Nitrogen Pollution

New Hampshire’s coastal waters are in danger. In 2010, the New Hampshire Department of Environmental Services listed parts of the Bellamy River, Cocheco River, Exeter River, Great Bay, Lamprey River, Oyster River, Piscataqua River, and Salmon Falls Rivers as impaired or threatened by nitrogen pollution.

Why is this a problem?

Excessively high nitrogen levels in a water body can trigger explosive algae growth known as algal blooms. As the algae dies, it depletes dissolved oxgyen levels in the water and block out sunlight, potentially leading to a loss of habitat for fish and aquatic plants. This deadly process is known as eutrophication.

The Great Bay Estuary is already exhibiting signs of eutrophication:

• 42% increase in total nitrogen to the estuary load in just five years
  
• Adult oyster populations in the estuary have plummeted from 125,000 bushels in 1997 to just 10,044 in 2009.
• 1990-2008: 65% percent decline in eelgrass habitat
  

Source: Piscataqua Region Estuaries Partnership. State of the Estuaries 2009

Take the pledge to save Great Bay!

You can help! Join the more than 70 households who have pledged to do their part to help reduce nitrogen pollution from lawn fertilizers by either:

1. Not using nitrogen-based lawn fertilizers

2. Using only low phosphorus, slow release nitrogen lawn fertilizers that have the least impact on the estuary

Your Name:

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Did you use lawn fertilizers before taking this pledge?:

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Lawn Fertilizers and nitrogen

Most lawn fertilizers sold on the market today contain nitrogen, a nutrient that helps to promote grass growth. Unfortunately, not all of that nitrogen stays on your lawn. Nitrogen from lawn fertilizers can run-off into local rivers, streams, and estuaries, contributing to the problem of nitrogen pollution.

Fertilizer free lawn care tips:

Did you know that incorporating clovers into your lawn is a great way to block out weeds and supply your lawn with nitrogen safely and naturally? Download our new “Seacoast Nitrogen Campaign Home Action Kit” for more free tips!

Recommended Lawn Fertilizers

NH Coast recommends that you use only low phosphorus, slow release nitrogen fertilizers that meet the following criteria:

• No more than 2% phosphorus
• At least 50% of nitrogen made up of slow release components

How to Read A Lawn Fertilizer Label To Determine Nitrogen & Phosphorus Content:

Lawn fertilizers are labeled to provide consumers with information about nitrogen, phosphorus, and potassium content. This information is usually communicated in in the following format:

(Nitrogen-Phosphorus-Potassium).

For example, a label marked (15-1-3) would contain 15% nitrogen, 1% phosphorus and 3% potassium. This ratio is known as the guaranteed analysis.

To determine the percentage of phosphorus in a fertilizer, simply look at that magic middle number. If it is a 2 or below, you are good to go!

Determining the percentage of slow release nitrogen is a bit trickier. Information about the percentage of nitrogen that is slow release - if any - is usually found in small print located below the guaranteed analysis. The terms “water insoluble”, “slowly available”, or “slowly available soluble nitrogen” may be used as a substitute for “slow release” some cases.

Take the slow release fertilizer percentage and divide it by the total nitrogen content, then multiply by 100. The result will tell you the percentage of nitrogen that is slow release.

For example:

(10-2-1)

Contains 5% slow release nitrogen

5/10 X 100 = 50% of the nitrogen in this lawn fertilizer is slow release

Fact: The New Hampshire Shoreline Protection Act prohibits the use of all fertilizers but limestone within 25 feet of the reference line of coastal waters subject to the ebb and flow of the tide, including the Great Bay Estuary and associated tidal rivers. The reference line for coastal waters is the highest observable tide line, which means a line defining the furthest landward limit of tidal flow. Only slow release, low phosphorus fertlizers can be used within 50 feet of the reference line.

Program Sponsors:

This program was funded in part by a grant from the Piscataqua Region Estuaries Partnership, as authorized by the U.S. Environmental Protection Agency’s National Estuary Program.