A watershed is a given area of land that drains all of the precipitation in an area into streams and rivers that eventually lead to a larger body of water such as a large lake, the ocean, or, in this case, the Long Island Sound. The Long Island Sound watershed is all of the land and water area that feeds into the Sound. The states that are a part of the Long Island Sound watershed are New Hampshire, Vermont, Massachusetts, Rhode Island, Connecticut, New York, and even Canada. The Connecticut River is the largest river feeding into the Sound and its source is in Canada. This river picks up water from 11,263 square miles of land. The Thames and the Housatonic River basins together add another 3,500 more square miles of watershed to the Sound. No rivers flow from Long Island, but is still part of the watershed that feed the Long Island Sound. The Long Island Sound watershed drains over 15,00 square miles. Winter snow collects on hills and mountains in the New England states. Therefore, levels are lowest for feeding the rivers. When spring comes and the snow melts, levels rise. This causes a spike in water runoff and is referred to as the spring freshet. Rivers provide ninety percent of the freshwater that flows into the Sound.
The Long Island Sound is an estuary, which is a mix of fresh and salt water. The Sound gets its salt water from the Atlantic Ocean and gets its fresh water from the three largest rivers, the Thames, Housatonic, and the Connecticut Rivers. Long Island Sound separates Long Island from Connecticut. The formation of the Sound occurred through glaciation that occurred during the ice age. The glacier cut through hills and land. The weight of the glacier pressed down the land causing a deep groove. When the glacier eventually melted, it formed a freshwater lake. Over time, through erosion from wind and water, the eastern part of the lake opened up to the Atlantic Ocean creating a mix of fresh and salt water forming an estuary we know today as the long Island Sound. This area is known as the Race. The Race is where there is the most turbulent place on the Long Island Sound, where as the rest of the Sound is rather calm. The Long Island Sound watershed was home to many Native Americans who fished and caught game such as deer and pheasants. Then in 1614, Dutch explorer Adriaen Block finished his exploration of the Long Island Sound. His business was fur trading. This opened up the Sound for trade. Dutch settlers inhabited Manhattan Island at the mouth of the Connecticut River. They were soon displaced by English settlers. European settlers, mainly the Puritans, soon cleared the land for farming, trade, fishing, and whaling. The Native American influence dwindled by the late 1600’s.
Commerce grew and this area became home to brass and metal finishing, textiles, hat manufacturing, and fishing for oysters. These commercial businesses put a toll on the Sound and its tributaries. When the Industrial Revolution happened around the 1790’s to the 1830’s. This caused a growth in population and pollution. The New Haven Harbor has been dredged, periodically due to silt being deposited by rivers. The dredged soil from the Harbor was dumped onto land increasing the land mass in New Haven, CT. In the 1950’s the population rose again due to post war housing development. This is also the period of time that water quality testing began to see how humans impacted the environment.
One of the major problem is a decrease in dissolved oxygen, killing organisms that live in the water. This is caused by increased levels of nitrogen, a nutrient that plants thrive on. This condition is known as hypoxia. It causes an overproduction of growth among plants, algae and plankton. This overproduction of plant and plant-like organisms then leads to death and decay, which in turns, leads to a growth in the bacteria that consumes the dead and decaying organisms and these bacteria use up the oxygen in the water. Some of this decrease in dissolved oxygen is a natural process, but efforts are being made to decrease human impact. The natural occurrence known as natural stratification happens in late summer where the surface water is warmed and floats on top of the more dense colder, saltier water which sinks. These distinct density levels is known as pycnocline .and it keeps the two layers from mixing.
In the 1970’s, the Clean Water Act was established. In 1985 Congress established the Long Island Sound Study (LISS). In 1994 the LISS adopts the Comprehensive Conservation Management Plan (CCMP) to restore and protect the Sound. The plan was to reduce toxic substances and pathogens, look into the hypoxia dilemma, and to protect natural habitats. In 1998, Connecticut, New York, and the Environmental Protection Agency (EPA) set limits on the amount of human sources of nitrogen pollution and to restore 2,000 acres of natural habitats. In 2001, the EPA approves New York and Connecticut’s goal of reducing “Human Maximum Daily Load” of nitrogen to the Sound. In 2003, the LISS adopts the Long Island Sound Agreement to contribute to the health of the Sound by 2014, four hundred years after Captain Block finished his exploration of the Sound.
In 2008, LISS establishes the Sentinel Monitoring Work Group to examine the effect of climate change in different areas of the Sound and its coast. The LISS is also responsible for uncovering the fact that nonpoint source of pollution biggest contributor comes from the drainage basin into the Sound.
In New York harbor, sewage contains compounds that combine directly with the oxygen and deplete it from the water. Eventually, the bottom waters are stripped of oxygen and the coastal sea dies. Unfortunately, the cost of eliminating the nutrients is so great, that it is not clear that society is willing to pay the price of cleanup. Right now, the trend is discouraging, our waters are losing more and more oxygen.
In 1992, 93,600 tons of nitrogen was dumped into the Long Island Sound per year. Out of that, 39.900 tons occur naturally and cannot be controlled. The remaining 53,700 tons come from human activities such as sewage being dumped into the Sound. This type of pollution is known as point source pollution.