Other human activities along the coast and in the watersheds that have created problems in estuaries include:

- The use of a fast-flowing river for a power source can slow and reduce water flow, cutting down on the amount of fresh and salt water mixing in the spring and the fall, because spring and fall flows are held back in the storage dams.

- Pollutants put into streams and rivers make their way to the estuary and become a part of the food web.

- Decaying matter from industries and untreated sewage increase the demand on the available supply of oxygen and can smother healthy aquatic life. Shellfish are particularly sensitive to contamination from sewage because they filter its harmful bacteria (fecal coliform) and particles from the sewage and these become concentrated in their digestive systems.

- Infilling, such as causeway construction, upsets a balance that has taken thousands of years to develop. When parts of an estuary are filled in, flow patterns are upset, interrupting critical circulation patterns. Infilling can also cause erosion and the deposit of silt can greatly disturb parts of the ecosystem. Clam beds, for example, cannot tolerate significant amounts of silt. Infilling also buries salt marshes.

- The dyking of salt marshes for farmland has resulted in a loss of over 80% of Nova Scotia's salt marshes, where much food is produced for coastal fish. This kind of dyking has also caused coastal erosion.

- Dredging changes the shape of the estuary but only temporarily. Eventually water flows will move materials from other areas to fill the dredged area back in and dredging must be done again. By disrupting the balance between the flows and the sediments you can damage sensitive habitats not directly impacted by the dredging or dumping of the sediments. Full consideration has to be given to on site and offsite impacts.

- Construction of wharves, breakwaters, and bridges changes water currents often resulting in erosion on the upstream or up-current side, and deposition down current side. This construction work also affects the mixing actions of currents in estuaries.

- Wood, bark, debris and other wastes from lumbering, sawmills, and pulp and paper industries reduce the clarity of the water and the amount of sunlight reaching underwater plants. This debris can also overload the bottom waters, using up valuable oxygen, resulting in winterkills of fish.

- Chemical pollutants from household cleaning products, farming and industrial waste can kill or harm life in the estuary. In many food chains chemicals or pollutants are passed up through the system.

- Sewage and fertilizers from farming encourage the growth of algae that can produce a toxin called domoic acid. When this situation develops, the area will be unfit for shellfish or commercial aquaculture. Sometimes the extra nutrients can cause certain toxic microscopic plants (dinoflagellates) to flourish, making the water look red. This is called a "red tide".

- Tidal barriers Coastal wetlands have been dyked and flows restricted by undersized culverts and bridges for hundreds of years. This ahs resulted in extensive loss of wetland area, function, productivity, fish, fish passage, and in general fish and wildlife habitat. There are projects underway to restore these wetlands and prevent further losses. For more information contact the Ecology Action Center in Halifax http://www.ecologyaction.ca/coastal_issues/coastal_issues.shtm

- Coastal Squeeze - coastal development (rural, urban, commercial, infrastructure) can result in the loss of coastal wetlands by preventing the natural landward migration of coastal habitats in response to rising sea levels. Coastal development is drawing a hard-line in the sand and coastal features are being squeezed and lost.

Fortunately, estuaries tend to be quite resilient to chemical pollution and can recover quickly when the source of the pollution stops. The safest way to prevent ecological problems is to use preventive and enhancement procedures when considering development.

Here are some things for you and group to do:

- Get to know your estuary and its history. If you know the estuary well you will be more able to observe and be aware of changes.

- Make sure that natural flow patterns are not interrupted by development or work along the coast.

- Use environmentally friendly cleaning products in homes and businesses.

- Ensure that toxic chemicals are properly disposed of.

- Control the use of chemicals and fertilizers, especially near any watercourse.

- Make sure that too many nutrients don't get into the system through sewage and/or fertilizer run-off.

- Be certain there are low levels of bacteria in water that flows into the estuary. Chlorinating the bacteria away is not a good solution, as chlorine is toxic to young fish and shellfish.

For ways you can help the coastal ecosystems see "50 ways to save the Gulf of Maine"http://www.gpac-gom.org/Task Groups/50 Ways/webbook.pdf

Make sure you read the following sections on how to research and enhance your water area.