Public Notice: Water Quality Certification for Cowlitz Tribal Gaming Authority Ilani Hotel Stormwater Pond Expansion Project

Publish Date


On July 28, 2022, EPA received a request from the Cowlitz Tribal Gaming Authority for a Clean Water Act Section 401 Water Quality Certification for the Ilani Hotel Stormwater Pond Expansion (Seattle District Corps of Engineer’s permit project number NWS-2022-0078).

Section 401(a)(1) of the Clean Water Act requires applicants for federal permits and licenses that may result in discharges into waters of the United States to obtain certification that the discharge will comply with applicable provisions of the Clean Water Act. Where no state agency or tribe has authority to give such certification, EPA is the certifying authority.

In this case, the Cowlitz Indian Tribe does not have the authority to provide Clean Water Act Section 401 certification. Therefore, EPA is making the certification decision for discharges that may result from the proposed project.

EPA is requesting comments on its Clean Water Act Section 401 water quality certification for the proposed project. As a certifying authority, EPA must decide whether to:

  1. Grant certification as proposed.
  2. Grant certification with 401 conditions.
  3. Deny certification.
  4. Waive certification.

Project Description


The proposed Ilani Hotel Stormwater Pond Expansion Project is located within Cowlitz Indian lands near Ridgefield, Washington, at latitude 45.853179, longitude -122.706438.


The project proposes to expand an existing stormwater pond to adequately accommodate and manage stormwater runoff from existing structures that had gone to the pond that have been displaced, as well as stormwater runoff resulting from the adjoining new hotel buildings and pavement.

Stormwater management for the Ilani Casino and the recently constructed adjoining hotel is currently provided by seven detention/wet basins located around the perimeter of that site. Stormwater management modeling showed that all ponds are currently near capacity with no additional storage available for runoff from the new hotel. Additional stormwater storage and treatment is required. One of the ponds has been displaced by the hotel construction.

Proposed Work and Impacts

The existing pond will be expanded by excavating 3,957 square feet (523 cubic yards) of an adjacent wetland with heavy equipment including excavators, bulldozers and graders. The construction will include:

  • Surveying the project area.
  • Clearing the area and installing erosion control measures.
  • Excavating the pond extension.
  • Constructing a new berm.
  • Installing new catch basin structure and outflow.
  • Access road construction.
  • Demolishing the old catch basin structure.
  • Removing the north pond berm.
  • In-pond and around-pond planting and seeding.

Over the course of this project, up to 507 cubic yards of native soil excavated on site will be placed in wetlands for the stormwater pond and berm construction.

Stormwater will be treated for water quality and discharged to a drainage channel at a highly moderated rate as per the required stormwater manual. The drainage channel flows directly into an unnamed tributary, which flows into the East Fork Lewis River.

Stormwater management will conform to the Department of Ecology Stormwater Management Manual for Western Washington, Best Management Practice T10.10 Wetpond design criteria.


The project proponent proposes to purchase 0.20 credits from the East Lewis River Mitigation Bank to compensate for unavoidable impacts to 0.20 acres of wetland within the same watershed.


The project construction work is proposed to occur between August and September 2022.

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