The Amur River rises past 7.35 metres in Khabarovsk city, with Komsomolsk-on-Amur, and Nikolayevsk-on-Amur also braced for new flooding.
The swollen Amur River reached a depth of 910 cm near Komsomolsk-on-Amur on Sunday, with fears it could hit 940cm.
More than 20,000 residents were moved as rivers burst their banks with forecasts of worsening flooding later this week.
Russian army in battle to erect dikes to hold back the swirling Amur River as evacuations begin in low-lying areas.
At least 30,000 homes are hit by flooding in Amur region, with Vladimir Putin ordering more emergency aid to stricken people.
Defences were breached in Komsomolsk-on-Amur engulfing several villages, as forced evacuation rise.
The second largest city of the Russian Far East faces nervous hours and days to see if its dikes hold back the deluge.
Warnings of worse rain for the rest of the week came on Wednesday as evacuation of 30 settlements was planned by the authorities.
Damage from wave of floods already labelled 'catastrophic' with worse to come as Russian president Vladimir Putin demands: 'Put people first'.
Flooding now covers an area almost as large as France, Germany and Britain combined, or close to the equivalent of Texas and California.