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DEQ seeks comment on draft 401 water quality certification for Twin Lakes channel dredging project

Accepting comments from April 20, 2022, through May 11, 2022.

The Idaho Department of Environmental Quality (DEQ) seeks comment on draft 401 water quality certification for Twin Lakes channel dredging project.

The applicant proposes to suction dredge the channel between Upper and Lower Twin Lakes to remove sediment, phosphorus, and organic material. In fall 2022, approximately 8,615 cubic yards of sediment and organic material will be suction dredged and pumped 2,000 feet via floating pipe to a treatment system and de-watering site at the Idaho Department of Fish and Game boat launch. The dredging footprint will be an “L-shape”; 50 feet wide by 1,800 feet long (west to east; southern-most end of the channel between Upper and Lower Twin Lakes) and 50 feet wide by 520 feet long (south to north; connecting the main channel to the boat launch). Dredging will remove the uppermost 2 feet of organic material and sediment from the channel floor.

Based upon its review of the certification request and supporting documents, received on March 17, 2022, DEQ certifies that if the permittee complies with the terms and conditions imposed by the permit and the conditions set forth in this water quality certification, then there is reasonable assurance the activity will comply with water quality requirements, including applicable requirements of Sections 301, 302, 303, 306, and 307 of the Clean Water Act, the Idaho Water Quality Standards (WQS), IDAPA 58.01.02, and other appropriate water quality requirements of state law.

The draft certification is available for public review at DEQ’s State Office (1410 N Hilton St) and on DEQ’s website. Written comments will be accepted through May 11, 2022 at 5 p.m. MDT. Submit comments electronically on DEQ’s website or by mail or email to:


Chantilly Higbee
Compliance Officer
Chantilly.Higbee@deq.idaho.gov

Related Documents

Draft certification

Public Comment Form

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