Understand exactly how salinity, temperature and also water circulation work together to kind the distinctive physical conditions in the Bay.

You are watching: Is the chesapeake bay brackish water


Salinity, temperature and also circulation space three vital physical characteristics of water in the Chesapeake Bay. Every of this physical qualities affects and is affected by the others.


Salinity is a measure of the amount of dissolved salts in the water. That is generally expressed in parts per thousands (ppt), or the variety of grams of liquified salts present in 1,000 grams of water.

Chesapeake just salinity

In general, the reduced Chesapeake bay is salty and also the upper Bay is fresh. Salinity slowly decreases together you move north, farther away from the ocean, and increases together you move south.

Salinity is greatest at the mouth of the Bay—averaging 25 to 30 ppt—where water native the Atlantic ocean enters.The head that the Bay and also its tidal rivers are fresh, with a salinity of less than 0.5 ppt.The middle part of the Bay and also its tidal rivers space brackish: a mixture of salt and fresh water. Brackish water has actually a salinity of greater than 0.5 ppt yet less than 25 ppt. Many of the water in the bay is brackish.

To check out salinity levels throughout the Chesapeake Bay, visit eye on the bay (for Maryland waters) or Virginia Estuarine and seaside Observing system (for Virginia waters).

Changes in salinity

Salinity varies extensively from season come season and from year to year, depending upon the amount of new water flow from the Bay’ rivers. The Bay often tends to be fresher in spring, when snow melts and also heavy rainstorms room frequent. During drier months, the just is normally saltier.

Salinity additionally increases with depth. New water stays at the surface due to the fact that it is less dense than salt water.

The water on the Bay’s east shore has tendency to be saltier 보다 water top top the western side, because of two factors:

Most fresh water enters the just from that is northern and western tributaries, including the Susquehanna and also Potomac rivers.The Coriolis Force, a phenomenon led to by the earth’s rotation, pushes flow water in the northern Hemisphere to the right. Therefore saltier water moving up the only veers towards the east shore.


Because the Chesapeake only is therefore shallow, it can not store warmth over time. Water temperature in the bay fluctuate commonly throughout the year, varying from 34 levels in winter to 84 levels in summer. Transforms in water temperature influence where underwater grasses have the right to grow and also when fish and also crabs feed, reproduce and migrate.

During spring and also summer, surface and shallow waters room warmer 보다 deeper waters. This create two distinctive temperature layers that physically separate deeper waters from surface ar waters. This temperature layers have actually a significant influence on dissolved oxygen levels in the summer.


Just as circulation moves blood transparent the human body, water transports crucial materials such as plankton, oxygen, minerals and also larvae throughout the Chesapeake Bay.

Circulation is mostly driven through the movement of new water indigenous the north and salt water from the south. Nutrients and also other crucial materials are mixed and resuspended in the area wherein fresh and salt water meet. This area is dubbed the ar of preferably turbidity. Numerous organisms usage this zone together a nursery area because of the lot of obtainable nutrients.

Weather—particularly wind—can disrupt or reinforce the two-layered flow of fresh and also salt water. Wind have the right to mix the water and also occasionally reverse the direction the flow. Wind can likewise raise or lower surface water levels.

Strong northwest winds connected with high pressure locations push water far from the Atlantic Coast and also create exceptionally low tides.Conversely, solid northeast winds associated with short pressure locations produce exceptionally high tides.Strong winds can additionally pile surface ar water versus one shore of the Bay.

How perform salinity, temperature and also circulation interact?

Together, salinity, temperature and also circulation dictate the physical features of water.

Warmer, lighter new water flows down toward the ocean. Listed below it, a layer of saltier and also denser water flows up the Bay. The 2 water layers room separated through the pycnocline: a ar of intensive mixing and rapid increases in salinity.

See more: What Senses Do You Use To Make Observations, How Children Use Sensory Observations In Science

Division of the 2 layers—called stratification—varies depending upon the season and also rainfall.

In spring, stratification is usually highest. Melt snow and frequent rain rise the amount of new water in the Bay.Throughout the summer, these stratified great are preserved as surface ar waters warm.In autumn, fresher surface ar waters cool much faster than deeper waters. The new water layer sinks and the two layers mix rapidly, normally overnight. This vertical mix does two necessary things: that moves nutrients up from the bottom, do them easily accessible to phytoplankton and also other biology closer come the water’s surface, and also it distributes oxygen come deeper waters.During the winter, water temperature and also salinity room relatively consistent from surface ar to bottom.