COLORADO WQCD Letter - Boston Ave Bridge Replacement Letter 11-23-21.pdf

4300 Cherry Creek Drive S., Denver, CO 80246-1530 P 303-692-2000 www.colorado.gov/cdphe

Jared Polis, Governor | Jill Hunsaker Ryan, MPH, Executive Director

November 23, 2021

Rebecca Podkowka Environmental Resource Specialist U.S. Army Corps of Engineers 1616 Capitol Avenue Omaha, NE 68102 Rebecca.L.Podkowka@usace.army.mil

Re: Request for 401 Certification of Saint Vrain Creek Continuing Authorities Program Section 305 Flood

Risk Management Study

Dear Ms. Podkowka, The U.S. Army Corps of Engineers (“Corps”) has partnered with the City of Longmont (“City”) to identify and implement flood control projects along the Saint Vrain River. The projects will be designed to repair infrastructure damaged during flooding in September 2013 and to improve the river’s resilience to future flooding events. Collectively, these projects are referred to as the Saint Vrain Creek Continuing Authorities Program Section 305 Flood Risk Management Study (“Saint Vrain Project” or “Project”). After performing an alternatives analysis in accordance with the National Environmental Policy Act (“NEPA”) and section 404(b)(1) of the Clean Water Act, the Corps identified Alternative 7 as the preferred alternative for implementing the Saint Vrain Project. Alternative 7 comprises the following elements:

• Channel improvements: Widening and deepening the channel, constructing a “habitat channel” to accommodate low flow conditions, and installing retaining walls where necessary;

• Levee: Constructing an earthen berm-style levee approximately 900 feet long, five feet high, and 20 feet wide, installing a multi-use trail on top of the levee, and seeding the disturbed area after construction to improve stability;

• Grade control structure: Installing a grade control structure at the upstream end of the project approximately 245 feet long with a five-foot change in elevation; and

• Boston Avenue bridge replacement: Replacing an existing bridge to increase the flows it can accommodate, requiring the installation of four two-foot wide piers and three new bridge spans

In July 2020, the Corps finalized an Environmental Assessment for the Project. In October 2020, it issued a Finding of No Significant Impact.

The Project requires the discharge of dredged and fill material into waters of the United States. However, it does not require a Clean Water Act section 404 permit because the Corps is the project proponent, and the Corps “does not process and issue permits for its own activities.” 33 C.F.R. § 336.1(a). Nevertheless, federal regulations direct the Corps to “seek state water quality certification” when its own activities involve a discharge of dredged or fill material into waters of the United States. Id. § 336.1(a)(1). Consistent with these requirements, the Corps initiated discussions with the Colorado Department of Public Health and Environment’s Water Quality Control Division (“division”) to determine whether the Saint Vrain Project requires a Clean Water Act section 401 water quality certification (“401 certification”).

The division hereby notifies the Corps that the Saint Vrain Project does not require a 401 certification.

Section 25-8-302(1)(f), C.R.S., requires that the division review and certify, conditionally certify, or deny requests for 401 certification under the provisions of section 401 of the federal Clean Water Act. Section 401 requires that any applicant for a federal license or permit provide the federal licensing or permitting agency a 401 certification from the appropriate certifying authority. Similarly, Colorado’s 401 Certification Regulation applies to “federal license[s] or permit[s] for which water quality certification is required.” 5 C.C.R. 1002-82.3(A). Because the Saint Vrain Project does not require a federal license or permit, neither the federal Clean Water Act nor Colorado’s relevant statutes or regulations require that the division issue a 401 certification.

While the division need not issue a 401 certification, the construction activities, permanent channel modifications, and infrastructure components associated with the Saint Vrain Project have the potential to impact water quality. The division is particularly concerned about any potential for the Project to contribute to existing exceedances of water quality standards. The Project will directly impact one segment that is currently on Colorado’s 303(d) List of Impaired Waters, and construction activities will occur immediately upstream of a reach of the Saint Vrain River that is subject to a Total Maximum Daily Load (“TMDL”) (Table 1). Furthermore, Regulation #38 identifies the impacted segment as “reviewable.”

Reviewable waters are subject to Colorado’s antidegradation rule, which establishes more stringent requirements for regulated activities that may affect water quality. 5 C.C.R. § 1002-31.8.

Table 1. Saint Vrain River Segments (South Platte Basin) Impacted by the Saint Vrain Project.

Segment WBID Description Parameter (Use) Status

COSPSV03

Mainstem of St. Vrain Creek from Hygiene Road to the confluence with the South Platte River

E. coli (Recreation) 303(d) List

Ammonia (Aquatic Life) TMDL

In light of the Project’s potential impacts to water quality, the division requests that the Corps implement Best Management Practices (“BMPs”) capable of avoiding, minimizing, or mitigating water quality impacts both during and after Project construction. Project BMPs should address, but not be limited to: stormwater runoff, potential impacts associated with any increased recreation, potential impacts to aquatic life before vegetation reestablishes on cleared streambanks, and any potential sources of pollutants in the project area. For information on the division’s standard recommendations regarding BMPs, the Corps should consult Clean Water Policy 12: Colorado Best Management Practices. The policy is available on the division’s website: https://cdphe.colorado.gov/clean-water-policies.

In addition, the division encourages the Corps to collect water quality samples before, during, and after Project construction. Collecting water quality samples would allow the Corps to monitor the effectiveness of selected BMPs and adjust them as needed to ensure adequate water quality protection. The division recommends that the Corps submit a water quality sampling plan consistent with these objectives for the division’s review. The plan should include sampling locations, an estimated sampling schedule, and the constituents for which samples will be analyzed. Upon request, the division will assist the Corps in developing an appropriate sampling plan. If the Corps does collect samples, the division requests that it submit all sample results to assure the division that selected BMPs effectively control any Project-related water quality impacts.

Lastly, the division requests that the Corps submit final Project design documents to the division as they become available, including its final plans for BMP implementation and any required mitigation. The division also requests that the Corps notify the division of any major changes in project design. Major changes include changes in the location or quantities of material to be discharged and any other changes https://cdphe.colorado.gov/clean-water-policies that may result in water quality impacts not considered at the time of this letter. See 5 C.C.R. § 1002- 82.6(4).

The Corps should submit sampling plans, sample results, final Project design documents, and information about major changes in Project design via email to cdphe_wqcd_surfacewaterdata@state.co.us. The email should clearly identify that it is associated with the Saint Vrain Creek Continuing Authorities Program Section 305 Flood Risk Management Study and that the division’s 401 certification team is the intended recipient.

This letter does not dismiss the Corps from obtaining any other division permits that may be required for the Project. Furthermore, if the Project requires a federal license or permit in the future, it will also require a 401 certification. Please contact Trevor Klein at trevor.klein@state.co.us with any questions regarding this letter.

Sincerely, Trevor Klein Water Quality Assessor and 401 Certifications Specialist Watershed Section/Clean Water Program mailto:cdphe_wqcd_surfacewaterdata@state.co.us mailto:trevor.klein@state.co.us