Karnataka's Krishnarajasagara Dam on the river Cauvery is full. There were consecutive years of drought in Karnataka - and it has been years since the dam reached its full level of 124.8 feet - and even longer since it filled up as early as July. The release of water from the dam is a spectacular sight, but it is more than that. It is hugely significant for the thousands of Karnataka farmers who rely on the dam for irrigation, for farmers in the Cauvery delta of Tamil Nadu and for the thirsty cities of the Cauvery basin, including Bengaluru.