Adaptive level control systems for maximizing stormwater pond functionality

Project overview

In urban settings, space for new stormwater features at grade is often limited, and building new underground systems can be prohibitively expensive. In these cases, retrofitting existing stormwater infrastructure with Adaptive Level Control Systems (ALCS) instead of building new features can allow stormwater professionals to improve the performance of stormwater management systems within the constraints of limited space and tight budgets. These adaptive systems respond to observational data, such as flow and water level conditions, weather forecasts, and hydrologic models. This connectivity allows ALCS to adaptively alter pond outlet structures in response to current and predicted conditions. By controlling flow rates and water levels, ALCS increase sediment and nutrient capture in ponds and reduce erosive energy in the downstream flow, improving the primary functions of existing stormwater ponds. 

However, ALCS are relatively new, providing engineers with little precedent when designing ALCS retrofits. Additionally, permitting processes may not adequately evaluate plans that include ALCS systems. To address these challenges, the research team undertook a comprehensive literature review that summarizes current knowledge related to: the performance of ALCS, regulatory barriers, examples of established pathways to regulatory approval, co-benefits, ownership and operation models for multiple stakeholders, designing and testing algorithms, and costs. Then, the team conducted additional research to provide planners and stormwater managers with practical methods for estimating the costs and evaluating the feasibility ALCS projects in Minnesota. 

Research questions

  • What are the recommended approaches and considerations for implementing ALCS in Minnesota?
  • How does the cost of retrofitting ALCS to existing stormwater BMPs compare to construction of other traditional BMPs?

Research findings

  1. This project developed an ALCS implementation process that meets Minnesota’s unique regulatory frameworks, hydrologic conditions, and institutional structures. This process consists of five phases:
    1. ALCS Opportunity Identification
    2. Planning and Feasibility Study
    3. Design and Permitting
    4. Installation and Commissioning
    5. Operation, Monitoring, and Maintenance
      Each phase is described in detail in chapter six of the project’s final report. The report includes a table of potential scenarios and potential impacts to consider, as well as a thorough description of the regulations and permitting processes that will likely be triggered by an ALCS retrofit project.
  2. ALCS can substantially improve the effectiveness of existing BMPs, achieving equivalent outcomes for a fraction of the cost of constructing new BMPs, particularly in developed urban and suburban areas. 
     

Key innovations/contributions

This project helps us understand the degree to which adaptive level control systems are effective at reducing contaminant load and mitigating flooding when space is limited and budgets are tight. 

What does this mean for Minnesota?

This project provided practitioners with a roadmap to designing and permitting their own ALCS. With this information, ALCS will become a more accessible option for stormwater managers, giving practitioners more adaptive, flexible, and responsive systems that do a better job at reducing runoff volume and improving water quality.  

Project assets

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Project assets

Reports and Presentations

Media coverage

"How Adaptive Level Control Systems are Transforming Flood Management" Barr Insights, February 3, 2026