the atmosphere as ET. 

small in comparison with the 53 in/yr 

that the county receives by rainfall. 

References Cited

Davis, H., 1996, Hydrogeologic investigation and simulation of groundwater 

flow in the Upper Floridan aquifer of 

north-central Florida and southwestern 

Georgia and delineation of contributing areas for selected City of Tallahassee, Florida, water-supply wells: U.S. 

Geological Survey Water-Resources 

Investigations Report 95-4296, 56 p.

Fernald, E.A., and Purdum, E.D., eds., 

1998, Water Resources Atlas of 

Florida: Institute of Science and Public 

Affairs, Tallahassee, Florida State 

University, 312 p.

Florida Board of Conservation, 1969, 

Florida lakes part III Gazetteer: 145 p.

Kimrey, J.O., 1990, Potential for groundwater development in central Volusia 

County, Florida: U.S. Geological 

Survey Water-Resources Investigations 

Report 90-4010, 31 p.

2001-2003: U.S. Geological Survey 

Scientific Investigations Report 

2005-5178, 82 p.

Marella, R.L., 2004, Water withdrawals, 

use, discharge, and trends in Florida, 

2000: U.S. Geological Survey Scientific Investigation Report 2004-5151, 

50 p.

Marella, R.L., 2008, Water use in Florida, 

2005 and trends 1950–2005: 

U.S. Geological Survey Fact 

Sheet 2008-3080, 6 p.

National Oceanic and Atmospheric 

Administration, 2007, Cape 

Kennedy, Florida: 1950 – 2005 XMR/

COF Surface-300 MB Precipitable 

Water: accessed May 28, 2008 at 

http://www.crh.noaa.gov/unr/include/

pw.php?sid=xmr

Rutledge, A.T., 1985, Ground-water 

hydrology of Volusia County, Florida, 

with emphasis on occurrence and 

movement of brackish water: U.S. 

Geological Survey Water-Resources 

Investigations Report 84-4309, 29 p.

Some treated wastewater is discharged 

to the St. Johns River, the Halifax River, 

and the Indian River, thus exiting Volusia 

County. Wastewater treatment plants 

serving DeLand and the coastal communities of Daytona Beach, New Smyrna 

Beach, and others discharged about 

15 Mgal/d to rivers in 2000 (Marella, 

2004.) This is equivalent to about 

0.3 in/yr for the Volusia County water 

budget. Thus, the amount of wastewater 

that is discharged from the county is 

Knochenmus, D.D., and Beard, M.E., 

1971, Evaluation of the quantity and 

quality of the water resources of Volusia County, Florida: Florida Bureau of 

Geology Report of Investigations 57, 

59 p.

Knowles, L.K., Jr., Phelps, G.G., 

Kinnaman, S.L., and German, E.R., 

2005, Hydrologic response in karsticridge wetlands to rainfall and evapotranspiration, central Florida, 

Sumner, D.M., 2001, Evapotranspiration from a cypress and pine forest 

subjected to natural fires in Volusia County, Florida, 1998-99: U.S. 

Geological Survey Water-Resources 

Investigations Report 01-4245, 56 p.

Williams, Stanley, 2006, Simulation of 

the effects of groundwater withdrawals from the Floridan aquifer 

system in Volusia County and vicinity: 

St. Johns River Water Management 

District Technical Publication SJ2006-

4, 218 p.

U.S. Department of the Interior

KEN SALAZAR, Secretary

U.S. Geological Survey

Suzette M. Kimball, Acting Director

Where will Volusia County get additional water?

By Edward R. German