An aquifer is an area underground that holds water in the gaps between rock, sand or gravel, sort of like an underground lake or stream.


An aquitard is an underground layer that water can’t move through easily. An aquitard, which might be something like solid rock or fine clay, can trap water in separate aquifers or force it to move in different directions.


Water changing from a gas into a liquid — this is how water vapor turns into clouds, fog and those drips that form on the outside of your cold drink.

Dissolved oxygen (DO)

DO measures how much oxygen is dissolved in the water. A high DO value means plenty of oxygen, which makes it possible for a lot of different animals and plants to live. Low values mean only a few specialized types can survive.


A drought occurs over a period of time when there isn’t much rain, or less rain than normal. Some plants are able to live without rain for much longer than others — they are called “drought-resistant.”


An ecosystem is like a neighborhood. It’s a community of plants and animals, including the physical environment they live in. An ecosystem might include a gopher tortoise, the nearby grasses that it eats, the dirt it digs a hole in and the coyote that tries to catch it.


Erosion happens when water and wind eat away at rock or soil. Thanks to gravity, erosion moves earth downhill and downstream. Over time, erosion can turn an entire mountain into mud on the bottom of a bay.


Water changing from a liquid into a gas (water vapor).


A substance (like manure) or chemical (like diammonium phosphate) that is added to soil to make plants grow better. People put fertilizers on their lawns, and farmers use fertilizers so they can grow crops over and over on the same land. Too much fertilizer can run off into streams or sink into the ground water.


A floodplain is the area of land that a river overflows when it is high. Rivers often dump lots of sediment on their floodplains, which makes these areas flat and excellent for growing plants. Until the next flood, that is!

Florida-friendly yard

A Florida-friendly yard doesn’t work against nature, but cooperates with it. Florida-friendly yards conserve water, are easy to maintain and don’t use a lot of harmful additives like pesticides and fertilizers. Florida-friendly yards often have a lot of Florida’s own native plants, which provide food and shelter for birds and butterflies.


The gradient of an area is the slope, or how much the land tilts. Steep areas have large gradients and water runs quickly over them. Flatter areas have small gradients where water moves very slowly.


Gravity is the force that pulls everything toward the center of the earth. So gravity is the reason that rain falls from the sky and water runs downhill.


Any water that has trickled into the ground; usually part of an aquifer.


Just inside the watershed divide, the highest parts of watersheds are the headwaters, where streams and rivers begin. The Green Swamp, northeast of Tampa, includes the headwaters of four major watersheds.


An herbicide is a substance, like a chemical, used to kill plants. People often use herbicides to kill plants they consider weeds.


Ground that isn’t porous is called impervious. Swimming pools are impervious, or they’d leak. Unfortunately, so are paved parking lots, roads and buildings, which means water has trouble sinking into the ground and charging aquifers in developed areas.


When lots of water sinks into the ground, it’s called “infiltration”. Areas of infiltration can “charge” the aquifer, which means they put more water into it. Since most of us get our drinking water from an aquifer, charging them up is very important!


Animals and plants are called invasive when they come from somewhere else and overgrow areas of Florida. Once they arrive and start to spread, many are impossible to remove and very expensive to control.


When we deliberately apply water to an area, we’re irrigating it. Farmers use irrigation to water their crops. You might use it to water your yard or garden. Water from irrigation could come from wells, or from dams, canals and pipes that change the course of surface water.


People build levees, which are mounds made of earth or concrete. We use levees to keep rivers from flooding, but that prevents rivers from overflowing into their natural floodplains.

Municipal water system

People who live in cities are usually too close together to have their own well and septic tank. Through a municipal water system, clean water arrives at their house in pipes, and wastewater is taken away — in a different set of pipes!

Native plants

Native plants are originally from an area, or have grown there for thousands of years. These plants are adapted to the local conditions and don’t require “help” from people to grow. They may also be important to local wildlife.

Nonpoint-source pollution

Nonpoint-source pollution is harder to trace because it comes from all of us — from our yards, pets, septic tanks and cars.


Pathogens, like bacteria or viruses, can cause diseases. An important part of good water management is trying hard to keep pathogens out of the water supply.

Percolate (diffusion)

When rain falls to the ground, the water can percolate through porous soils, moving downwards. Sometimes this is called “diffusion” — either way, it means the water is oozing through those little gaps in the ground.


Water moving through the ground by trickling between the little gaps in sand or rock. Usually water percolates downward from the surface into an aquifer.


