This dataset includes measurements of groundwater levels (2019–2021) and rainfall data (2020–2021), collected through citizen participation on the Indian Ocean island of Karainagar, Sri Lanka. Karainagar, the study area, is one of seven islands located off the coast of Jaffna in northern Sri Lanka. This rectangular island is bounded on three sides by the Palk Strait, while the fourth side faces the Jaffna Lagoon and is connected to the mainland by a causeway. Karainagar covers an area of approximately 22 km², including inland water bodies. Seven dug wells used for domestic purposes were inventoried and monitored to track groundwater levels. Rainfall data were collected from six locations, including two schools, three households, and one village government office (Grama Niladhari Office). Full details about this dataset can be found at https://doi.org/10.5285/bce114d8-8f3b-49e0-90c6-f0788c1e9a0d
