1-in-10 Year Drought: A drought of such intensity that it is expected to have a return frequency of once in every 10 years. In other words, there is only a 10 percent chance (1 in 10) that less than this amount of rain will fall in any given year.

Acre-foot: The volume of water that covers one acre to a depth of one foot; 43,560 cubic feet; 1,233.5 cubic meters; 325,872 gallons. One foot of water on Lake Okeechobee is equivalent to about 450,000 acre-feet when the lake's water level is 15 feet NGVD.

Adaptive Management: The application of scientific information and explicit feedback mechanisms to refine and improve future management decisions.

Advanced Treatment Technologies: Biological and chemical treatment technologies to remove phosphorus from stormwater to achieve low concentrations once treatment is complete.

Alternative Water Supply: A supply of water that has been reclaimed after one or more uses, such as public supply, municipal, industrial, commercial or agricultural uses. The term can also apply to storm water, brackish water or salt water that has been treated in accordance with applicable rules and standards to serve the intended use.

Anoxic: The absence of oxygen.

Aquifer: An underground bed or layer of earth, gravel or porous stone that holds water.

Atlantic Multidecadal Oscillation (AMO): A cyclic variation in the large-scale atmospheric flow and ocean currents in the North Atlantic Ocean. They combine to alternately increase and decrease Atlantic sea surface temperatures (SSTs). Cool and warm phases that may last for 20-40 years at a time have a difference of about 1°F between extremes. These changes have been occurring for at least the last 1,000 years.


Basin (Groundwater): A hydrologic unit containing one large aquifer or several connecting and interconnecting aquifers.

Basin (Surface Water): A tract of land drained by a surface water body or its tributaries.

Best Management Practices (BMPs): Agricultural or other management activities designed to achieve an important goal, such as reducing nutrients or pollutants in runoff or optimizing water use.

Biscayne Aquifer: A portion of the Surficial Aquifer System that provides most of the fresh water for public water supply and agriculture within Miami-Dade, Broward and southeastern Palm Beach counties. It is highly susceptible to contamination due to its high permeability and proximity to land surface in many locations.

Boulder Zone: A highly transmissive, cavernous zone of limestone within the lower Floridan Aquifer.

Brackish: Water with a chloride (salt) level greater than 250 milligrams per liter (mg/L) and less than 19,000 mg/L.

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