Snake River Quagga Mussel Treatment

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 several federal, state and local agencies and stakeholders.

the product

Natrix - Natrix is a copper-based product that is labeled and approved by EPA for these kinds of aquatic applications. Similar copper-based products are used in Idaho and other states for mussel, fish, algae, and plant control.

The product was applied at a rate that will eradicate mussels but is below the drinking water standard for humans.

treatment application

The ten day treatment began October 3 and concluded October 13, using a comprehensive treatment plan. The treatment application occurred across a sixteen-mile section – less than one percent – of the Snake River and is intended to eradicate quagga mussels at all life stages.

The product was slowly metered into the water to achieve 1 ppm and was maintained at the level by close monitoring by ISDA staff. The contracted applicator, the manufacturer, and ISDA staff extensively monitored the application 24 hours a day. 

The treatment went as planned in achieving target application rates at the 1 ppm of the product. The product diffused as we anticipated, not seeing any measurable copper levels or impact at the 16-mile downstream point. The application was completed October 13th and copper levels in the area were back to the normal baseline within a couple weeks post treatment. 

Treatment impacts

The adult mussel that was identified in the river pre-treatment experienced mortality within 48 hours of the first treatment block. Although initial veliger sample results indicated the treatment impacted larvae and adult populations, it is premature to conclude complete eradication at this stage. Quagga mussels stop reproducing once the water is below 14 degrees Celsius. Sampling will begin again in the spring once water temperatures reach 14 degrees Celsius. These samples will be an ongoing effort to determine the success of the treatment.