• Also called a drainage basin.
• An area of land through which rainwater drains by flowing across, through, or under the soil surface to a common low point (definition from ACES)
• Every body of water has a watershed.
• Includes the land, air, water, and living things in a location
• Can drain into a larger stream, lake, wetland, estuary, or the ocean
• Different watersheds are separated by higher areas, called ridges.
• Smaller watersheds separated by lower ridges can be contained within larger, major watersheds.

• Tennessee River drainage in the northern part of the state
  • Drains a small portion of Alabama's land area
  • Contains the Tennessee River, Pickwick Lake, Wilson Lake, Wheeler Lake, and Lake Guntersville
• Mobile River Basin in the central part of the state
  • Drains over half of the state
  • Contains the upper Tombigbee River, Black Warrior River, lower Tombigbee River, Cahaba River, Coosa River, Tallapoosa River, Lake Martin, Weiss Lake, and Smith Lake
• Coastal Drainages in the southern part of the state.
  • Contains smaller river basins that empty into the Gulf of Mexico

• A river is a natural flow of running water that follows a well-defined, permanent path, usually within a valley. (definition from Encyclopedia.com)
• A stream (also called a brook or a creek) is a natural flow of water that follows a more temporary path that is usually not in a valley. (definition from Encyclopedia.com)

• When precipitation falls, water collects in streams
• The first streams to form are called headwater streams (or 1st order streams)
• When two 1st order streams meet, a 2nd order stream is formed
• When a 2nd order stream meets with another stream, a 3rd order stream is formed
• Rivers are larger streams of water that flow through a channel towards the sea.
• Smaller streams that flow into major rivers are called tributaries.

• Headwaters flow quickly through shallow channels over steeper land.
• Farther downstream, the land is less steep, and waters tend to flow more slowly in deeper channels.

Different aquatic organisms are able to survive in different parts of streams called microhabitats (smaller unique habitat within a larger habitat or ecosystem).

• Riffle: shallow area of stream that flows quickly over rocks
• Run: area of stream that flows smoothly
• Pool: deep areas where water moves slowly and deposits fine material

• Some organisms live on or under the stream bottom.
• Streams may have a rocky surface underneath, sandy bottoms, or some have areas with fine particles.

• Each of these materials provides a different type of habitat suitable for different aquatic organisms.
• A riparian zone is an area directly next to a stream including the area where water can overflow. Many organisms live in these areas.

• The rivers and streams in the northern part of the state tend to have clear, fast flowing waters over hard, rocky stream bottoms. In places where the terrain drops, rapids are formed.
• As some of these streams connect further south in the state, the channels begin to widen while the land becomes flatter.

• Streams in the southern part of the state are often wider and slower moving with sandy bottoms.
• These rivers move slowly through wetland or swamp areas surrounded by forests and appear dark in color.
• The dark color is a result of decomposition of dead plants that release chemicals called tannins which stain the water.

Many of Alabama's rivers and streams are known for their high diversity of freshwater fishes and snails.

• The Alabama River has one of the richest freshwater mussel beds
• The Cahaba River has more fish diversity than any river its size in a temperate climate
• The Choctawhatchee River has no major dams, so the freshwater snail diversity remains high
• The Coosa River watershed contains 5 of Alabama's ecoregions. Because it covers so many different types of terrain, the biodiversity in the Coosa River is high.
• The Sipsey River (sometimes called the Sipsey River Swamp) is a swamp stream that contains one of Alabama's largest wetland regions and is high in mussel diversity.

Ponds:

• Ponds are small and shallow and keep a constant temperature throughout the pond.
• Sunlight is able to reach the bottom of the pond, allowing plants to grow throughout the pond.
• These plants play an important role as the producers of the aquatic (water) food chain.

• Lakes are larger and deeper, giving them a range of temperatures depending on depth of the lake.
• Shallow areas near the edge of the lake share similar characteristics to ponds.
• Toward the center of the lake, the water becomes deeper.
  • Sunlight can reach the top portion of this region but not the deeper portions
• Certain organisms are specifically adapted to live on or under the lake bottom.

• Aquifer: Underground soil or rock saturated with water that can be pumped to the surface for use by people.
• Spring: A place where ground water meets and emerges from the land.
• Bog: Area of soft, water saturated ground. Substrate/soil is acidic and usually composed of sphagnum moss and peat which gives it a spongy texture.
• Marsh/Swamp/Wetland: Land that captures, stores, and slows movement of water. Land is constantly wet.
• Salt marsh: Coastal grassland that is frequently covered by the tide.
• Estuary: Where the mouth of a large freshwater river meets the saltwater from the sea.

Encyclopedia of Alabama