Historical clue formulations

• Ethiopia's Lake ___ — 2022-08-21
• Largest lake in Ethiopia — 2022-03-16
• Lake from which the Blue Nile begins — 2012-09-01
• Lake ___ (Blue Nile source) — 2011-07-15
• Lake ___, head of the Blue Nile — 2010-09-16
• Lake ___ (Blue Nile source) — 2003-04-19
• Lake ___ (Blue Nile source) — 1999-08-20
• Lake from which the Blue Nile springs — 1995-01-29