Project overview
The large variability in pond performance observed in field studies suggests that environmental factors interact with pond designs to influence specific hydrologic and water quality outcomes. These relationships are as yet poorly known. While the indiscriminate or unguided use of ponds to manage all stormwater problems may lead to poor outcomes (James et al. 1987), improved design for new ponds and modification of the many existing aging ponds can lead to better performance outcomes. Useful information can be extracted from a rapidly growing research to more effectively inform pond design and management. The purpose of this review is to provide a systematic assessment of the scientific literature investigating the effectiveness of stormwater ponds with respect to multiple performance measures. The review summarizes the research that has been conducted on stormwater ponds to date to provide a synthetic understanding of pond functioning and to identify critical knowledge gaps where further research is needed.
Research findings
Stormwater ponds are key for managing urban runoff and improving water quality, yet many functional aspects remain poorly understood. Research gaps fall into two categories:
Part I: Understanding Pond Function
- Biogeochemical Processes:
- Better understanding needed for nitrogen cycling, especially organic N and denitrification.
Internal phosphorus loading from sediments remains a major unknown. - Vegetation effects on nutrient retention and release require further study.
- Greenhouse gas emissions and potential for carbon burial merit attention.
- Interactions between chloride and metals may lead to pollutant release.
- Better understanding needed for nitrogen cycling, especially organic N and denitrification.
- Physical & Hydrologic Dynamics:
- Impacts of pond shape, depth, mixing, and stratification on pollutant removal.
- Road salt creates persistent chemo-stratification, affecting mixing and oxygen levels.
- More research needed on climate-driven changes (e.g., warmer winters, storms).
- Harmful Algal Blooms (HABs):
- HABs in ponds are understudied despite their health risks and potential to affect downstream waters.
- HABs in ponds are understudied despite their health risks and potential to affect downstream waters.
- Seasonal & Climate Effects:
- Snowmelt and winter inputs can reduce treatment performance.
- Year-round monitoring is needed to assess long-term and seasonal variation.
Part II: Assessment, Modification, and Design Improvements
- Assessment Tools: Develop rapid, cost-effective methods to evaluate aging pond performance.
- Chemical Treatments: Optimize phosphorus treatments (e.g., alum, iron, spent lime, etc.) for reducing pollutants.
- Oxygen Management: Research on aeration and plant-driven oxygen fluctuations is needed to guide design.
- Structural Retrofits: Baffles, filters, and outlet changes show promise but require field validation and maintenance studies.
- Sediment Forebays: Effective for coarse sediment and phosphorus, but their long-term cost, pollutant toxicity, and maintenance need more study.
- Real-Time Control: Few field tests exist; promising for adapting to snowmelt and climate variability.
- Watershed-Scale Planning: Coordinated stormwater control measure (SCM) design improves flow and pollutant reduction but more research is needed on site optimization and cross-jurisdictional collaboration.
What does this mean for Minnesota?
This project offers a comprehensive review of scientific research on stormwater ponds, evaluating their effectiveness across multiple performance measures. By synthesizing current knowledge and identifying key gaps, it provides a clearer understanding of how these systems function, and where our understanding falls short. The insights gained will help guide future research toward the areas of greatest need and impact in Minnesota.
Project assets
Reports and presentations
- Final report 2022 .pdf