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Quagga Mussel Infestation Greater Than Feared At Lake Powell In Glen Canyon NRA

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Dropping water levels at Lake Powell in Glen Canyon National Recreation Area have revealed a much greater infestation of quagga mussels in the reservoir than previously thought.

In a release Tuesday, officials for the National Park Service said that since this time last year, the water levels at Lake Powell have dropped, exposing shorelines that were previously underwater, and revealing the non-native mussel infestation.

"Thousands of adult quagga mussels have been found in various locations, such as canyon walls, Glen Canyon Dam, boats, and other underwater structures," noted NRA spokeswoman Denise Shultz. "The majority of mussels found are isolated adults, with additional groupings of small clusters. One adult mussel was found on the south canyon wall of Bullfrog Bay."

Last summer, following an underwater inspection of the NRA's two major marinas on the lower end of Lake Powell, officials were optimistic the huge reservoir could still be kept free of a major infestation.

A total of 36 divers and 73 support staff participated in the project, which had two main goals: assess the extent of quagga mussels in lower Lake Powell, and remove all existing mussels. The outcome could be described as a classic case of both good news and bad.

On day one, June 10, divers found and removed 138 mussels at Antelope Point Marina. The second day yielded 63 mussels at Wahwep Marina, with an additional 22 of the creatures on June 12. On the final day, a dozen additional quagga were removed. The grand total for four days: 235 mussels.

According to a park spokesperson, divers located mussels on moored boats, docks, and breakwaters dispersed throughout both marinas, but did not find any large colonies of mussels. The mussels varied from the size of a pea to the size of a quarter, which suggests a range of different ages.

Following the latest news, NRA officials said boat inspections and decontamination of high risk boats are still required for incoming vessels at Glen Canyon. Continued mussel education and prevention activities, including boat inspections, are aimed at minimizing the chances that mussels will colonize other areas of the lake. It may also prevent the introduction of other aquatic invasive species.

It is crucial to keep the mussels from moving from Lake Powell to other lakes and rivers. When leaving Lake Powell, all watercraft are required by Utah and Arizona state law to be decontaminated (Clean, Drain, and Dry) before being moved to another water body. Regulations vary depending on the state, so all boaters should review the regulations of any states they will enter with their watercraft after being at Lake Powell, including Arizona and Utah.

To help stop the spread of mussels:

You must clean and drain your boat before you leave the vicinity of the lake.
You must dry your boat the required amount of time before moving it to another body of water.
OR you can have your boat professionally decontaminated.
“Park staff, partners, and the public have worked hard to keep Lake Powell mussel free for the last ten years,” said Superintendent Todd Brindle. “It’s very disappointing that mussels are in the lake, but most visitors will not notice them. The important thing now is to keep them from being transported to other lakes and rivers.”

A planning effort is currently underway to develop a Quagga/Zebra Mussel Management Plan (QZMP) to help the National Park Service decide what tools are appropriate to support the ongoing management of invasive mussels in Glen Canyon now that quagga mussels are present in Lake Powell. The QZMP will consider changes to the existing prevention and monitoring efforts, and will include analysis of potential control, containment, and other park management actions. 

 

Comments








And back to the original subject of this story - and the first two comments that started this discussion.

I doubt that many would dispute the assertion that quagga and their relatives the zebra mussles have already caused enormous economic damage, and those costs are likely to grow. It's too bad efforts to keep them out of Lake Powell seem to have failed.

The possibility of a biological control for those pests is an intriguing idea, but as others have pointed out, such efforts have been known to backfire. As a result, this possible "solution" to the quagga problem needs to be approached with considerable caution.


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