Karnataka is protesting the state government's release of Cauvery river water to Tamil Nadu, based on a Supreme Court directive, with a shut down on Friday.The day-long protest is being spearheaded by as many as 500 pro-Kannada organisations, which represent sections including farmers, traders and businesses. Security has been stepped up and more forces have been deployed across the state.Government offices will remain open, but public transport, including metro services, will not ply. Banks, shops, markets, malls, hotels, bars, pubs, eateries, restaurant, theatres and petrol bunks will also remain closed during the day, officials said.Essential supplies, including milk and medicines, thought, have been exempted from the shutdown. Ambulances will be allowed to ferry patients to hospitals.Bowing to the apex court's Monday order, the state began releasing 15,000 cusecs of water daily from early Wednesday from its reservoirs across the river basin for 10 days amid protests and demonstrations by farmers, traders and the youth in the Mysuru region.