An abundance of algae results in cloudy water, which prevents Bay grasses from receiving the sunlight they need to live. Additionally, when the algae die, they are decomposed by bacteria that use up the oxygen dissolved in the water. Dissolved oxygen is very important to the survival of living resources in the Chesapeake Bay, and if it is depleted, the plants and animals that make their home in the Bay may die. Sediment is fragmental material derived primarily from the physical degradation and chemical decomposition of rocks. Sediment also is present naturally in the environment, and is transported to the Chesapeake Bay by its tributaries.
Sediment harms the Bay when present in excessive amounts.
Excess sediment enters the Bay from the erosion of farmland and construction sites, as well as in runoff from cities and suburbs. Excess sediment clouds the water and coats the leaves of plants, both of which deprive them of sunlight needed for growth. In addition, phosphorus and toxic contaminants, such as trace metals and pesticides, attach to sediment particles that are carried downstream and deposited into the Bay. The USGS monitors the amount of freshwater that enters the Chesapeake Bay each month. Relation of 46-year average January flow to January 1996 flow into the Chesapeake Bay.