[Goose]

That diversion dam has not been operable since the 1930s and was removed to restore the steelhead run in the creek.  So all the times any of us have seen a full Lake Lag it has been after that dam ceased to work.  I hope that means that we can all expect to occasionally see a full Lake Lag from time to time.

Do you have a reference for this? While Wikipedia has been known to be in error, take a look at https://en.wikipedia.org/wiki/Lake_Lagunita (which I should have done before I asked my question :-). It says the lake was artificially filled until the "the late 1990s". I guess they could have been getting the water from somewhere else, but I can't imagine where. There was a fish ladder installed on the dam in the 1950s. https://news.stanford.edu/2019/02/27/sta...rsion-dam/ That doesn't prove it was functional at that point, but if it wasn't I would expect just making a big hole would have been the way to go.

In any case the 2017 lake would have been the local runoff, not any "intentional filling". The following is "interesting" in that regard.
https://www.quora.com/Why-is-Lake-Laguni...ger-filled This answer implies that as late as 2017 Stanford had at least the theoretical ability to fill the lake. The problem with the porous lake bottom supposedly goes back a long way. I have heard it was caused by plowing up the bottom of the lake to plant a victory garden during WWII. Have no idea if that is actually so.

[Goose]

That diversion dam has not been operable since the 1930s and was removed to restore the steelhead run in the creek.  So all the times any of us have seen a full Lake Lag it has been after that dam ceased to work.  I hope that means that we can all expect to occasionally see a full Lake Lag from time to time.

Do you have a reference for this? While Wikipedia has been known to be in error, take a look at https://en.wikipedia.org/wiki/Lake_Lagunita (which I should have done before I asked my question :-). It says the lake was artificially filled until the "the late 1990s". I guess they could have been getting the water from somewhere else, but I can't imagine where. There was a fish ladder installed on the dam in the 1950s. https://news.stanford.edu/2019/02/27/sta...rsion-dam/ That doesn't prove it was functional at that point, but if it wasn't I would expect just making a big hole would have been the way to go.

In any case the 2017 lake would have been the local runoff, not any "intentional filling". The following is "interesting" in that regard.
https://www.quora.com/Why-is-Lake-Laguni...ger-filled This answer implies that as late as 2017 Stanford had at least the theoretical ability to fill the lake. The problem with the porous lake bottom supposedly goes back a long way. I have heard it was caused by plowing up the bottom of the lake to plant a victory garden during WWII. Have no idea if that is actually so.