To mix or not to mix? A holistic approach to stratification-preserving and destratification aeration of drinking-water supply reservoirs

Lee Bryant, Niamh Brockbank, David Austin

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Aeration is used globally as a remediation method for lakes and reservoirs with methods generally falling into two categories, those which preserve natural stratification (hypolimnetic aeration; HA) and those which destratify reservoirs through mixing of the water column (destratification aeration; DA). The United Kingdom and Australia largely focus on DA methods to manage harmful algal blooms and decrease trace metal concentrations, whereas the United States and Europe frequently focus on HA techniques to increase dissolved oxygen (DO) concentrations and decrease benthic nutrient and metal release from the sediment. A more holistic understanding of how the different techniques influence water quality in regard to raw water supply and ecosystem health should lead to more efficient treatment, reducing wasted energy and other costs during both reservoir management and the drinking-water treatment process. This study compares HA and DA on stratification, DO, and cyanobacteria concentrations in a single drinking-water supply reservoir during the 2016 summer stratification period. HA preserved stratification but could not maintain sufficient hypolimnetic DO past late April in this functionally eutrophic reservoir, establishing conditions favourable to cyanobacteria. An incipient cyanobacteria bloom formed that was subsequently dispersed after DA was initiated on May 05. Continuous monitoring revealed the formation of these issues in real-time and informed a switch from HA to DA, thereby allowing for a pro-active rather than reactive approach to reservoir management and subsequent drinking-water treatment. Both HA and DA are put forward as successful aeration strategies depending on management goals; however, performance is strongly site-specific. Such approaches are likely to become increasingly important as reservoir management tools to combat stratification-driven water quality issues under the pressing threats of anthropogenic activity and climate change.

Original languageEnglish
Article number121974
JournalWater Research
Early online date30 Jun 2024
Publication statusE-pub ahead of print - 30 Jun 2024

Data Availability Statement

Data have been made available via GitHub link (in Acknowledgements) and as Supplementary Information.


The authors thank Tampa Bay Water for access to data, critical review and permission to publish, two anonymous reviewers for their helpful feedback, and Gay Bryant for figure support. To support open access, the authors have applied a Creative Commons Attribution (CC-BY) licence to any Author Accepted Manuscript version arising. Data and code supporting this study are provided as Supplementary Information and/or via This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.


  • Aeration
  • Cyanobacteria
  • Destratification
  • Hypolimnetic
  • Oxygen
  • Stratification

ASJC Scopus subject areas

  • Water Science and Technology
  • Ecological Modelling
  • Pollution
  • Waste Management and Disposal
  • Environmental Engineering
  • Civil and Structural Engineering

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