Idaho’s Response
Through ISDA’s Early Detection Monitoring Program, quagga mussel larvae was confirmed in the Twin Falls area of the Snake River on September 18th. The discovery of quagga mussel veligers in the Snake River marked the first time a rapid response plan had been put into action for quagga mussels in Idaho.
The response to the quagga mussel detection in the Snake River quickly became a major priority to the ISDA, Governor Little’s Office, as well as several federal, state and local agencies. The quagga mussel response is an ongoing effort for State of Idaho to protect our waters and way of life from a potentially devastating infestation.
Containment measures
September 19 - ISDA begins decontaminating all watercraft and conveyances that had been in the Centennial Park area of the Snake River in the last 30 days.
September 19 - ISDA closes off public access to the Snake River between Niagara Springs and Twin Falls.
October 19 - ISDA reopens the Snake River from the highwater mark from Highway 46 Bridge upstream to and including the partial bridge structure in the Snake River at the bottom of Yingst Grade (known as “the Broken Bridge,” “Yingst Grade Bridge,” or “the Old Interstate Bridge”).
December 18 - ISDA reopens water access between Broken Bridge (Yingst Grade) and Pillar Falls. Mandatory decontamination is in place prior and post entry.
Today - Water access from Pillar Falls to Twin Falls Dam remains closed.
Public access closure includes, but is not limited to prohibiting any persons, watercraft, pets, decoys, and fishing tackle from accessing the water. Accessing the water in the ISDA closed area of the Snake River is a violation of Idaho Code (IDAPA 02.06.09).
delimiting surveys
To better understand the extent of the physical range of impacted area, ISDA staff surveyed the water in the Mid-Snake River area for quagga mussel larvae. ISDA staff and partners surveyed at a rapid pace to map out any other presence of quagga mussel larvae or adults in the area.
Samples from the Snake River were then sent to a lab to identify any mussel larvae in the samples through microscopy. Any samples identified as possible quagga mussel were then transferred to another lab for PCR (genetic) confirmation.
ISDA divers identified an adult mussel that was located near Shoshone Falls, which was consistent with the veliger sample data. Sample results indicated there was a population of quagga mussel larvae specifically in the Shoshone Falls area. No larvae were confirmed upriver of the Twin Falls Dam or downriver of Centennial Park. Sampling occurred in surrounding lakes and reservoirs, upstream from Milner Dam to American Falls, and downstream to the Idaho Power Dam Complex at Hagerman.
The survey data was used in ISDA’s treatment planning.
control strategy
Since the discovery of quagga mussel larvae in the Snake River, ISDA has been dedicated to an aggressive approach for treatment to protect Idaho’s waters from these mussels.
ISDA utilized a comprehensive treatment strategy, which was developed with the review and assistance of many agencies and groups including; Governor Little’s Office, Idaho Department of Fish and Game, Idaho Office of Species Conservation, Idaho Department of Environmental Quality, Idaho Department of Water Resources, Idaho Department of Parks and Recreation, Idaho Department of Lands, Idaho Power, canal companies, Idaho Water Users Association, U.S. Environmental Protection Agency, U.S. Fish and Wildlife Service, U.S. Geological Survey, U.S. Army Corps of Engineers, U.S. Bureau of Land Management, and U.S. Bureau of Reclamation.
We appreciate the continued assistance and cooperation of the Twin Falls and Jerome County Commissioners, the City of Twin Falls, and the Idaho Office of Emergency Management.
Notifications
The ISDA along with several partners worked to inform residents of the Magic Valley and all Idahoans of the quagga mussel response efforts. Communication to the public was a crucial aspect of the rapid response plan. The following communication methods were employed.