Purpose of Wastewater Project
The current wastewater treatment facility (WWTF) for the City of Chiloquin (City) is located near the center of the City, south of Chocktoot Street, and east of the Williamson River. Most of Chiloquin’s existing facilities and equipment are approximately 40 years old, indicating they the nearing or exceeding the end of their design life. The WWTF consists of a contact-stabilization package treatment plant that combines an activated-sludge process in a single unit. The package treatment plant contains first-stage aeration, clarification, second-stage aeration, and an aerobic digester. In addition to the package treatment plant, the WWTF contains sludge drying beds, a chlorine contact basin, and a dechlorination system.
A thorough evaluation of the City’s WWTF was conducted. A Wastewater Facilities Plan (WWFP) was prepared for the City by Adkins Consulting Engineering, LLP, in conjunction with Anderson, Perry and Associates, LLC, concluding that the system requires replacements and major upgrades, regardless of whether any growth occurs in the Chiloquin service area.
Several factors indicate an upgrade is needed:
- New Limits – The existing treatment facility was not designed to remove phosphorus.
- Preliminary Treatment – A new headworks screening system is needed.
- Age – Many of the existing facilities were constructed as part of the 1976 wastewater system improvements. This makes the equipment approximately 40 years old and suggests the equipment is nearing the end of its design life and needs repair or maintenance.
- Redundancy – The existing facility will not allow the main treatment processes to be taken offline for maintenance. For this reason, the facility requires repairs and is underperforming due to the poor condition of the air diffusers and related components.
Project Update - March 2026
The City of Chiloquin has reached a major milestone in the effort to replace its aging wastewater treatment facility. We are pleased to share that the City has secured critical state funding through the Oregon State Legislature, closing the remaining funding gap for this essential infrastructure project.
This funding brings together multiple sources, including prior investments from the Indian Health Services and Business Oregon, and now the addition of state lottery bond funding. With these combined resources, the City is now positioned to move forward with the construction of a modern wastewater treatment system that will serve our community for decades to come.
The new facility will replace outdated infrastructure that is increasingly difficult to maintain and no longer meets current regulatory standards. The upgraded system will improve reliability, protect public health, and better safeguard local water quality. It also represents a long-term investment in Chiloquin’s future, supporting growth, housing development, and overall community resilience.
While the state funding is a significant step forward, the City is continuing to coordinate closely with funding partners and regulatory agencies to finalize timelines and next steps. Construction is anticipated to begin as early as this summer, pending final approvals and contracting.
As we celebrate Chiloquin’s 100th year, this project reflects both how far we have come and our commitment to building a strong foundation for the next century.
Project Update - January 2026
Staff and council members will be attending Water Day at the Capitol in Salem to meet with state representatives and share Chiloquin’s story. During these conversations, the city will highlight the urgent need to close the remaining funding gap for the City’s new wastewater treatment plant, a critical project needed to meet safety, compliance, and long-term community needs. This event gives Chiloquin the opportunity to speak directly with decision-makers and advocate for the resources needed to protect public health and support the City’s future. Currently, the remaining funding gap is $4.3 million out of the projected $8 million cost for the project.
Project Update - May 2025
The city has received a $2.5 million grant from the Indian Health Services through the EPA Clean Water Act Indian Set-Aside funds to help with the new wastewater facility project. The city is currently working to secure the remaining funding required for the project.
Project Update - August 2024
During the last council meeting, the council approved authorizing financial assistance from the Oregon Business Development Department (OBDD) for a $750,00 grant and a $910,000 loan for the new Wastewater Treatment Facility Project. To complete this project, the city plans to apply for a CDBG grant from Business Oregon in September and an additional grant from the Department of Environmental Quality (DEQ) to secure the final funding needed.
Project Update - February 2024
The wastewater project had been on hold pending a review by Oregon’s Land Use Board of Appeals (LUBA). It was recently dismissed by LUBA, a decision upheld by the Court of Appeals for the State of Oregon. The City will now be able to move forward on this project.
Project Update - 2021
In 2021, Klamath County approved the project, but a land-use appeal is currently pending with the Oregon Land Use Board of Appeals (LUBA). The City plans to apply for a Community Development Block Grant (CDBG) in the spring of 2022. If the City is successful in securing the CDBG grant and in the LUBA appeal process, construction would start in the summer of 2022.
Project Background
The City of Chiloquin owns and operates a conventional gravity wastewater collection system with lift stations near the wastewater treatment facility (WWTF) and a contact stabilization package treatment plant that provides secondary treatment of the wastewater. Currently, the City’s wastewater system serves approximately 735 residents and commercial establishments. The wastewater collection and treatment system operates under the authority of a National Pollutant Discharge Elimination System (NPDES) Permit issued by the Oregon Department of Environmental Quality (DEQ). The Permit was renewed in 2016. The NPDES Permit authorizes the City to construct, modify, and operate the facilities and discharge disinfected secondary treated effluent year-round to the Williamson River.
On July 9, 2003, the City was issued a Notice of Noncompliance (NON), ERB-03-10472, for failing to meet total suspended solids (TSS) removal efficiencies and for exceeding weekly average effluent TSS concentration limits. On April 16, 2004, the City was issued another NON (ERB-2004-11513) for failing to meet TSS removal efficiencies. Also, warning and pre-enforcement letters were issued on July 22, 2005, and February 16, 2007, respectively, notifying the City of permit violations related to TSS removals. To address the compliance matter and provide the City with a scheduled time frame for implementing corrective measures and improvements to the facilities, the City was issued a Mutual Agreement and Order (MAO) Number WQ/M-ER_06-245 on February 15, 2007.
