The story connected to Govardhan Pooja and Anna Kootha is as follows:
Lord Indra used to be worshipped during Diwali, in Brajbhoomi. Lord Krishna told the villagers, “There is no point in worshipping Lord Indra at this time because the rains have already ended and Lord Indra is the God of Rains. Worshipping the mountains and the trees would be better for taking care of cows and the progression of their generations. We should also celebrate Van Mahotsav by planting trees and grass. Cow dung should not be burnt. But, it is supposed to be used as manure and worshipped as God. This will result in the progress of human beings as well as the country.”
The villagers began to follow Lord Krishna’s advice and began to celebrate Diwali and Van Mahotsav in a new way. Lord Indra became angry and showered the village with heavy rains for 7 days. Lord Krishna picked up the Govardhan Mountain on His little finger and protected everybody from the deluge. Ultimately, Lord Indra realized that Lord Krishna is none other than Lord Vishnu’s Avtar and came to apologize to Him. He also stopped the incessant rains.
Lord Krishna promoted the growing of vegetarian food from the fields. That is why we offer Anna Kootha as naivedyam to Lord Krishna.
Moral: Lord Krishna is an eco-friendly God. Following His instructions, the environment can be conserved. Unless it is an emergency, we should not burn wood, cow dung and grass. Some people pluck and kill plants as a routine activity. They teach their children also these wrong things. This is a big sin. We have to avoid it.