Friday, May 27, 2022

Greenfield Lake has been considered an ‘impaired’ body of water for 3 years

Despite frequent city cleanups, litter, pet waste and stormwater runoff contribute to the issues facing the Greenfield Lake ecosystem. (Port City Daily photo / JOHANNA FEREBEE)

WILMINGTON — Litter, pet feces, runoff, aging and potentially leaking septic tanks: Greenfield Lake is in trouble, has been in trouble, and the fault is widely shared.

At 250 acres, the public park, which contains the urban, blackwater impoundment, has been on North Carolina’s 303(d) list of impaired waters since 2014.

The city and non-profit volunteer organizations like the Cape Fear River Watch have gone to great lengths to inform and involve the public in this ongoing issue.

Regardless, researchers, volunteers, and city officials agree that the impaired state of Greenfield Lake is relatively unknown to the general citizenry.

An urban watershed

“It’s getting 2,500 acres of land draining runoff to it and all of the things that could be in the runoff,” said Jessica Butler, Stormwater Education Program Manager for the city.

“We’re all impacting it whether we realize it or not,” Butler said.

The 2,500-acre watershed includes densely populated, heavily paved residential and commercial land, where rainwater is not easily absorbed into the ground. Consequently, Greenfield Lake receives the brunt of the surrounding watershed’s runoff, which is often filled with litter, fecal coliform, sediment, fertilizers, and excess nutrients which ultimately degrade the overall health of the impaired ecosystem.

Harmful algal blooms and excess nutrients have been negatively impacting the overall health of the Greenfield Lake ecosystem for years. (Port City Daily photo / JOHANNA FEREBEE)

“One gram of pet waste has 23 million bacteria,” Butler said. “Think about the pets in that watershed.”

So far, aiding the public park has been a united effort. The burden of responsibility is shared by citizens and city officials alike.

“In terms of who can help solve, it, it’s everybody,” Butler said. “It’s the city, it’s businesses.”

In good faith

Since 2005, the city has taken direct steps to address the vitality of the lake. From stocking thousands of sterile grass carp and installing SolarBee water circulation systems to adding herbicides, lake improvement has remained a fluctuating endeavor.

Despite the city’s ongoing efforts, the lake’s chlorophyll concentrations tripled, even after the addition of the carp and circulation devices.

UNCW Professor Dr. Michael Mallin has produced decades of research on water quality and is the premier source of expertise on the health of Greenfield Lake according to city officials.

Harmful algal blooms and excess nutrients have been negatively impacting the overall health of the Greenfield Lake ecosystem for years. (Port City Daily photo / JOHANNA FEREBEE)
Harmful algal blooms and excess nutrients have been negatively impacting the overall health of the Greenfield Lake ecosystem for years. (Port City Daily photo / JOHANNA FEREBEE)

Mallin’s findings reveal that even the most well-intended rehabilitation efforts can have unintended consequences. His team has been working to identify which specific area within the watershed is contributing the highest quantity of harmful material.

They aim to identify and inform the city and area professionals which best management practices might be adopted in order to most effectively address the dire status of the park’s water.

The team’s findings will be presented this weekend at UNCW Center for Marine Science, during the North Carolina Lake Management Society’s conference on small lakes and dams.

Managing runoff 

Johnny Foster, president of Foster Lake & Pond Management, representing North Carolina Lake Management Society, sees the issues Greenfield Lake has been facing as complex.

Harmful algal blooms (fast growing algae), which can be toxic under certain conditions, as well as excess nuisance vegetation, had begun to impact human recreational involvement.

“It had gotten so bad out there where people couldn’t use the paddle boats and they couldn’t kayak or anything,” Foster said. On top of the harmful vegetation, litter has proven to be a cluttering issue with the lake as well.

“There’s a ridiculous amount of trash,” Foster said. “It’ll get cleaned up and just a few days later it looks bad again.”

As technology and awareness within city officials improved, so did stormwater management plans. Current codes and procedures take measures to minimize the amount of pollutants which flow downstream, however, much of the Greenfield Lake watershed was developed prior to these rules being in place.

“(We) can’t demolish homes and businesses to build the stormwater devices that would be required if the construction were new,” Foster said.

After decades of united efforts, area experts recognize that this is no easy fix.

“It’s a complicated problem,” Foster said. “There is no good answer.”


Johanna Ferebee can be reached at johanna@localvoicemedia.com or @j__ferebee on Twitter. Part two of this piece will become available early next week. 

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