| 2026-05-29 | Barriers to entry, in a way |
| 2025-01-26 | Hydroelectric projects |
| 2024-06-18 | Stops up |
| 2023-12-11 | River blockers |
| 2022-07-30 | Holds back, in a way |
| 2021-08-13 | Blocks |
| 2020-09-06 | Stops up |
| 2018-06-01 | Blocks off |
| 2016-11-11 | Civil engineering projects |
| 2016-07-20 | Creators of artificial lakes |
| 2015-02-11 | Challenges for salmon |
| 2014-06-10 | Beaver projects |
| 2013-08-06 | Lake creators |
| 2012-12-25 | Beavers build them |
| 2012-07-19 | Blockades, of a sort |
| 2012-04-08 | Blocks (up) |
| 2011-12-26 | Beaver constructions |
| 2011-10-10 | Projects for beavers |
| 2011-07-10 | Blocks |
| 2011-01-17 | Beaver constructions |
| 2010-03-17 | Reservoir producers |
| 2005-05-22 | Hoover and others |
| 2005-04-07 | Power sources |
| 2004-12-26 | Stops up |
| 2001-12-09 | Blocks |
| 2001-11-22 | Hungry Horse and Mossyrock |
| 2000-07-12 | Farm mothers |
| 2000-04-11 | Stops up |
| 1998-05-03 | Stops up |
| 1997-06-02 | Beavers' constructions |
| 1997-05-03 | Stops up |
| 1995-12-15 | Creek constrictors |
| 1995-08-17 | Hoover and Roosevelt, e.g. |
| 1995-06-12 | Beavers' constructions |
| 1994-10-04 | Beaver projects |