Exodus 7:19

The “streams” mean the natural branches of the Nile in Lower Egypt. The word “rivers” should rather be “canals”; they were of great extent, running parallel to the Nile, and communicating with it by sluices, which were opened at the rise, and closed at the subsidence of the inundation. The word rendered “ponds” refers either to natural fountains, or more probably to cisterns or tanks found in every town and village. The “pools”, literally “gathering of waters,” were the reservoirs, always large and some of enormous extent, containing sufficient water to irrigate the country in the dry season.