A red alert has been issued for Sholayar, Peringalkuthu, Kundala, Kallarkutty, and Moozhiyar dams.
The dam is now maintained by the state government under the Periyar valley project, and some areas of the famous Thattekad bird sanctuary touch the dam waters.
Fishermen should not venture out into the sea on Monday as strong winds are likely.
The reservoirs have almost double the water compared with the year-ago corresponding date.
In a directive issued to the KSEB and Department of Irrigation, the government ordered the authorities to maintain water levels in major dams scientifically based on the rule curve.
KSEB Chairman N S Pillai said the current situation did not warrant raising the shutters of dams, including Idukki, under the board.
Tamil Nadu has demanded raising the water level in the dam from 142 feet to 152 feet, thereby signalling that the existing dam has the strength to hold a larger volume.
The site for the proposed dam has been identified 366mts downstream of the existing dam. The new dam will be constructed within the limits of the Periyar Tiger Reserve.
The DPR prepared 10 years ago is reportedly being revised.
The base of the dam was constructed using concrete fixed with 'surkhi' made of jaggery, sugarcane juice, egg white and lime.