Ask The Experts

The boundaries of the Chesapeake Bay Watershed.The Ask The Bay Experts panel is comprised of Chesapeake Bay experts in many diverse fields of Bay issues including wetlands, pollution, watershed management, shad restoration, fish passage, fisheries, lawn care for Bay repair, blue crabs, monitoring, SAV and more. They work in a variety of academic institutions, non-profit organizations, federal/state government in the Bay watershed and Bay-related businesses.

How do changes in the health of the Bay affect blue crabs over time?
Pollution in the water of the Bay is as bad for the blue crab as standing next to a person smoking a cigarette or next to the exhaust fumes of a city bus is for you! As you might develop illnesses due to the polluted air you are breath, so do the blue crab develop problems when the water they live in is polluted. Their numbers decline, they reproduce less often and many do not survive to adult sizes. Just as you need clean air to breath, in order to develop into a healthy adult, so do crabs need clean water to do the same.

How does the water get into the Chesapeake Bay?
The water in the Bay comes from the many rivers, creeks and streams that make up its 64,000 square mile watershed which includes parts of six states, PA, MD, VA, WVA, DE, NY and Washington, D.C. Runoff from rain and snowmelt feed these tributaries of the Bay. Water also falls directly in the Bay in the form of rain and snow. It receives almost half its water from the Atlantic Ocean. Of the rivers that feed the Bay, the Susquehanna provides the largest amount of freshwater.The bay is an estuary, an area where salt and fresh water mix. For more information, read the online booklet: Introduction to an Ecosystem at:

How efficiently does the freshwater of Chesapeake Bay mix with the salt water of the Atlantic Ocean?
The mixing of the Atlantic salt water with the fresh water of the Bay varies from season to season and from year to year. Fresh water is lighter tends to ride on top of denser, salty ocean water. The salt water tends to flow into the Bay and move upstream below the warmer freshwater layer which flows over it and out into the ocean but this flow is directly affect by season, weather and temperature. All of these play a role in the mixing of the waters of the Bay and the ocean. The section on Water: Salinity, Temperature and Circulation in the online book, Introduction to an Ecosystem answers that question very thoroughly. Go to:

I am doing a school project on water testing. What tests should I perform?
You could perform tests for ph, temperature, dissolved oxygen, nitrogen and turbidity. You could check for the various Macroinvertebrates that exist in your stream in different times during the year. For more information go to: where the VA Save Our Streams organizations has Stream Doctor tools.

I have heard that pet waste from people not cleaning up after their pets contributes to the nutrient problems in the rivers that drain into the Bay. Is this true?
Pet waste, when not disposed of properly, is one of many small sources of pollution in local waterways. Waste left to decompose on streets or in vegetated areas near streets or water may be washed into storm sewers which flow into our river and end up in the Bay. Waste that decays in water uses up oxygen and can release ammonia, both of which when combined with warm temperatures can kill fish. The nutrients it contains can encourage excess algae growth and the organisms it may carry can make water unsafe for swimming or drinking.

Planting Bay grasses by hand is labor intensive. Is there a mechanical grass planting machine?
Visit for a view of a converted strawberry planted used to repair prop scars in grass beds in Florida. There is also a trademarked method called TERFS, or Transplanting Eelgrass Remotely with Frames Systems which was developed at the Univ. of new Hampshire which is cost effective and protects against bioturbation. View TERFS at

What is the difference between a watershed and a drainage basin?
A good definition comes from the Univ. of Calif Hydrology Dept., Fact Sheet No.33. Basic Concepts: Hydrology, the Hydrologic Cycle, Watershed, Watershed Management, and Watershed Water Balance. “There is often confusion concerning watershed vs. drainage basin vs. catchment. Technically, a drainage basin or catchment is the area of land that drains water, sediment, dissolved materials, and biota to a common outlet at some point along a stream channel. If the area is large (hundreds of square miles) it is a drainage basin, if it is small (acres to square miles) it is a catchment. We define a watershed as the area of land that drains water, sediment, dissolved materials, heat, biota, etc., to a common outlet at some point along a stream channel (watershed outlet). A watershed is a naturally delineated unit of land. Watersheds are the basic land unit of the hydrologic cycle, just as pastures are the basic land unit of a ranch. All of the land on Earth is in a watershed.” The Center for Watershed Protection has a good definition at:

What is a riparian forest buffer?
A forest buffer is an area of trees and vegetation that can intercept surface runoff, subsurface and groundwater flow while removing the effects of nutrients, pesticides and other chemicals that could enter our streams, rivers and lakes. Buffer zones can filter out much more sediment, pesticides and nutrients than grass turf. Mature trees along a stream bank can effectively use and buffer excess nutrients before they reach the water. Buffer zones control stream bank erosion, regulate water temperature, remove sediments and nutrients, reduce downstream flooding, provide wildlife habitat and increase property values.

What options are there to paved parking lots in order to reduce runoff?
Porous paving blocks are one alternative. Porous paving asphalt is another. Cobbles, gravel, mulch and natural stone are other alternatives. A fact sheet (Fact Sheet #4) on Alternative Pavers is available at

Why are underwater grasses so important?
These native grasses, called Submerged Underwater Vegetation, provide safe harbor and habitat for many Bay creatures, juvenile fish and Blue Crabs use them for shelter. They also absorb nutrients that can cause harmful, excessive algae growth in the Bay. Grasses protect shoreline banks from erosion by absorbing waves before they reach the shoreline. Grasses trap suspended sediment that can cloud the water and as green plants they provide oxygen, a critical element for water in the Bay. When algal blooms occur, due to excessive nutrients in the water, underwater Bay grasses die from lack of sunlight. Their decomposition consumes oxygen; this harms or kills off the animals that need oxygen in the water to survive. Restoration of native underwater Bay grasses is underway by many watershed organizations and groups.

Why is it important to measure salinity, pH, conductivity and temperature in the Bay?
These four items are all indicators of water quality. Measuring these levels just once will give a current indication of water quality. Measuring these levels and monitoring a stream, river or bay over a longer period of time permits a more detailed study of both the seasonal/yearly/monthly changes in water quality and the environmental factors which caused the change. A rise in conductivity levels can indicate increased levels of pollutants from runoff and wastewater systems. Salinity levels are critical to the survival of aquatic plants and animals as many species can survive only within certain salinity levels. Changes in salinity affect the variety of species found in a waterway. Aquatic species have preferred temperature ranges. As water temperature changes too far above or below that range, aquatic life decreases. Temperature also impacts oxygen levels in water., as water gets warmer, it holds less oxygen, making survival difficult for some forms of aquatic life. The pH of water determines whether aquatic life can survive in it. It measures solubility and availability of chemical constituents and heavy metals in water.

Why is the Bay polluted?
Many factors cause water pollution. Fertilizers, run-off from parking lots, improperly treated sewage, auto/boat/factory/plane/lawn mower/power plant emissions, boat waste, toxic chemicals in discharged water, erosion, nutrients from farm runoff and other factors. Air also carries pollution from the Midwest into the Bay watershed. The Chesapeake Bay watershed is 64,000 square miles but the Bay airshed is five times larger and includes the states of Ohio, Kentucky, Indiana, Tennessee, North and South Carolina and southern parts of Michigan and Canada. Air pollution from these areas can blow into the watershed and wash down through rainfall and snowmelt into the Bay. The Chesapeake 2000 Agreement focuses on pollution reduction. There are many things an individual can do at home, school or work to protect the Bay. Email our Ask the Bay Experts for information on how you can help!

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