Historical clue formulations

• Streaming channel? — 2022-07-15
• Waterway — 2020-01-04
• Sloping water trough — 2016-12-20
• Gated water channel — 2016-03-23
• Water channel — 2001-01-10
• Floodgate — 2000-06-18
• Floodgate — 1999-05-12
• Floodgate — 1998-03-17
• Floodgate — 1997-05-25
• Artificial channel — 1996-10-19