Introduction
Missouri sits at the confluence of the nation’s two largest rivers—the Mississippi and the Missouri—making water quality management a critical priority for the state. The wastewater infrastructure landscape in Missouri is characterized by a dichotomy between massive metropolitan districts in St. Louis and Kansas City and a vast network of smaller municipal and rural lagoon systems. The Missouri Department of Natural Resources (MoDNR) oversees compliance for over 1,500 permitted wastewater facilities, ensuring the protection of the state’s 115,000 miles of streams.
Currently, the state is in a period of historic capital investment. Driven by federal consent decrees in the major metros and an influx of American Rescue Plan Act (ARPA) and IIJA funding for rural communities, the state’s engineering and construction sector is seeing activity levels exceed $2 billion annually. Key challenges include managing combined sewer overflows (CSOs), updating aging biosolids infrastructure, and meeting tightening nutrient removal standards to combat hypoxia in the Gulf of Mexico.
Recent Developments & Projects
The Missouri wastewater sector has been defined recently by aggressive implementation of long-term control plans (LTCPs) to address wet weather flows. The Metropolitan St. Louis Sewer District (MSD Project Clear) and KC Water (Smart Sewer) are both midway through multi-decade, multi-billion dollar consent decree programs.
Technologically, there is a significant shift toward energy neutrality and resource recovery. Kansas City is nearing completion on one of the largest Thermal Hydrolysis Process (THP) facilities in the Midwest, while St. Louis is investing heavily in fluid bed incineration and tunneling infrastructure. On the funding front, Governor Mike Parson’s administration has aggressively leveraged federal funds, allocating over $400 million in state ARPA grants specifically for water and wastewater infrastructure, triggering a wave of projects in mid-sized cities like Springfield, Columbia, and Jefferson City.
Top 20 Largest Wastewater Treatment Plants in Missouri
The following table ranks Missouri’s largest wastewater treatment facilities by design flow capacity (MGD). The list is dominated by the Metropolitan St. Louis Sewer District (MSD) and KC Water, which collectively serve nearly half the state’s population.
| Rank | Plant Name | City/Location | Design Capacity (MGD) | Operating Authority |
|---|---|---|---|---|
| 1 | Bissell Point WWTF | St. Louis | 150 (Peak 418) | MSD Project Clear |
| 2 | Lemay WWTF | St. Louis | 110 (Peak 240) | MSD Project Clear |
| 3 | Blue River WWTP | Kansas City | 105 (Peak 250) | KC Water |
| 4 | Missouri River WWTF | Maryland Heights | 38 (Peak 80) | MSD Project Clear |
| 5 | Birmingham WWTP | Kansas City | 32 (Peak 65) | KC Water |
| 6 | Southwest WWTP | Springfield | 42.5 | City of Springfield |
| 7 | Westside WWTP | Kansas City | 30 | KC Water |
| 8 | Coldwater Creek WWTF | Florissant | 25 | MSD Project Clear |
| 9 | Columbia Regional WWTP | Columbia | 20 | City of Columbia |
| 10 | Rock Creek WWTP | Independence | 16.5 | City of Independence |
| 11 | Lower Meramec WWTF | St. Louis Co. | 15 | MSD Project Clear |
| 12 | Water Protection Facility | St. Joseph | 27 (Permitted) | Missouri American Water |
| 13 | Shoal Creek WWTP | Joplin | 12.5 | City of Joplin |
| 14 | Northwest WWTP | Springfield | 10 | City of Springfield |
| 15 | Little Blue Valley | Independence | 10 | LBV Sewer District |
| 16 | Fenton WWTF | Fenton | 9.5 | MSD Project Clear |
| 17 | Grand Glaize WWTF | Valley Park | 9.0 | MSD Project Clear |
| 18 | Turkey Creek WWTP | Joplin | 8.5 | City of Joplin |
| 19 | Jefferson City Regional | Jefferson City | 8.5 | Missouri American Water |
| 20 | Main WWTP | Cape Girardeau | 8.0 | City of Cape Girardeau |
Profiles of the Top 5 Largest Facilities
1. Bissell Point Wastewater Treatment Facility
- Location: St. Louis, MO
- Design Capacity: 150 MGD (Average), 418 MGD (Peak Wet Weather)
- Population Served: ~680,000 residents
- Operating Authority: Metropolitan St. Louis Sewer District (MSD)
- Receiving Water: Mississippi River
Treatment Process: Bissell Point is the largest plant in the MSD system. It utilizes primary clarification followed by activated sludge secondary treatment. As a crucial component of MSD’s Project Clear, the facility handles massive combined sewer flows during storm events.
