Official sources said the water level of the river had already crossed the danger level of 10.36 m at Rajghat in the district and had touched 11.26 m.
With rains continuing it is apprehended that the water level of the Subarnarekha river would rise to 12.20 m by evening, official reports said.
The Balasore district administration held an emergency meeting to meet the impending situation as the swollen river posed danger to Bhograi, Jaleswar, Basta and Baliapal blocks.
The smaller river Jalaka could flood some portion of Balasore sadar block, Basta and Baliapal, an official said. A report from Baripada said the water level in Bodhabalang river, the major river in neighbouring Mayurbhanj district, was also rising.
Nearly 100 acre of paddy field in Madhuban area near the district headquarters town of Baripada has already been submerged.
The administration of both the districts have been asked to be on alert with the weather office here forcast more rain in the area in the next 24 hours due to a deep depression over Gangetic West Bengal, the sources said.