Spring 1996: Watershed Management

In the last issue of Update, we began to talk about nonpoint sources of pollution and how they impact the Sound. In that issue, we focused on nonpoint pollution as it relates to low dissolved oxygen, noting that nonpoint sources contribute over 20% of the total nitrogen load, making it a significant contributor to the hypoxia problems that plague the Sound each summer.

However, the impacts of nonpoint source pollution go beyond nitrogen and low dissolved oxygen. Some of the other problems that polluted runoff cause in the Sound include:

• Toxics: Toxic substances of concern in the Sound include some metals, pesticides, PCB’s, and hydrocarbons. These substances originate from a variety of sources including industry, agriculture, home use and the burning of fossil fuels, trees, trash and even charcoal barbecues. At high concentrations, toxics can kill fish, shellfish and other aquatic organisms. Toxics can also bioaccumulate in the tissue of fish and shellfish and in humans that consume contaminated seafood. As a result toxics may affect both human and ecological health, and can result in fish advisories and restrictions on consumption of fish and shellfish.
• Pathogens: Pathogens are disease causing organisms such as bacteria and viruses. They originate from water fowl and animal waste, septic systems, stormwater runoff, sewage treatment plant breakdowns, and improperly or untreated sewage discharges from the combined sewer overflows. To protect human health, when indicators of pathogens are found in the water column, beaches and shellfishing areas are closed to the public.
• Trash: Debris wash off the streets and are carried into the Sound in stormwater runoff, and are also directly deposited by boaters and beachgoers. Debris that find their way into the Sound include plastics, metal, glass, paper, wood, rubber, and cloth. Seventy-five percent of floatable debris in LIS consists of plastics. Floating trash diminishes our enjoyment of the water and can injure or kill wildlife that become entangled in or eat the trash. The total quantity of floatable debris and trash in the Sound decreases from west to east, probably due to decreasing population densities.

To view the full Spring 1996 newsletter, download the pdf document