North Carolina Water Systems

Rivers, Wetlands and Tidal Regions

River Basins• Three distinct systems– Flow to the Gulf of Mexico via the Mississippi• French Broad, Great Kanawha

– Flow to the Atlantic Ocean through South Carolina• Yadkin, Catawba

– Flow to the Atlantic Ocean through North Carolina• Chowan, Tar, Roanoke, Neuse, Cape Fear

What are River Basins• River Basin – portion of land drained by a river– Eventually empty into an estuary or ocean

• There are 17 river basins in North Carolina

• Drain 52,337 square miles of surface and underground water

• We ALL live in a river basin

Chowan & lower Roanoke Pamlico & Neuse Cape Fear

French Broad

New River

Pee Dee River Yadkin River Waccamaw Abbotts Creek Little Pee Dee (SC) South Yadkin Lumber Little Yadkin Lynches Ararat Little Elkin Rocky Fisher Coddle Creek Little Fisher Uwharrie Mitchell Little Uwharrie Mulberry

RoaringReddies

Santee (SC) Wateree (SC) Congaree (SC) Catawba Broad Lower Little Pacolet (SC) Middle Little North Pacolet Upper Little First Broad Johns Second Broad Linville Green Hungry Little Hungry

North Carolina Water SystemsEstuaries

What are Estuaries?• Places near the coast where freshwater and

saltwater mix• Influenced by both the ocean and freshwater

source– Tides, waves, major storms

• Time of day and length of the estuary influence the amount of salt– More salty at high tide– More salty closer to the ocean

How Did Estuaries Form?• North of Cape Lookout– Thick layers of sand, mud and peat deposited over

1.6 million years as different ice ages caused the rise and fall of sea levels

• South of Cape Lookout– Mostly rock covered by a thin layer of sand and

mud– Formed 90 to 1.6 million years ago

Types of Estuaries• Three types of estuaries in North Carolina– Trunk estuaries• perpendicular to the coast, in-line with the rivers that

feed them– Tributary estuaries• Flow into trunk estuaries

– Back barrier sounds• Parallel to the coast between the barrier islands and

the mainland shore

Why are Estuaries Important?

• Erosion and flooding control– Sand bars buffer waves– Plants and shellfish beds anchor the shore against

tides– Swamps and marshes absorb high winds and

water from heavy rains and storm surge• Gradually release this water into rivers and ground

water supplies

Why are Estuaries Important?

• Filter out toxins– Chemically• Aerobic respiration, sulfate reduction, methanogenesis• Salt marsh plants trap some chemicals and pathogens

and move them into soil where they are neutralized– Biologically• Feeding of estuarine animals and bacteria• Oysters that filter impurities out of water as they eat

trapping the impurities in their bodies

Why are Estuaries Important?

• Animal and plant habitat– More than 150 species of fish and invertebrates

live in North Carolina estuaries• Some species use different habitats within the

estuarine system during different stages of their life cycles

– Underwater plants cover about 200,000 acres on the coast of North Carolina• Submerged plants produce oxygen and nutrients used

by animal species

Why are Estuaries Important?

• Economic– Three quarters of the fish caught commercially in

the United States live in estuaries• on average estuaries produce more food per acre than

our most productive farmland– About thirty commercial fishing species live in

North Carolina estuaries• Commercial fishing is important to the national

economy and food supply.– Tourism and recreation

Threats to Estuaries• Land use changes

– Land is developed for human habitation and use, roads, bridges, culverts, sewage systems, pipelines, and dams• change the flow of water through the ecosystem

– wetlands soak up water like a sponge and settle contaminants in the ground

– asphalt and concrete deflect water so that it runs off with all its contaminants directly into the rivers, estuaries, and the sea

• Contamination of rivers and oceans– North Carolina estuaries contain 3,000 square miles of surface water,

but 30,000 square miles of land drains into the Albemarle-Pamlico • Dredging of channels damages plants and oyster beds and stirs up

sediment that clouds the estuary water• Since European colonization, nearly half North Carolina’s wetlands have

been lost, and coastal development continues to damage wetlands

Threats to Estuaries• Global warming

– causes sea levels to rise which threatens the swamp forests, which can withstand only temporary flooding

– hurricanes also cause high water levels - eroding the shoreline and flooding organisms adapted to freshwater with ocean water.

– Together sea level rise and storms cause North Carolina wetlands to erode at a rate of about 800 acres per year

• Excess of nutrients– sewage treatment plants, septic systems, polluted air, and fertilizers deposit

nutrients such as nitrogen and phosphorus in rivers and ultimately in estuaries– high levels of these nutrients can create large growths of algae called algal

blooms blocking sunlight– As algae dies its decomposition consumes oxygen which eventually suffocates

fish and invertebrates