Water levels on the Danube in early July-is it usually a problem

At that time of year?

Was thinking of doing early June but there are some big discounts in July and wondering if it is because there is a greater risk of water levels being lower.

Water levels on the Danube are as impossible to predict as the weather, especially at this long range. All the cruise companies are well versed in dealing with both high and low water and you may have to do some of the trip by coach. Below Budapest toward the Black Sea is usually where most problems if any occur.

This site is interesting to explore - http://www.marinetraffic.com/ais/default.aspx?level0=100