Bay Facts

The formation of the Chesapeake Bay happened 35.5 million years ago when a meteor collided with Earth, forming a massive crater.

Most of the water in the Bay, including in the middle portion of the Bay and its tidal rivers, is brackish–a mixture of salty and fresh, with a salinity level of greater than 0.5 ppt but less than 25 ppt.

The Bay receives about half its water volume from the Atlantic Ocean in the form of saltwater. The other half (freshwater) drains into the Bay from the enormous 64,000-square-mile watershed.

At filter feeders, oysters can filter up to 50 gallons of water a day.

Forty-six percent of watershed residents never use toxic pesticides in or around their homes. You can evaluate a pesticide’s toxicity to judge the risk in using it, or make your own non-toxic pesticide with garlic, vinegar, cooking oil and other common household items.

The surface area of the Bay and its tidal tributaries is approximately 4,480 square miles.

There were many different tribes in the region before Europeans arrived, but the dominant group were Algonquian speakers known collectively as the Powhatan tribes.

The Susquehanna River is the Bay’s largest tributary, and contributes about half of the Bay’s freshwater (about 19 million gallons per minute).

In 1524, Italian Captain Giovanni da Verrazano became the first recorded European to enter the Chesapeake Bay.

The area of the watershed is about 64,000 square miles.

The word Chesepiooc is an Algonquian word referring to a village "at a big river." In 2005, Algonquian historian Blair Rudes helped dispel the widely-held belief that the name meant “great shellfish bay.”

Eighty-six percent of watershed residents believe if people work together, water pollution can be fixed.

Mallows Bay is the final resting place for more than 200 historic shipwrecks dating back to the Revolutionary War. Commonly referred to as the “Ghost Fleet” of Mallows Bay, it is the largest collection of shipwrecks in the Western Hemisphere.

There are as many as 200 invasive species present in the Chesapeake Bay watershed that are causing some serious issues in an already-stressed ecosystem. Some examples include blue catfish, snakehead, zebra mussel, purple loosestrife, and nutria.

The Chesapeake Bay watershed contains three distinct geologic regions: the Atlantic coastal plain, the Piedmont plateau and the Appalachian province.

Major rivers emptying into the Bay include the James, York, Rappahannock, Potomac, Patuxent, Patapsco and Susquehanna from the west and the Pocomoke, Wicomico, Nanticoke, Choptank and Chester from the east.

More than 1,800 vessels have met their end in Bay waters, lying broken and battered on the Bay's floor.

There are twelve known species of shark that have been sighted in the Chesapeake Bay, with only five considered a common occurrence—smooth dogfish, sand tiger shark, sandbar shark, spiny dogfish, and bull shark.

The 110-mile-long Patuxent River is the longest river to flow exclusively within the borders of Maryland.