Biology at SCC
Freshwater Ecology & Watershed Research

Cyanobacteria · Chapter 9

Cyanobacteria in Kentucky

Outline · full text in Phase 2 Last reviewed 2026-11-05

Learning objectives

After studying this chapter, you should be able to:

  1. Summarize documented Kentucky HAB events and how advisories are issued.
  2. Describe Kentucky's freshwater settings: large reservoirs, the Ohio River, small lakes and farm ponds, karst streams.
  3. Distinguish documented Kentucky findings from hypotheses about Allen Branch or Lake Cumberland.
This chapter is an outline The introduction, planned sections, key terms and references below are reviewed and citable. Full textbook text for each section will be added in Phase 2.

Kentucky's waters include the Ohio River along its northern border, very large reservoirs built by the U.S. Army Corps of Engineers and the Tennessee Valley Authority, smaller lakes that supply drinking water, many farm ponds, and streams and springs in extensive karst landscapes. Each setting presents different cyanobacterial questions. This chapter separates what is documented about cyanobacteria in Kentucky from what is hypothesized — especially about the Somerset area, where documented information is scarce.

The documented record begins, in the Cabinet's public releases, in 2013, and includes large blooms on the Ohio River in 2015 and 2019 that led to recreational advisories along Kentucky's northern border [1, 2, 3]. Peer-reviewed Kentucky literature on cyanobacteria is thin — mostly veterinary case reports, one urban-pond study and one reservoir experiment [4, 5, 6, 7] — while nutrient studies in Kentucky's agricultural and karst basins are more extensive [8, 9, 10, 11].

The documented record

The items below are documented in Kentucky Energy and Environment Cabinet news releases or peer-reviewed literature. They are a starting record, not a complete history.

Selected documented harmful algal bloom events and findings in Kentucky
YearWater bodyWhat is documentedSource
1989 (report)Farm pond (county not stated in abstract)Toxicosis in finishing pigs attributed to a bloom identified as Anabaena spiroides[4]
2012–2013Urban ponds, Northern KentuckyYear-round Microcystis-dominated blooms; toxin did not always track cell counts[6]
2013Taylorsville Lake and other U.S. Army Corps of Engineers lakesCorps identified a HAB at Taylorsville; elevated cyanobacteria at several Corps lakes led the Division of Water to test 14 more lakes[1, 12]
2013Two livestock pondsFifteen cattle died; microcystin-LR detected in one pond and in rumen samples[5]
2015Ohio RiverRecreational advisory from the West Virginia line downstream to the Cannelton Locks and Dam[2, 13]
2016Boltz Lake, Grant CountyPublic health watch upgraded to warning[14, 15]
2019Ohio River; Briggs LakeAdvisory from McAlpine Dam to Greenup Dam, and for Briggs Lake near Russellville[3]
2021 (study)Guist Creek Lake water (microcosms)Added nitrogen, not phosphate alone, increased cyanobacteria at the time sampled[7]
2026Old Springfield ReservoirHarmful algal bloom confirmed[16]
What we did not find A search of peer-reviewed literature, USGS publications and the Cabinet's news releases (November 2026) found no study of cyanobacteria or cyanotoxins in Lake Cumberland or in Pulaski County streams. The nearest comparable work is downstream on the Cumberland River system in Tennessee, where USGS and state monitoring in a karst landscape detected at least one cyanotoxin at every one of 18 sites [17], and where microcosm experiments showed nitrogen and phosphorus co-limitation [18]. Absence of published studies is not evidence that blooms do not occur; it means the question is open.

Planned sections

9.1 Kentucky's freshwater environments

Large mainstem reservoirs (such as Kentucky Lake and Lake Cumberland), smaller water-supply lakes, the Ohio River, farm ponds, and karst streams and springs. Long-term nutrient and chlorophyll studies exist for Kentucky Lake [19, 20].

9.2 Historical HAB monitoring

From cell-count thresholds in 2013–2014 to toxin-based watch and warning levels by 2015–2016 (Chapter 5) [12, 21, 13, 15].

9.3 Major reservoirs and smaller ponds

Corps of Engineers lakes, municipal reservoirs and farm ponds; livestock cases from ponds [4, 5].

9.4 Agricultural watersheds

Statewide nutrient concentrations, loads and yields; agricultural versus forested basins [8, 11].

9.5 Karst and groundwater

Higher nutrient concentrations in intensely karst basins; slow response of a karst spring to best-management practices [8, 10].

9.6 Seasonal conditions

Summer low flow and warm temperatures on large rivers; seasonal nutrient peaks after fertilizer application [22, 9].

9.7 Public-health monitoring

Joint advisories by the Division of Water and Department for Public Health [3]; EPA guidance values; current thresholds to be confirmed with the Division of Water [23].

