**4. Discussion**

Rainwater harvesting is a green method of providing water for agricultural practices, since having access to adequate and safe irrigation water is crucial for the success of farming operations. Harvesting of rainwater is also known for a being straightforward, economical, and innovative solution contributing to sustainability and resilience of water sources. Rainwater is considered a high-quality source of irrigation because it is nearly sodium-free and has a low sodium adsorption ratio, which helps to maintain the physical structure of the soil [2]. On the other hand, there could be some other constituents such as emerging untraditional substances which pose a significant challenge to the use of

rainwater harvesting for irrigation. Cyanotoxins are one of these components that threaten the ecosystem health.

Certain types of cyanobacteria can excrete toxins that damage the liver (hepatotoxins), harm the nervous system (neurotoxins), and damage cell integrity (cytotoxins) [9]. *Microcystis*, *Aphanizomenon*, *Dolichospermum*, *Planktothrix*, and *Cuspidothrix* are known genera-producing cyanotoxins [10–12]. Irrigation with water that contains cyanotoxins can have negative impacts on the quality and yield of agricultural plants. Since there is not any treatment for these components, these toxins can bioaccumulate in plant tissues. Subsequently, they may enter the food chain with the edible plants and pose environmental and human health risks [9]. Accumulation can vary depending on the type of plant and irrigation method used [13]. Overall, it was found that two ponds were not proper for irrigation purposes. To increase the water quality in these reservoirs, onsite managemen<sup>t</sup> strategies should be taken into consideration.

**Author Contributions:** Conceptualization, R.A. and M.A.; methodology, E.G.O., L.K. and A.O.Ç.; investigation, E.G.O., L.K. and A.O.Ç.; writing—original draft preparation, R.A., M.A., E.G.O., L.K. and A.O.Ç.; writing—review and editing, R.A., M.A., E.G.O., L.K. and A.O.Ç.; visualization, E.G.O.; project administration, E.G.O. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was funded by the Scientific Research Projects Coordination Unit of Istanbul University, gran<sup>t</sup> number FBG-2022-38851.

**Institutional Review Board Statement:** Not applicable.

**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** Not applicable.

**Acknowledgments:** The authors kindly acknowledge Hakan Korkusuz for his kind help in sampling.

**Conflicts of Interest:** The authors declare no conflict of interest.