A pesticide is a chemical used to kill animal “pests” like insects or sometimes rodents. Some people spray pesticides on their yards, and many farms use them.


PH is a scale from 0 to 14 that measures acidity. Most critters can tolerate a pH between 6.5 and 8.5 — lower numbers mean the water is too acidic, and higher ones mean it is too alkaline.

Point-source pollution

You can point your finger at the place where point-source pollution comes from, like a factory or power station.


The action can’t start unless the ground is porous — that is, full of little holes or gaps. Sand is porous, but much finer clay is not. Solid rock isn’t porous, but Florida’s limestones are usually full of cracks and holes that water can travel through.


Water falling from the sky as rain, snow, sleet or hail.


Riparian means along the shore of a river or some other type of water. Florida has a lot of rivers and lakes, so riparian ecosystems are very important here.


Runoff is liquid water that moves downhill across the earth’s surface, sometimes slowly (like in a swamp) and sometimes quickly (like in a waterfall).

Salt marsh

A salt marsh is a special ecosystem dominated by grasses that can live even when they get soaked by salty water. Florida’s coasts have salt marshes, which are very productive — some people call them “fish factories.”


Sediment is the rock or soil that comes from erosion and ends up as little chunks carried by water. Water that is carrying a lot of sediment is muddy looking. Eventually the water will clear as the sediment settles to the bottom, though that may not happen until after the water reaches the ocean.

Septic tank

A lot of houses, especially in the country, have a septic tank underneath their yard. Wastewater from the house goes into the septic tank, where microbes break down most of the grimy stuff. Cleaner water then seeps out into a septic field, where it gets even cleaner in the ground. If septic tanks are working, they keep wastewater from contaminating the area. To keep them working, they must be regularly inspected and maybe even pumped out once in a while.


When water moves slowly across relatively flat land, it’s called “sheetflow” because the water covers the land like a sheet. It happens in marshy or swampy areas when there are no channels (like a river). Florida, which has plenty of flat, swampy terrain, has more sheetflow than most places.


A spring occurs when ground water from the aquifer is forced to the surface of the earth.

Surface water

Surface water is any water on top of the earth, including lakes, rivers and even puddles. We use surface water for fun things like swimming and boating — and sometimes we treat it to make it safe to drink.


We know water temperature is important for swimming — it also affects dissolved oxygen, fish, plants and even microbes.


Water that gets drawn up in the roots of plants and then moves out of the leaves and into the air as water vapor. It’s kind of like the plants are drinking with their roots and then sweating with their leaves.


A tributary is a small stream or river that flows into a larger one. The more tributaries a river has, the bigger it gets.


Turbidity measures how clear the water is — or isn’t. Turbid water means there is a lot of debris, silt or other stuff floating around. That makes the water dark and murky, which makes it difficult for plants to grow and animals to breathe.


Clean water comes out of our taps, sinks and showerheads. After that, it becomes wastewater, which usually runs down a drain. Why is it wastewater? You might make it soapy, flush it, wash dishes with it or just leave the tap running — whatever happens, it turns from clean water into wastewater. So be careful not to waste water!

Water table

The point where the ground becomes saturated with water, which means all the little spaces are waterlogged, is called the water table. If the water table is close to the surface, you can't dig a hole without it filling in with water. Water tables in Florida are usually shallow — that's why you don't find many basements here.

Water treatment

Water, from wells or the surface, often needs to be treated to make it safe to drink. After we use it, municipal water systems usually bring wastewater into a wastewater treatment plant, which cleans the water enough to safely release it back into the natural water cycle.


A watershed is an area of land that water flows across or through as it moves toward a common body of water, such as a stream, river, lake or coast. Small watersheds like your own neighborhood can be part of huge watersheds, like the 1.5 million square miles that the Mississippi River drains.

Watershed divide

Watersheds are separated by higher land, like hills or ridges. The famous “Continental Divide” splits North America into two giant watersheds, but Florida's watershed divides are much flatter.


Think of a movie about the olden days. In the center of town is a circle of bricks with a little roof over it and a bucket that drops down into a hole in the ground. It’s a well — and we still use them, though in many places the bricks and buckets have been replaced with pipes and pumps. Houses in the country usually have their own wells, but in more crowded areas you might get your water from a well field.

Well field

An area containing one or more wells is sometimes called a “well field”. Tampa Bay has millions of people, so there are large well fields nearby to help provide water for everyone.