A Case Study on Blue Algae in Malampuzha Dam

Abstract

Blue-green algae, or cyanobacteria, are photosynthetic bacteria that thrive in nutrient-rich water bodies. Although they contribute to oxygen production and support aquatic ecosystems, their excessive growth can lead to harmful algal blooms that release toxins, endangering humans, animals, and water quality. Exposure to these toxins may occur through drinking. swimming, or inhalation, causing health effects such as skin irritation, gastrointestinal issues, liver damage, and in rare cases, neurological symptoms. Contaminated water spray can also trigger respiratory problems, and fish and shellfish may become unsafe to consume. Additionally, algal blooms can degrade the taste, Odor, and safety of drinking water, complicating treatment processes. A case in point is Vellayaniv Lake in Thiruvananthapuram and Malampuzha dam, which is affected by eutrophication due to nutrient overload and invasive vegetation, resulting in cyanobacterial blooms and ecological decline. Despite ongoing restoration efforts, sustained monitoring, pollution control, and community participation are essential to improve the lake\'s health and ensure safe water quality. Effective removal methods used in water treatment plants include physical techniques like filtration and flotation, chemical treatments such as chlorination and ozonation, and advanced methods like activated carbon adsorption and membrane filtration. Long-term control also involves biological strategies and reducing nutrient pollution at the source

Introduction

This study investigates algal blooms and their environmental impacts in Malampuzha Dam and Vellayani Lake, focusing on their causes, occurrence, and management strategies to support sustainable water resource management. Algal blooms occur mainly due to nutrient enrichment, climate conditions, and human activities, which degrade water quality and threaten aquatic ecosystems. The research is organized into five main sections: Background and Objectives, Literature Review, Methodology, Results and Analysis, and Future Work.

A site visit to Malampuzha Dam was conducted to observe reservoir conditions, including water inlet and outlet points, stagnant water zones, catchment areas, and human activities such as tourism and boating. These observations help identify factors contributing to algal growth, including nutrient inflow, seasonal water level variations, temperature changes, and circulation patterns.

The scope of the study highlights the importance of controlling algal blooms for several reasons. Uncontrolled algae lead to eutrophication, reduce dissolved oxygen, and harm aquatic life. Harmful algae can also release toxins that affect drinking water quality, causing bad taste, odor, and discoloration. In addition, contaminated water can pose public health risks such as diarrhea and liver damage, and can negatively affect agriculture by clogging irrigation systems and reducing crop productivity.

Water samples were collected from multiple locations in the reservoir and analyzed in the laboratory. Several water quality tests were conducted, including turbidity, pH, dissolved oxygen, chloride concentration, and microscopic analysis. Results showed acceptable turbidity (0.3 NTU) and pH (7.26), but chloride levels exceeded the acceptable limit. Microscopic examination confirmed the presence of Microcystis, a blue-green algae species that produces microcystin toxins harmful to human health and aquatic organisms.

The study identifies major sources of algal blooms, particularly agricultural runoff and dairy farming activities in the surrounding catchment area. Agricultural fields around the dam use fertilizers and pesticides that release nitrogen and phosphorus into the reservoir during rainfall, leading to Eutrophication, which stimulates rapid algal growth. Similarly, poorly managed dairy farm waste such as manure and urine contributes additional nutrients that enter the reservoir through surface runoff.

These nutrient inputs cause excessive algae growth, reduce oxygen levels, degrade water quality, harm fish populations, and increase water treatment costs. The research emphasizes that effective algal management, nutrient control, and sustainable watershed practices are essential to protect water resources, maintain ecological balance, and ensure safe drinking and irrigation water.

Conclusion

This case study concludes that the occurrence of blue-green algal (cyanobacterial) blooms in Malampuzha Dam is primarily the result of nutrient enrichment caused by human activities within the catchment area. Agricultural runoff, fish cultivation, and dairy farming significantly increase the inflow of nitrogen and phosphorus into the reservoir, accelerating eutrophication and creating favorable conditions for the dominance of harmful algae such as Microcystis. The study also confirms that excessive algal growth adversely affects water quality by increasing turbidity, producing foul Odor and taste, releasing toxins, and disturbing the natural dissolved oxygen balance. These impacts pose serious risks to public health, aquatic life, irrigation practices, and drinking water supply. Moreover, frequent algal blooms lead to clogging and damage of water treatment plant components, resulting in repeated operational failures, higher maintenance costs, and difficulty in repair. Although existing water treatment methods can reduce algal presence to some extent, they are not sufficient as standalone solutions. Therefore, effective long-term management of algal blooms in Malampuzha Dam requires controlling nutrient pollution at the source through improved agricultural practices, proper management of fish farming and dairy waste, continuous water quality monitoring, and public awareness. An integrated and sustainable watershed management approach is essential to restore ecological balance and ensure safe and reliable water resources for the future

References

[1] Jiangping Li et al., (2013); “Study on Algae Removal from Lake Water Using Ultrasound,” Desalination and Water Treatment, Vol. 51, pp. 5329-5338. [2] Faith A. Kibuye et al., (2021); “Critical Review on Cyanobacterial Bloom Control Strategies,” Harmful Algae, Vol. 108, 102099, doi:10.1016/j.hal.2021.102099. [3] Qiaohui Shen et al., (2011); “Enhanced Algae Removal by Chlorination and Coagulation,” Desalination, Vol. 271, pp. 236-240. [4] Lei Wang et al., (2024); “Mechanism Analysis of Cationic Modified Dextran Flocculant for Blue Algal Bloom Treatment,” International Journal of Biological Macromolecules, Vol. 254, Part 3, 128002. [5] Wu et al., (2012); “Hybrid Hydrodynamic Cavitation and Ozonation for Blue-Green Algae Removal,” Journal of Hazardous Materials, Vol. 233-234, pp. 122-128.

Copyright

Copyright © 2026 Hanna K, Mohammed Jabir CK , Sana Parvin PK , Shamil VM. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.