The Charles River has been the focus of clean up efforts. A recent bill could make it better than ever. Photocredit: Susan E. MacDonald, Wikimedia

The Environmental Protection Agency wants you to rethink your lawn. Or at least the stuff you put on it.

Let me explain. Many fertilizers have phosphorus in them, because phosphorus is an essential ingredient to all life, plant or otherwise. But this life-giving quality also has the potential to kill fish, poison water, and stunt the tourism industry, all through a process called eutrophication.

Eutrophication happens when large amounts of phosphorus or nitrogen end up in a body of water like a lake. Algae then blooms and uses up oxygen until the fish in the lake can no longer breathe. The blanket of algae also blocks sunlight and starves lake plants of sunlight. The blue-green algae that commonly cause the blooms can produce a toxin called Mycrocystin L-R, which is more poisonous than cyanide. Needless to say, this makes the water undrinkable. Usually, it’s Lake Erie that gets all the attention when it comes to eutrophication, but it’s also a problem in Massachusetts. A 2002 study found that the Boston Harbor, as well as the Charles, Mystic, and Neponset rivers all exceeded the EPA standards for phosphorus loading, even on their lowest days. This phosphorus overload can hurt the appearance and smell of the rivers, making them useless as recreational places, and in paces like the Charles River, recreation is of critical importance. In 2013 the Head of the Charles Regatta attracted around 9, 000 rowers, made $4.8 million in local and state taxes. Some local businesses and hotels depend on the nearly $47 million earned during the regatta weekend. Once phosphorus runoff gets into a body of water, it can be hard to get it out again. Phosphorus deposited 10 or even 20 years previous can still cause an algae bloom. Every day without action causes harm.

Fertilizer runoff is a primary source of this phosphorus. For this reason, Massachusetts passed a law that would limit the amount of phosphorus in lawn fertilizers. The decreased phosphorus load of these fertilizers could save the state of Massachusetts as much as $ 180 million per year in water treatment costs. The law imposes a fine for putting phosphorus on a non-agricultural area without first testing the nutrient balance of the underlying soil. Lawns that aren’t established yet are exempt. The law also regulates times of year in which the fertilizer can be applied, since during some times of year soil conditions make runoff more likely. In addition, fertilizer retailers must display phosphorus-rich fertilizers separately from non-phosphorus fertilizer and put up a sign explaining that the law prohibits the use of phosphorus fertilizer on non-tested lawns. This is an important regulation and should be pretty non-controversial. While fertilizer used for food could potentially have a reason for high phosphorus, since that phosphorus is meant to fuel plants that people eat, non-agricultural land does not need this kind of attention.

Not to mention that the fertilizer might not even help your lawn that much. Using a fertilizer with too much phosphorus can actually hurt your garden. This excess phosphorus can crowd out other more important soil nutrients, and can harm soil organisms that live symbiotically with garden plants, helping them grow with fewer nutrients.

The lawn laws enacted in August were a notable victory with a just as notable gap. As mentioned previously, there is a fine for non-compliance, but a monitoring system would be next to impossible to implement. The best thing citizens can do for this law now is to follow it voluntarily and to spread the word about the personal and statewide financial benefits this law produces.

Non-Massachusetts residents can also help their own states by voluntarily reducing fertilizer consumption. Get your soil tested to see what your soil actually needs before you load up on fertilizer. A simple test usually costs from $7 to $10 while a container of high phosphorus fertilizer which you might not need can cost as much as $13 or even $40 . UMass Amherst is one of many places that will test your soil. Here are some guidelines for reducing phosphorus runoff from your lawn, and here is a guide for reading fertilizer bags, so you know what you’re buying. Extra credit: ask your representatives to seek phosphorus regulations in your own state. Your local water sources, and maybe even your lawn, will thank you.