Current collection system
The City’s collection system comprises approximately 30,000 linear feet (LF) of gravity sewer mains, 1,675 LF of pressure sewer mains, and four lift stations (Eastside, Westside, High School, and Baker Street). A private pump station serves approximately seven lots along the west side of the Williamson River, north of Chocktoot Street and east of Lalo Street. The size of piping in the collection system ranges from 4 to 12 inches in diameter, with the majority being 8 inches in diameter. The original collection system was installed before the 1950s and included the Eastside lift station. In 1961, improvements were made to the wastewater system that included new sewer main lines, and the Westside lift station was constructed to serve the area of the City west of the Williamson River. Significant wastewater collection system improvements were carried out in 1975 to reduce infiltration/inflow (I/I). Work included raising and sealing manholes, sealing pipe joints, and replacing portions of the sewer main line. In 1981, the Baker Street lift station was constructed to serve an area north of the WWTF, east of the Williamson River, and west of the Southern Pacific Railroad tracks. In the 2011 Wastewater Facility Improvements - Phase 1 project, an influent flow meter was added, additional sludge drying beds were built, and a dechlorination system was implemented.
Facility Upgrade Alternatives
The following three treatment process alternatives were developed and evaluated to provide a reliable facility that offers biological treatment and meets the effluent quality requirements:
- Treatment Process Alternative No. 1 – Membrane Bioreactor (MBR) Package Plant
- Treatment Process Alternative No. 2 – Sequencing Batch Reactor (SBR) Package Plant
- Treatment Process Alternative No. 3 – Construct New Lagoon Treatment, Storage, and Effluent Reuse Facility
Each of the alternatives would be designed to meet expected loads through the year 2038 for a projected population of 770 residents. The other options had to be operator-friendly, energy-efficient, and meet Class II reliability criterion, meaning that the facility could operate with the most significant single component out of service. The effluent from all alternatives must also meet the Oregon Department of Environmental Quality (DEQ) criteria for secondary treatment.
Of the three viable alternatives that were evaluated, Treatment Process Alternative No. 3 – Construct New Lagoon Treatment, Storage, and Effluent Reuse Facility was selected by the City. This selected improvement option has the lowest Operation, Maintenance, and Repair (OM&R) costs and, as a result, will be more cost-effective for the city, even given the high upfront costs. The Lagoon Storage and Effluent Reuse Facility will consist of a screening facility, pump station, lagoon, irrigation pump, solid-set irrigation, and an irrigation field.
With this alternative, the existing WWTF would be decommissioned, and a new or modified pumping system and pipeline to the new non-discharging facultative lagoon system would be constructed to treat effluent and store the reclaimed water for reuse as irrigation. The new WWTF would consist of a new two-cell lagoon system, a chlorine disinfection system, and an irrigation area. The first cell would be approximately 7 acres and used for treatment, while the second cell would be approximately 10 acres and used for storage. The total irrigation area for native vegetation would be approximately 41 acres.
Today, lagoon/irrigation style WWTFs are widely used across Klamath County and eastern Oregon, including Merrill, Malin, Bonanza, Bly, and Crescent.
New Lagoon Treatment, Storage, and Effluent Reuse Facility
The proposed Lagoon Storage and Effluent Reuse facility must be adequately monitored and maintained to protect groundwater. The storage lagoons will be lined to eliminate waste-to-soil interactions and protect groundwater. The irrigation will be applied to high water intake crops at agronomic rates to eliminate excessive groundwater seepage. Therefore, the groundwater will not be affected by the use or construction of this system.
Equipment
The Lagoon Storage and Effluent Reuse facilities will include pumps, valves, storage lagoons, a field, and a solid-set irrigation system. It is also equipped with a screening facility to remove rags, plastics, and other non-biodegradable materials before the effluent is pumped through the pipeline, a feature missing from the City’s current WWTF. The existing WWTF will be decommissioned, discontinuing the discharge of effluent into the Williamson River. The existing lift station will be used to pump effluent to the screening facility, after which it will the pumped through a 6-inch pipeline to the lagoon storage.
Lagoons
The lagoons will be facultative, meaning they consist of 3 distinct layers (aerobic, facultative, and anaerobic). The aerobic top layer of the lagoon requires both sunlight and oxygen to function correctly. It treats the wastewater by converting it into ammonia, carbon dioxide, and phosphates, which are absorbed by algae in the lagoons. The bottom layer of the lagoon contains a layer of sludge, which is digested by the anaerobic bacteria, helping minimize sludge accumulation in the ponds. The intermediate facultative layer contains both aerobic and anaerobic bacteria. The Lagoon will have a liner to eliminate contamination into the groundwater.
Disinfection
After treatment in the storage lagoons, the wastewater will flow through a chlorine-disinfection pipe to the irrigation pump. This final disinfection will eliminate any viruses and bacteria that may have survived the treatment lagoons.
Irrigation
After chlorine contact, the reclaimed water is pumped to a 41-acre area for irrigating native vegetation. Irrigation schedules should be monitored closely to minimize excess irrigation water.
