Westport health notes: Keeping waters' nitrogen level low starts with you

By Phil Weinberg
Posted 5/11/23

OVERLINE: Westport Health Notes


Welcome to Westport Health Notes, a monthly column from the Westport Board of Health (BOH).   The goal is to share information with our community …

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Westport health notes: Keeping waters' nitrogen level low starts with you


OVERLINE: Westport Health Notes


Welcome to Westport Health Notes, a monthly column from the Westport Board of Health (BOH).  The goal is to share information with our community about local issues and projects, public health alerts, and even fun facts about the A-to-Z scope of responsibility that local Boards of Health manage. The May column is all about fertilizers.

The arrival of spring has not brought us a lot of sunny days so far, but that hasn’t kept flower beds from sprouting and lawns from greening. That is a welcome sight, but with it comes the risk of nitrogen and phosphorus pollution that the misapplication of commercial fertilizer brings to our river, ponds and streams.

It is estimated that over 4.3 tons a year of nitrogen from lawn fertilizer enters the Westport River from surface runoff and groundwater. Just as on land, nitrogen stimulates plant growth, but in this case, it’s taken up by algae that trigger blooms. This eutrophication process blocks sunlight and absorbs oxygen necessary for maintaining eelgrass beds. Although under water and out of sight, healthy eelgrass is essential to the quality of the river’s habitat that provides food, shelter and a nursery to the multitudes of aquatic life it supports. Excess phosphorus from fertilizer has the same stimulus impact on algae in freshwater ponds, but there the variety of blue-green algae that spreads during the summer months is toxic to humans and pets.

The regulation of nutrients for agriculture and turf/lawns is delegated by state law to the Massachusetts Department of Agriculture and does not allow for local regulations or bylaws unless they have been grandfathered (https://www.mass.gov/plant-nutrient-management). Homeowners and landscapers are required to comply with the MDAR regulations which incorporate UMass Amherst Guidelines. Lots of useful information can be found on their website at https://ag.umass.edu/home-lawn-garden/fact-sheets/fertilizing-guidelines. Some of the key restrictions provide that: No nutrients can be applied using a broadcaster within 20 feet of a waterway or 10 feet using a drop spreader; within a Zone 1 of a public drinking water well or 100 feet of a surface water used for a public drinking water supply; or to saturated soils or soils that frequently flood. Additional restrictions apply to fertilizer containing phosphorus unless the application is limited to once a year and in accordance with very low application rates and phosphorus concentrations.

If you choose to apply fertilizers, there are some steps you can take to reduce the amount and impact of their use. Don’t assume your lawn needs all the categories and amount of nutrients found in commercial fertilizers. Have your soil tested first — one good option is through UMass Extension: https://ag.umass.edu/services/soil-plant-nutrient-testing-laboratory. If additional nutrients are needed, chose a slow-release type that allows the soil to absorb the nutrients. Grass clippings left on the lawn are a good option. These two steps will prevent excess chemicals from running off into surface waters or seeping down through soil and into the ground water.

A more ambitious solution to using less lawn fertilizer is less lawn. Through “nature scaping,” all or portions of a lawn can be repurposed through the introduction of native plantings that are aesthetic as well as low in maintenance and water consumption. The conversion helps protect our waterways and creates habitat that attract beneficial insects and other wildlife.   

A second, more significant source of fertilizer’s adverse impact to the river comes from agricultural operations. An impressive demonstration of the nitrogen reductions that were achieved by Westport farmers comes from a report recently issued by Massachusetts Association of Conservation Districts. In cooperation with the town’s Agricultural Commission, MACD worked with six Westport farms to adopt infrastructure improvements and best management practices targeted to reduce manure runoff from being transported by storm and ground water into the river. As a result of their combined efforts, it was estimated that nitrogen pollution was reduced by 24 tons each year. These on-going reductions represent one-third of the total amount of nitrogen contributed to the river by agricultural sources. 

Congratulations and our appreciation to everyone involved in that project.

Weinberg is vice chairman of the Westport Board of Health.










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Jim McGaw

A lifelong Portsmouth resident, Jim graduated from Portsmouth High School in 1982 and earned a journalism degree from the University of Rhode Island in 1986. He's worked two different stints at East Bay Newspapers, for a total of 18 years with the company so far. When not running all over town bringing you the news from Portsmouth, Jim listens to lots and lots and lots of music, watches obscure silent films from the '20s and usually has three books going at once. He also loves to cook crazy New Orleans dishes for his wife of 25 years, Michelle, and their two sons, Jake and Max.