Occurrence of Attributes in Original Text

The text related to the cultural heritage 'Mill Network at Kinderdijk-Elshout' has mentioned 'Reservoir' in the following places:
Occurrence Sentence Text Source
It was decided to build a series of windmills, with a limited capacity to bridge water level differences, but just able to pump water into a reservoir at an intermediate level between the soil in the polder and the river.
The reservoir could be pumped out into the river by other windmills whenever the river level was low enough; the river level has both seasonal and tidal variations.
The reservoir system of both is also intact, the lower reservoir of De Nederwaard dating back to 1369 and that of De Overwaard to 1365.