9.8 Relevant Kentucky and regional research

Ohio River risk modeling and USGS large-river sampling [22, 24]; Cumberland River studies in Tennessee [17, 18].

9.9 Remaining scientific questions

Lake Cumberland and its tributaries; benthic cyanobacteria in Kentucky streams; farm-pond surveys; links between karst nutrient delivery and cyanobacteria (Chapter 10).

Connection to local research

At Allen Branch and nearby waters

Hypothesis The Pitman Creek embayment of Lake Cumberland, where the USGS map routes the Allen Branch–Sinking Creek–Pitman Creek path, is the nearest place where planktonic cyanobacteria could plausibly bloom. Nothing is documented there in the sources reviewed for this chapter.

Allen Branch itself is not a documented bloom site. See the site profile and Chapter 10.

Key terms

Advisory
Public notice recommending people avoid certain water contact.
Watch / warning
Kentucky's two-tier advisory levels described in 2016 releases.
Karst
Landscape of dissolved limestone with sinkholes, springs and conduits.
Mainstem reservoir
A reservoir formed by damming a large river.

References

  1. Kentucky Energy and Environment Cabinet (2013). Public Advised of Potential Health Risks with Exposure to Water in Taylorsville Lake. Naturally Connected (Cabinet news). https://kydep.wordpress.com/2013/06/28/public-advised-of-potential-health-risks-with-exposure-to-water-in-taylorsville-lake/ (accessed 2026-11-05)
  2. Kentucky Energy and Environment Cabinet (2015). Recreational advisory issued for Ohio River due to harmful algal bloom. Naturally Connected (Cabinet news). https://kydep.wordpress.com/2015/09/18/recreational-advisory-issued-for-ohio-river-due-to-armful-algal-bloom/ (accessed 2026-11-05)
  3. Kentucky Energy and Environment Cabinet (2019). Harmful Algal Bloom Recreational Public Health Advisory Issued. Naturally Connected (Cabinet news). https://kydep.wordpress.com/2019/09/26/harmful-algal-bloom-recreational-public-health-advisory-issued/ (accessed 2026-11-05)
  4. Chengappa, M. M., Pace, L. W., & McLaughlin, B. G. (1989). Blue-green algae (Anabaena spiroides) toxicosis in pigs. Journal of the American Veterinary Medical Association, 194(12), 1724-1725. https://doi.org/10.2460/javma.1989.194.12.1724
  5. Moore, C., Juan, J., Lin, Y., Gaskill, C., & Puschner, B. (2016). Comparison of Protein Phosphatase Inhibition Assay with LC-MS/MS for Diagnosis of Microcystin Toxicosis in Veterinary Cases. Marine Drugs, 14(3), 54. https://doi.org/10.3390/md14030054
  6. de la Cruz, A., Logsdon, R., Lye, D., Guglielmi, S., Rice, A., & Kannan, M. S. (2017). Harmful Algae Bloom Occurrence in Urban Ponds: Relationship of Toxin Levels with Cell Density and Species Composition. Journal of Earth and Environmental Science, 25, 704-726. https://pmc.ncbi.nlm.nih.gov/articles/PMC6865815/ PMID 31750421; PMCID PMC6865815. The DOI printed on the PubMed record (10.29011/JEES-148.100048) did not resolve when checked, so it is cited by PMCID.
  7. Hughes, S. E., & Marion, J. W. (2021). Cyanobacteria Growth in Nitrogen- & Phosphorus-Spiked Water from a Hypereutrophic Reservoir in Kentucky, USA. Journal of Environmental Protection, 12(02), 75-89. https://doi.org/10.4236/jep.2021.122006
  8. Crain, A. S., & Martin, G. R. (2009). Concentrations, and estimated loads and yields of total nitrogen and total phosphorus at selected water-quality monitoring network stations in Kentucky, 1979-2004. U.S. Geological Survey Scientific Investigations Report 2009-5240. https://doi.org/10.3133/sir20095240
  9. Crain, A. S. (2010). Nutrients, Select Pesticides, and Suspended Sediment in the Karst Terrane of the Sinking Creek Basin, Kentucky, 2004-06. U.S. Geological Survey Scientific Investigations Report 2010-5167. https://doi.org/10.3133/sir20105167
  10. Currens, J. (2002). Changes in groundwater quality in a conduit-flow-dominated karst aquifer, following BMP implementation. Environmental Geology, 42(5), 525-531. https://doi.org/10.1007/s00254-001-0515-6
