Protecting Public Health and the Environment.

DEQ seeks comment on draft certification of Hells Canyon Complex project

Friday, December 14, 2018

BOISE — The Idaho Department of Environmental Quality (DEQ) is seeking public comment on a draft water quality certification of the federal license issued by the Federal Energy Regulatory Commission (FERC) for the continued operation of Idaho Power Company’s (IPC’s) Hells Canyon Complex.

The Hells Canyon Complex is a three-dam complex that includes Brownlee, Oxbow, and Hells Canyon projects, reservoirs, and power plants on the Snake River.

Under Section 401 of the federal Clean Water Act, state certification of FERC licenses is required before hydropower operations may take place. IPC must receive water quality certifications of the Hells Canyon Complex project from Idaho and Oregon.

Idaho DEQ’s draft certification specifies the following conditions must be met to ensure compliance with water quality standards, state law, and the Snake River Hells Canyon Total Maximum Daily Load (SRHC-TMDL):

  • Implement the Snake River Stewardship Program to reduce temperature in the Snake River.
  • Implement the Brownlee operational component to reduce temperature in the Snake River when modeled temperatures are forecasted to exceed 16.5°C as a 7-day average maximum temperature in the complex outflow during the salmonid spawning period.
  • Implement the Riverside Operational Water Quality Improvement Plan to increase Brownlee Reservoir dissolved oxygen levels.
  • Implement the distributed aeration systems on the Brownlee powerhouse to meet dissolved oxygen criteria below Hells Canyon Dam.
  • Implement a destratification plan in the Oxbow Bypass to comply with dissolved oxygen water quality criteria.
  • Implement flow deflectors and preferential flow through the upper gates when spilling at the Brownlee Dam to comply with the total dissolved gas water quality criteria.
  • Monitor and report any harmful algae blooms in the complex.
  • Study and report annually on mercury and methylmercury fate and transport in the complex, and if necessary, develop and implement a methylmercury plan to address the complex’s role in methylmercury production.
  • Implement alternative measures should the primary implementation be inadequate in meeting water quality criteria.

Provided the above conditions are met, DEQ proposes to certify that the IPC application offers reasonable assurance that the discharges will comply with state water quality standards, state law, and the SRHC-TMDL.                                                

The draft certification and Idaho Power Company’s application are available for review at DEQ’s State Office in Boise and on DEQ’s website (download at right).

As part of the application process, IPC requested that DEQ waive or raise the salmonid spawning temperature standard by 0.3 °C above the 13.0 °C temperature standard for the portion of the Snake River below Hells Canyon Dam to the confluence with the Salmon River.  DEQ proposes to raise the maximum weekly maximum temperature criteria to 13.3 °C from October 23 through November 26, the initial portion of the salmonid spawning period. The 0.3 °C shift in temperature is an insignificant increase, and is consistent with the Oregon human use allowance and the SRHC-TMDL, and is fully protective of salmonid spawning.

This revised temperature standard only applies to the Hells Canyon Complex and IPC’s responsibility for reducing temperatures as proposed in IPC’s application for the 401 water quality certification.  It does not apply to any other source and is not a change in the criteria that otherwise apply to the Snake River. The IPC request to raise the temperature standard, DEQ’s response, and supporting material are available for review at DEQ’s State Office and on DEQ’s website (download at right).

Submit written comments on the draft certification and DEQ’s decision to grant IPC’s request to raise the temperature standard by February 12, 2019, at 5 p.m. MST on DEQ's website or by mail or email to:

Barry N. Burnell
DEQ State Office
Water Quality Division
1410 N. Hilton
Boise, ID 83706

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