Infrastructure & Innovation: The plant recently commissioned new fluid bed incinerators to replace aging multiple-hearth units, significantly improving air quality emissions and solids handling efficiency. Energy recovery systems capture waste heat to reduce operating costs.
2. Lemay Wastewater Treatment Facility
- Location: St. Louis, MO (South County)
- Design Capacity: 110 MGD (Average), 240 MGD (Peak)
- Population Served: ~500,000 residents
- Operating Authority: MSD
- Receiving Water: Mississippi River
Treatment Process: Similar to Bissell Point, Lemay employs conventional activated sludge. It is the southern anchor of the St. Louis wastewater system.
Recent Upgrades: Lemay has been the site of extensive tunneling projects (Lemay Redundant Force Main) to eliminate sanitary sewer overflows. The plant utilizes biogas cogeneration to offset electrical demand.
3. Blue River Wastewater Treatment Plant
- Location: Kansas City, MO
- Design Capacity: 105 MGD (Average), 250 MGD (Peak)
- Population Served: ~400,000 residents
- Operating Authority: KC Water
- Receiving Water: Missouri River
Treatment Process: The workhorse of the Kansas City system, Blue River treats approximately 70% of the city’s wastewater. The facility uses step-feed activated sludge.
Notable Features: The plant is currently integrating a massive Thermal Hydrolysis Process (THP) facility, which will consolidate solids processing from other KC plants, produce high-quality Class A biosolids, and generate significant renewable natural gas (RNG).
4. Missouri River Wastewater Treatment Facility
- Location: Maryland Heights, MO
- Design Capacity: 38 MGD (Average)
- Operating Authority: MSD
- Receiving Water: Missouri River
Overview: Serving the rapidly growing western St. Louis County area, this plant features advanced secondary treatment. Recent capital improvements have focused on headworks reliability and odor control systems to accommodate suburban encroachment.
5. Birmingham Wastewater Treatment Plant
- Location: Kansas City, MO (Northland)
- Design Capacity: 32 MGD
- Operating Authority: KC Water
- Receiving Water: Missouri River
Overview: Serving the expansive “Northland” area of Kansas City, Birmingham utilizes oxidation towers and activated sludge. It is a key focus for future expansion as residential development continues north of the river.
Plants with Approved Budgets & Expansion Projects
A. Major Projects Under Construction (2024-2026)
Blue River Biosolids Facility (Kansas City) – $140 Million+
- Location: Kansas City, Jackson County
- Project Scope: Construction of a regional solids handling facility using Thermal Hydrolysis Process (THP) and anaerobic digestion.
- Funding Breakdown: WIFIA Loan (49%), Revenue Bonds (51%).
- Key Contractors: Black & Veatch (Design), Goodwin Brothers (Construction).
- Expected Completion: Late 2025.
- Drivers: The project eliminates the use of multiple hearth incinerators, ensuring compliance with Clean Air Act regulations and producing Class A Biosolids for land application.
Lower Meramec Tunnel (MSD Project Clear) – $180 Million
- Location: St. Louis County
- Project Scope: Construction of a 6.8-mile deep rock tunnel to eliminate 24 sanitary sewer overflows.
- Funding: MSD Revenue Bonds / SRF.
- Key Contractors: SAK Construction (Tunneling).
- Timeline: Construction ongoing, completion expected 2025.
- Expected Benefits: Prevents wastewater from entering the Meramec River during heavy rains; conveys flow to the Lower Meramec WWTF.
