Working Holistically to Solve Mozingo Lake’s Water Quality Issues

The City of Maryville is undertaking a comprehensive, multiyear initiative to resolve longstanding water quality challenges in Mozingo Lake and modernize its drinking water system.  

To address these interconnected issues, the City partnered with HDR to lead a holistic One Water approach to examine its entire drinking water system from the 13,000-acre watershed to the treatment plant and corresponding distribution system. We began by conducting a thorough evaluation of raw water conditions, treatment processes, plant limitations, regulatory constraints, and the economic realities facing a service area of approximately 30,000 residents. This systemwide analysis highlighted the need for both immediate interventions and a comprehensive long-term strategy that could be implemented without burdening ratepayers or compromising service reliability.

We guided the City through rapid, cost-effective interim measures to stabilize water quality while long-term planning progressed. These actions included enhanced monitoring, implementation of a seasonal algaecide program and the creative repurposing of a decommissioned 1958 clearwell into a temporary granular activated carbon (GAC) adsorber. This upcycled GAC system provides a timely and affordable method for removing taste and odor compounds, preventing additional community dissatisfaction while extending the life of existing infrastructure.  

Concurrently, we advanced the City’s long-term solution: a new, approximately $50 million water treatment plant that will be the first in Missouri to use ozone and biological activated filtration. This modern treatment process offers highly effective removal of taste and odor compounds while increasing the system’s resilience to seasonal and climate-driven fluctuations in water quality.