Explanation of Indicator
Florida’s coastal counties depend on their water resources for drinking water, agriculture, industry, and to support the many diverse natural systems found there. Unfortunately, nearly all human activities may adversely affect ground water quality and qua ntity in some way.
Agricultural land uses in the coastal zone may result in ground and surface water contamination and increased sedimentation if best management practices are not implemented. Agricultural uses include the irrigation of grasses, ornamentals, and commercial crops as well as non-irrigation withdrawal for purposes such as livestock drinking, wash down, and fish farming.
Data Characteristics
SOURCE
The Water Resources Division of the United States Geological Survey (USGS) is the lead office for this information. The USGS publishes a report, Water Withdrawals, Use, and Trends in Florida, every five years which contains these data. The report is pre
pared in cooperation with the Florida Department of Environmental Protection (DEP) and the water management districts. The publication is prepared by Richard L. Marella, who can be contacted at the USGS, 227 North Bronough Street, Suite 3015, Tallahassee
, Florida 32301, or at (904) 942-9500, extension 3004.
ACQUISITION
This information can be obtained in a hard copy format from the Water Resources Division of the USGS. There are no costs associated with obtaining this information.
COLLECTION
The information is collected statewide throughout the year by both DEP and the water management districts, and it is compiled by the USGS for the above-mentioned publication about every five years.
Data Limitations
This information is somewhat limited, first because it is compiled on a statewide basis approximately every five years. When data on quantities of water withdrawn are only displayed for every fifth year, anomalies may exist for a given year, which could
lead to an incorrect interpretation. If a given year has above or below normal precipitation (extremely wet or dry) or has an event like a hurricane, the water use value will most likely be skewed for that year. Second, in recent years, the data for thi
s indicator were calculated by multiplying the number of acres irrigated by the quantity of irrigation water required to optimally grow each crop and adjusted by computer modeling. Though these figures are estimates, they are believed to be quite accurat
e. For earlier years the figures are somewhat less accurate, primarily because the methods of data collection and modeling have improved over the years. Finally, not all water management districts require irrigators to meter and record their water use.
Since data collection is not required for all water management districts, the data may not reflect all agricultural withdrawals.
Data Analysis
Total agricultural water supply withdrawals more than doubled during the period of record, increasing from over 1,166 million gallons per day (mgd) in 1965 to nearly 2,405 mgd in 1990. During this period, ground water withdrawals increased 133% and surfa
ce water withdrawals increased nearly 87%. The biggest change observed between any two consecutive periods was for surface water between 1970 and 1975, during which time withdrawals increased 104%.
Year Ground Water(MGD) Surface Water(MGD) Total Withdrawal (MGD) 1965 489.22 677.47 1166.69 1970 701.75 611.88 1313.63 1975 651.35 1248.55 1899.90 1980 902.18 1113.93 2016.11 1985 941.37 989.73 1931.10 1990 1140.54 1264.41 2404.95