These datasets were derived from the water samples obtained at the Rabnabad channel, which is located in the Bay of Bengal's upstream region. From March 3rd to 6th 2022, a detailed field survey was conducted. Chlorophyll – a (chl-a) measurements were taken from 32 water samples collected from eight different locations. The sampling was carried out with the help of the Payra Port's vessel 'SAGOR JATRA-1.' Water samples were collected from various depths using a Niskin sampler of HYDRO-BIOS with a non-metallic interior. To obtain in-situ data, water samples were tested in the laboratory according to conventional procedures.  In this channel, a large community relies on fishing as a means of their livelihood.  Understanding the chlorophyll status in this region is crucial because it forms the basis of the food web and serves as an indicator of primary production, which in turn influences secondary output. In order to isolate the pigments from this murky upstream location, a trustworthy extraction technique need to be identified.