This algal bloom, which grew in South Portland’s Mill Cove in August 2016, was caused by too much nitrogen in the water, according to the Friends of Casco Bay. Contributed

SOUTH PORTLAND — Nine months after a special committee began looking to limit or ban fertilizers, the city’s sustainability coordinator said setting new rules is still “a work in progress.”

The delay comes as the city, which has five waterways listed as impaired urban streams, has also seen new algal growth.

“There’s still a lot to be decided,” Julie Rosenbach said, including whether a seasonal ban should be instituted, what to do about playing fields, whether to place limits on the maximum amounts to be used and enforcement.

Fertilizer is problematic because nitrogen is a key ingredient in all brands. Too much is harmful to marine water quality and sea life, numerous scientific studies have shown.

A thick carpet of algae smothered these juvenile clams in South Portland’s Mill Cove in August 2016. Contributed

Locally, fertilizers are already causing a “dramatic uptick” in nuisance and toxic algal blooms off the coast of Maine, according to Cathy Ramsdell, executive director of the Friends of Casco Bay and member of the city’s Fertilizer Working Group.

Another committee member, Jessie O’Brien, who chairs Maine’s Landscape and Nursery Association’s governmental affairs committee, said: “Landscape professionals care about the environment and any product use that’s off-target is both wasteful and harmful … a healthy green infrastructure is also important to the health of Casco Bay, so the more we can talk about (ways of) beefing up soil health the better.”


Both Rosenbach and Ramsdell said new rules are needed because education and outreach haven’t been enough.

“Outreach alone doesn’t quite work,” Rosenbach said, “but setting a standard for use has a much great impact.”

While limiting or banning fertilizers is still a relatively new discussion in Maine, more than 90 communities, mostly on the Gulf Coast of Florida, have adopted bans on using fertilizer from June 1 to Sept. 30, according to Rosenbach.

While little data exists on the effectiveness, media in Florida have reported a reduction in the number and size of algal blooms.

In Maine, Ramsdell said many eyes are on South Portland to see what the working group comes up with.

“What gets done at the local level, if it works, really matters,” she said, and may inspire statewide legislation.


South Portland’s five impaired urban streams – which means the water quality is particularly bad – include Long Creek and Trout Brook, which both flow into Casco Bay.

Ramsdell said “it’s very hard to measure how much nitrogen is in the water at any given time,” because it’s influenced by many factors, including rainfall.

She said algal blooms caused by excess nitrogen can be “crippling” to a body of water.

“(W) e’re now seeing algae in Maine that we’ve never seen before and it’s decimating clam flats,” which resulted in the closure of large areas of flats in Brunswick this past August.

Ramsdell added, “we have also definitely seen instances of new, bright green algal growth that when we trace it upstream we often find new development or a newly established lawn.”

The problem, according to Ramsdell, is that critical sea life is killed off when algal blooms decompose, which adds an excess of carbon dioxide to the water.

She said Maine has not yet seen the kind of dead zones being created elsewhere in the world – including one the size of New Jersey at the mouth of the Mississippi River – but every summer “we are now seeing mini dead zones” at a very localized level.

Those include a severe algal bloom in Mill Cove in August 2016 and one in Pleasantdale Cove this past summer.

Rosenbach said while the South Portland committee hasn’t yet reached an agreement on how to do it, any new rules will be specifically designed to “curtail misuse and overuse” of fertilizer.

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