Nitrogen Pollution


This element, which in its gaseous form is the most abundant component of air, is necessary to all life for the production of proteins and reproduction. Nitrogen occurs in nature in many forms, as a gas or as organic and inorganic material, and may be converted back and forth, or cycled through any of the three forms. The nitrogen cycle is the process whereby nitrogen passes from the atmosphere into living things, through the food chain, and ultimately back into the atmosphere.

Nitrogen is a fertilizer, utilized for growth by both plants and animals. In the oceans and estuaries, it is considered a limiting nutrient-some nitrogen is needed but a little goes a long way. When there are the proper amounts of nitrogen in the water, there is an appropriate balance between the growth and decay of plants, allowing the animals which rely on healthy plant growth and good water quality to thrive. Among other things, plants provide oxygen by photosynthesis to the water column, thus sustaining the populations of animals which reside there. However, too much nitrogen can result in blooms of algae, both within the water column and growing on the bottom. Excessive algal growth can block vital sunlight from reaching underwater plants such as eelgrass, which provide food and habitat for many species. It can cover shellfish beds, essentially choking them by interfering with their ability to filter water. As algae die, they sink, adding to biomass covering the bottom. Bacteria which feed on the algae as part of decomposition take up oxygen from the water. If decomposition occurs more rapidly than photosynthesis, oxygen levels can decrease to a level where animals can no longer survive. In addition, decaying algae can create foul smells and unattractive floating or bottom mats, reducing the aesthetic value of an area.

One of the most common pathways by which nitrogen enters oceans and estuaries is by surface runoff, especially as storm water. Fertilizers, road contaminants, septic systems, animal waste, and the atmosphere all contribute nitrogen to water bodies. By controlling the types and number of sources, as well as the amounts of nitrogen pollution, we will be better able to achieve that proper balance that is needed for a healthy water system.

Ecosystems: Working with farmers to decrease Nitrogen pollution from Environmental Defense Fund on Vimeo.


Nitrogen in the Westport River

The Massachusetts Estuaries Project Report for the Westport River Watershed will shortly be released to the public and made available on the MEP website:

This report is the result of a collaborative effort between many groups, principally UMass Dartmouth and the Massachusetts Department of Environmental Protection (MassDEP). This project was developed to help guide towns in their assessment and management of their coastal rivers and bays, which is required by the federal Clean Water Act. Many bays have pollution levels that are greater than what the bay can handle, and this may lead to poor water quality and loss of fish, shellfish and eelgrass. This decline in health has environmental, social, and economic impacts. For the Westport River, the pollutant of concern is nitrogen.

Preliminary results of the study show that the Westport River is experiencing a level of nitrogen pollution that is threatening the health of the river and its ecosystem. This is important information because the River is a critical component of not only the Town of Westport, but of the region as well.  As the River lives, so does the culture, economy, ecology, history, and community of Westport. Even if you are one who rarely sees or uses the Westport River, its value influences the Town’s welfare by supplying beneficial “services” to the area. The waters, marshes, and wetlands of the River provide sediment and flood control, water filtration, tourism, commercial fishing, recreation, economic and education opportunities, ecological diversity, and esthetic value.

For most of its existence, the River has been able to deal with the amount of nitrogen entering its waters while experiencing few negative impacts. Unfortunately, that is no longer true. The loss of eelgrass from areas of the River where it was once healthy is a key indicator of declining water quality, as are the summer algal blooms and periodic fish kills.

This report provides a significant opportunity for the community to engage in helping to “clean up” the River. The work of the Westport River Watershed Alliance has provided the critical water quality data, much like a doctor’s report. However, the Town of Westport must determine the approaches and means for restoring the River to healthy conditions. The involvement of the community, through support, participation, interest, and awareness will go along way towards achieving solutions to the pollution that will best benefit not only the River and its watershed, but the residents and visitors of this area as well.

There will be numerous opportunities in the coming months to learn about and/or get involved in the nutrient management planning process.

WRWA has started to work with the Westport Agricultural Commission to “tighten up” some of the agricultural statistics used in the report and explore ways to better control nitrogen which would benefit not only the River but the farmers as well. Additionally, WRWA supported the creation of the Community Septic Management Program, which was accepted at Town Meeting in May. This program will aid residents with failing septic systems by providing low- interest loans for those who replace their system with a conventional Title V system, or no – interest loans for those who opt for nitrogen-controlling septic systems. Both systems control bacterial pollution, but only the second option will help reduce nitrogen pollution to the River.

(To read more about how WRWA and the Town are working together on pollution problems, click here)

The study of the Bread and Cheese Brook, scheduled to begin in July, will enable the Town to narrow in on the specific sections of the upper watershed where nitrogen is highest and provide data that will be used to model the effectiveness of nitrogen reducing actions in these areas. Although the efforts of the entire Westport community are vital to cleaning up the River, addressing the known, measured sources of nitrogen will provide the most cost-effective, timely solutions to nitrogen pollution.