Contractor: RPB Fish Kill Needed For Weed Control

Dead fish in a canal brought a complaint to the March 20 meeting of the Royal Palm Beach Village Council.

Ronald Blicksilver of Van Gogh Way was upset that an aquatic weed treatment behind his home had led to a fish kill.

Blicksilver, a volunteer with the village’s marine unit involved with water safety and environmental issues in the canals, said fish had died in his canal after the village’s aquatic weed control contractor, Clarke Aquatics, had sprayed there.

This resulted in dead fish along the bank and vultures swooping in to consume the remains.

“I was horrified last Saturday to see a major fish kill behind my home, and that’s what I want to bring to your attention,” Blicksilver told council members. “Many people here know about it, so I’m not going to harp on it. I’m just going to ask that we see that this does not happen again.”

Blicksilver added that he had attended meetings last summer when residents complained about weeds choking the canals, and Clarke representatives outlined a comprehensive approach to weed control.

“They showed us these beautiful images from his ‘fish finder on steroids,’” Blicksilver said. “He cleaned the bottom of our canal dead. There’s nothing there anymore. The hardest thing for me to watch was this poor bass in shallow water trying to breathe, and a vulture waiting for him. Please, could we see that this does not happen again?”

According to a report to Royal Palm Beach Utilities Director Paul Webster from Clarke Water Resource Manager Dr. Brett Bultemeier, two chemicals were applied in the area at half the maximum allowable rate.

“We did not treat entire canals or the entire system, but targeted our treatment to the most affected areas,” he wrote.

The fish kill was most likely caused by the chemical hydrothol 191, Bultemeier explained. “We can surmise this because the fish were of one or two species, relatively small, and it occurred very rapidly after the treatment,” he wrote. “It is possible that a decrease in dissolved oxygen could have also contributed, but chemical toxicity is the most likely cause. It is known that this chemical poses potential risk to fish, but these types of treatment are allowed by the label.”

This outcome is not unexpected given the chemical and dosage applied, and is in line with what would be expected, he added.

“Although avoiding harm to fish is the desired outcome of all treatment activities, in this case it was unavoidable,” Bultemeier wrote. “The plants that are being targeted require the use of hydrothol 191, which carries a risk of fish toxicity, but to leave the plants uncontrolled poses an even larger risk. If no management actions are taken, there is an increased risk of fish kill due to dissolved oxygen depletion, and at a much larger and more intensive scale.”

Bultemeier termed the recent fish kill as “limited,” involving a limited number of fish, a limited number of species and in a limited area.

“A widespread dissolved-oxygen crash would be much more severe,” he noted. “The goal of the current management is to minimize the risk and only accept the risk when it is necessary to avoid a worse situation.”

The treatments were targeting three or four different exotic plant species, trying to prevent them from establishing further in the village’s canal system.

“Some of these exotic species are difficult to control, thus we used a combination of chemicals,” Bultemeier wrote. “If we don’t target these plants now, they can completely fill in the canal system, which creates its own set of problems.”

He added that the timing of the treatment was ideal both for controlling the plant appropriately and also in limiting damage to the fish.

“This is early enough in the year that the fish haven’t begun to spawn, they are not established in thick beds of weeds, and we aren’t putting young fry at risk,” Bultemeier explained. “Every step was taken to reduce the risk of fish toxicity, but risk can never be entirely removed. The damage suffered now reduces the greater potential later, and begins to ensure we don’t run this risk again.”

In other canal-related business, the council gave approval for the mayor to execute a special permit with the Indian Trail Improvement District regarding aquatic vegetation and weed control services for portions of the M-1 Canal located within the village.

Royal Palm Beach and ITID both contract with Clarke for aquatic weed control, but ITID has legal control of the M-1 Canal, and the village and ITID had not been able to coordinate a comprehensive weed control plan for the canal.

“It looks as though using that long, persistent approach to dealing with this issue has paid off,” Councilman Jeff Hmara said. “I don’t want to be overly optimistic, but I think this is a major step in the right direction.”

Webster credited Village Attorney Jennifer Ashton for conducting successful negotiations with ITID.

“This permit will allow us to be lead on the contracting of aquatic vegetation within the M-1 Canal,” Webster said. “We will do an addendum to our agreement with our contractor. What this provides for is uniformity on how the aquatic weeds in the entire Royal Palm Beach system will be managed.”