Gandhiji’s Dandi march to protest against salt taxes back in 1930 in the pre-independence India is what I consider probably the first citizen science movement of India. Here is my analysis:
Gandhiji at the age of 60, led the peoples or citizens movement to break the salt laws. The movement initially began with about 100 satyagrahis from Sabarmati, increasing upto 4000 in Asali, later into 30,000 in Surat, and elevating upto 50,000 in Dandi.
The Dandi march, a stretch of 390 km, flowing from 4 districts and 48 villages, with about 50,000 people, was completed in 24 days (March 12 — April 6, 1930). (Source for data — Wikipedia article on Dandi March)
Apart from it being a great political movement to protest against paying taxes for salt which was considered as a necessity to each and every Indian, I consider the Dandi March as a citizen science movement in which the participants or the satyagrahis were involved in a scientific process of making salt.
On reaching Dandi, Gandhiji picked up a handful of salt mud and boiled it in seawater, thereby producing salt. The thousands of followers likewise began making salt along the seashore by this simple scientific process.
For some history on the salt laws, taxes, protests, route of the march, one may visit links, read books.