The much anticipated meeting of the Cauvery Monitoring Committee on Thursday decided that Tamil Nadu will get 8.85 thousand million cubic feet of water over the next fortnight.
Karnataka said it would not accept the award.
The award of the committee is based on the findings of a central team that visited Karnataka and Tamil Nadu last week.
Sources said the award is clear that Tamil Nadu "shall receive" 8.85 thousand million cubic feet of water between October 16 and October 31.
"Karnataka may also not have to release water from its reservoirs. It may be available in the catchment areas," an official said.
He said the CMC will meet again on October 29 to review the situation and much would depend on the north-east monsoon, which is likely to hit Tamil Nadu.
"If the monsoon is successful, the decision could be changed with effect from October 29 itself," he said.
In September, the Cauvery River Authority, chaired by the prime minister, had directed Karnataka to release 9,000 cusecs of water daily to Tamil Nadu between September 20 and October 15.
The CMC was to decide on the availability of water for Tamil Nadu after October 15.
Though it is only an interim award, the Karnataka government is free to approach the CRA or the Supreme Court seeking a review, the sources said.
Karnataka government has urged Prime Minister Manmohan Singh to review by October 12 the order of the CRA directing the state to release 9,000 cusecs of water to Tamil Nadu.
In a letter to Union Water Resources Minister P K Bansal, copies of which were released to the press in Bangalore, state Water Resources Minister Basavaraj Bommai noted that the prime minister has the power to review the decision under Inter-State River Water Disputes Act.
Concerned over the plight of Tamil Nadu farmers due to the Cauvery crisis, Union Shipping Minister G K Vasan on Thursday appealed to the prime minister to urge Karnataka to release water from its dams to Tamil Nadu.
"Karnataka not releasing water to Tamil Nadu is a wrong decision which should not be allowed," he said.