YOU SAID:

The water was rising as high speed

INTO JAPANESE

水位は猛スピードで上昇していた

BACK INTO ENGLISH

The water level was rising at a rapid rate

INTO JAPANESE

水位が急激に上昇していました

BACK INTO ENGLISH

The water level was rising rapidly

INTO JAPANESE

水位が急激に上昇していました

BACK INTO ENGLISH

The water level was rising rapidly