Sandbag dikes are being built up higher in Regina as city officials prepare for a larger surge of floodwater than earlier expected.

The Saskatchewan Watershed Authority now says the city could see water levels rise one metre higher. Such levels haven't been seen in Regina since 1974.

In response, city crews are adding one-quarter metre of height to sandbag dikes to allow for a 30-centimetre buffer above expected water levels.

The additional sandbags are expected to be in place within the next week.

The city has already deployed more than 40,000 sandbags to protect low-lying areas from floodwaters. Another 20,000 sandbags have been filled and the city plans to double that stockpile.

Most of the sandbag dikes are set up along the south side of Wascana Creek between Albert Street and Pasqua Street.

Water is currently being allowed to flow over the banks of the creek and onto the surrounding flood plain.

Levels on Wascana Lake are expected to peak near the end of next week, depending on the weather.

Photo Gallery: Flood Watch 2011