21.   The snow had just melted and the rivers were in spate.

22.   There were rivers he visited as a child where he could sit and watch water voles every day.

23.   When the river is low, vast stretches of sand are laid bare.

24.   The river is too dangerous to navigate.

25.   ...pumps that guarantee a constant depth of water even when the supplying river is low.

26.   The river was alive with birds.

27.   Rivers are a blessing for an agricultural country.

28.   The rivers are close to flooding.

29.   The river is passable during the summer months.

30.   That is strange, for the boat was moored for the last night and the river was calm.