Historical clue formulations

• A shore thing to happen — 2018-11-08
• Cyclic recession — 2014-11-08
• Time when the water's low — 2013-04-22
• Refluent phenomenon — 2007-01-27
• Good time to collect seashells — 2005-12-18
• Shallow period — 2005-09-22
• Outflow — 2003-11-23
• Shore leave? — 1998-08-21
• It's on its way out — 1997-09-28
• Drop in the ocean? — 1995-09-01