Historical clue formulations

• Underground waterway — 2025-09-30
• Underline? — 2025-05-31
• Waste conduit — 2024-05-28
• Waste's way away — 2024-03-07
• Pipe down? — 2023-08-27
• Frequent setting for the Ninja Turtles — 2023-06-15
• Part of an underground system — 2023-06-03
• "The sea is the universal ___": Jacques Cousteau — 2023-04-22
• Ninja Turtles' abode — 2022-11-20
• Ninja turtle hangout — 2022-06-21
• Waste line — 2022-04-14
• Home for the Teenage Mutant Ninja Turtles — 2021-10-05
• What may raise a big stink? — 2021-04-14
• Underground channel — 2020-02-09
• Waste conduit — 2016-10-24
• Part of a city network — 2016-05-29
• Runoff conduit — 2014-08-20
• Something beyond the grate divide? — 2013-10-05
• Waste carrier — 2013-09-23
• "Ratatouille" setting — 2012-03-08
• Drainage system — 2011-10-04
• Waste line — 2010-01-17
• Stinky stream — 2008-07-21
• Storm drain, e.g. — 2008-02-13
• Place of refuse — 2007-08-25
• It may be found under a grate — 2007-03-25
• Ratty place — 2006-11-22
• Rats' milieu — 2006-10-10
• "Les Misérables" locale — 2006-08-26
• Stinky locale to work — 2006-08-22
• Waste conduit — 2006-08-15
• Waste conduit — 2004-12-13
• System utilizing grates — 2004-01-26
• Valjean's hideout — 2003-10-11
• Job title (giving a hint to this puzzle's theme) — 2003-01-13
• Setting for a famous "Les Misérables" scene — 2003-01-01
• Underground conduit — 2002-11-04
• Ed Norton's workplace — 2002-02-05
• Rats' hangout — 2001-06-27
• Ratty place — 2001-01-21
• Urban alligator's home, they say — 1999-04-04
• Drainage system — 1998-07-30
• "Les Miz" setting — 1997-01-19
• Drain — 1996-12-31
• Underground passage — 1996-11-18
• Drain — 1995-06-02
• Underground way — 1995-01-17
• "Les Miz" setting — 1994-12-02
• Betsy Ross, e.g. — 1994-04-26
• Culvert — 1994-03-12