Springfield Northwest WWTP Expansion – $30 Million
- Location: Springfield, Greene County
- Project Scope: Capacity expansion and biological nutrient removal upgrades.
- Funding: Clean Water SRF.
- Status: Construction Phase.
- Drivers: Population growth in Greene County and stricter nutrient limits for the Sac River watershed.
B. Projects in Design/Planning Phase (2025-2027)
- Jefferson City Regional Water Reclamation Facility Upgrades:
- Estimated Budget: $45 Million.
- Scope: Headworks replacement and secondary treatment improvements.
- Status: Design phase.
- City of Columbia Integrated Management Plan Projects:
- Estimated Budget: $25 Million (Phase 1).
- Scope: Sewer rehabilitation and plant hydraulic improvements to address inflow and infiltration (I&I).
- City of O’Fallon WWTP Expansion:
- Estimated Budget: $18 Million.
- Scope: Expansion to accommodate rapid suburban housing growth.
Summary Statistics
- Total Active Capital Investment: ~$1.8 Billion (Statewide)
- Number of Major Active Projects: 35+ facilities
- Primary Project Drivers: Consent Decrees (60%), Aging Infrastructure (25%), Growth/Capacity (15%)
- Funding Sources: Revenue Bonds (Major Metros), SRF Loans (Mid-sized cities), ARPA/State Grants (Rural).
Regulatory & Compliance Landscape
The Missouri Department of Natural Resources (MoDNR) administers the NPDES program. The defining regulatory feature in Missouri is the focus on wet weather management. Both St. Louis and Kansas City are operating under federal consent decrees requiring the elimination of CSOs and SSOs, driving the bulk of engineering spend.
Additionally, Missouri is increasing its focus on nutrient reduction. The state’s Nutrient Loss Reduction Strategy aims to reduce nitrogen and phosphorus loading to the Mississippi River Basin. Plants are increasingly facing tighter permit limits for Total Phosphorus (TP) and Total Nitrogen (TN), necessitating upgrades to Biological Nutrient Removal (BNR) processes.
Technology Trends in Missouri
- Thermal Hydrolysis (THP): KC Water’s adoption of THP marks a regional shift toward advanced sludge treatment to reduce volume and create Class A biosolids.
- Tunneling: Deep rock tunneling is the primary technology being used in St. Louis for storage and conveyance of overflow volumes.
- UV Disinfection: A rapid transition away from chlorine gas to UV disinfection is occurring across mid-sized municipal plants to improve safety and reduce chemical byproducts.
- Real-Time Control (RTC): “Smart Sewer” initiatives are deploying sensor networks and AI-driven gate controls to maximize in-system storage before building new concrete tanks.
Resources for Engineers & Operators
- Missouri Water Environment Association (MWEA) – The state affiliate of WEF.
- Missouri Department of Natural Resources – Water Protection Program – Permitting and compliance data.
- Missouri State Revolving Fund (SRF) – Funding information for infrastructure projects.
- Missouri Public Utility Alliance (MPUA) – Resource for municipal utilities.
Frequently Asked Questions
- What is the largest wastewater treatment plant in Missouri?
- The Bissell Point Wastewater Treatment Facility in St. Louis is the largest, with a peak wet weather design capacity of over 400 MGD.
- What are the major drivers for wastewater projects in Missouri?
- The primary drivers are federal consent decrees (CSO/SSO reduction) in Kansas City and St. Louis, followed by nutrient removal requirements and aging infrastructure replacement.
- How much is being invested in Missouri wastewater infrastructure?
- Between MSD Project Clear, KC Smart Sewer, and state SRF projects, annual capital investment currently exceeds $1.5 billion.
- What funding is available for Missouri treatment plants?
- Funding includes the Clean Water State Revolving Fund (SRF), WIFIA loans (for large projects), and recent ARPA/IIJA allocations administered by MoDNR.
- Are there nutrient removal requirements in Missouri?
- Yes, MoDNR is progressively implementing nutrient criteria for lakes and streams, forcing many mechanical plants to upgrade to biological nutrient removal (BNR) technologies.