  11. Crain, A. S., Cherry, M. A., Williamson, T. N., & Bunch, A. R. (2017). Multiple-source tracking: Investigating sources of pathogens, nutrients, and sediment in the Upper Little River Basin, Kentucky, water years 2013–14. U.S. Geological Survey Scientific Investigations Report 2017-5086. https://doi.org/10.3133/sir20175086
  12. Kentucky Energy and Environment Cabinet (2013). Harmful algal blooms found at four more Kentucky lakes. Naturally Connected (Cabinet news). https://kydep.wordpress.com/2013/10/21/harmful-algal-blooms-found-at-four-more-kentucky-lakes/ (accessed 2026-11-05)
  13. Kentucky Energy and Environment Cabinet (2015). Recreational Advisory for lower McAlpine pool of Ohio River lifted after results below advisory level. Naturally Connected (Cabinet news). https://kydep.wordpress.com/2015/10/09/recreational-advisory-for-lower-mcalpine-pool-of-ohio-river-lifted-after-results-below-advisory-level/ (accessed 2026-11-05)
  14. Kentucky Energy and Environment Cabinet (2016). Harmful Algal Bloom Public Health Watch Issued for Boltz Lake in Grant County. Naturally Connected (Cabinet news). https://kydep.wordpress.com/2016/09/02/harmful-algal-bloom-public-health-watch-issued-for-boltz-lake-in-grant-county/ (accessed 2026-11-05)
  15. Kentucky Energy and Environment Cabinet (2016). Harmful Algal Bloom Public Health Watch Upgraded to Warning for Boltz Lake in Grant County. Naturally Connected (Cabinet news). https://kydep.wordpress.com/2016/09/22/harmful-algal-bloom-public-health-watch-upgraded-to-warning-for-boltz-lake-in-grant-county/ (accessed 2026-11-05)
  16. Kentucky Energy and Environment Cabinet (2026). Harmful Algal Bloom Confirmed on Old Springfield Reservoir. Naturally Connected (Cabinet news). https://kydep.wordpress.com/2026/10/28/harmful-algal-bloom-confirmed-on-old-springfield-reservoir/ (accessed 2026-11-05)
  17. Hill, K. L., Jaegge, A. C., Moore, D. M., & Byl, T. D. (2026). Tracking Toxins: A Pilot Investigation of Cyanotoxins in North-Central Tennessee’s Surface Waters and Wells. Toxins, 18(6), 239. https://doi.org/10.3390/toxins18060239
  18. Li, J., & Murdock, J. (2025). Nutrient concentration, stoichiometry, and timing of delivery can regulate cyanobacterial dominance and microcystin production in rivers. Journal of Environmental Management, 377, 124714. https://doi.org/10.1016/j.jenvman.2025.124714
  19. Yurista, P. M., White, D. S., Kipphut, G. W., Johnston, K., Rice, G., & Hendricks, S. P. (2004). Nutrient Patterns in a Mainstem Reservoir, Kentucky Lake, USA, Over a 10-year Period. Lake and Reservoir Management, 20(2), 148-163. https://doi.org/10.1080/07438140409354359
  20. Tumolo, B. B., & Flinn, M. B. (2017). Top-down effects of an invasive omnivore: detection in long-term monitoring of large-river reservoir chlorophyll-a. Oecologia, 185(2), 293-303. https://doi.org/10.1007/s00442-017-3937-x
  21. Kentucky Energy and Environment Cabinet (2014). Division of Water lifts Harmful Algal Bloom Advisory for six Kentucky Lakes. Naturally Connected (Cabinet news). https://kydep.wordpress.com/2014/10/28/division-of-water-lifts-harmful-algal-bloom-advisory-for-six-kentucky-lakes/ (accessed 2026-11-05)
  22. Nietch, C. T., Gains-Germain, L., Lazorchak, J., Keely, S. P., Youngstrom, G., Urichich, E. M., Astifan, B., et al. (2022). Development of a Risk Characterization Tool for Harmful Cyanobacteria Blooms on the Ohio River. Water, 14(4), 644. https://doi.org/10.3390/w14040644
  23. U.S. Environmental Protection Agency (2026). State & Tribal Toxin Thresholds. U.S. EPA Harmful Algal Blooms program. https://www.epa.gov/habs/state-tribal-toxin-thresholds (accessed 2026-11-05) Accessed 2026-11-05: the table lists Kentucky as 'No Thresholds' for drinking water and recreation, with the caveat that only publicly accessible thresholds are listed.
  24. Zuellig, R. E., Graham, J. L., Stelzer, E. A., Loftin, K. A., & Rosen, B. H. (2021). Cyanobacteria, cyanotoxin synthetase gene, and cyanotoxin occurrence among selected large river sites of the conterminous United States, 2017–18. U.S. Geological Survey Scientific Investigations Report 2021-5121. https://doi.org/10.3133/sir20215121