I have to be missing something because I thought we had hit on that, but my thoughts are:
* Sago was "killed" off during cold winter
* Water levels increased prior to start of real sago growth
* Depth change impacted light penetration
* Surface runoff - including water, sediment, and lawn care products - "muddied" the water with a sort of nutrient soup
* These things all occurred at a time prior to the growth cycle for sago began
* algae was able to bloom in advance of the sago
* bloom eliminated clear water issue
* alage wasn't robbed of all its nutrients by sago and was able to maintain the bloom, blocking light for sago growth
Bingo!
When water is "muddied" during the spring, what part of the water column clarifies first? Top or bottom? I say the bottom as the heavier particulate will settle while the lighter/smaller stuff remains suspended for longer. closer to the surface is more subject to wave action from wind, currents, etc. and the particulate will remain suspended longer due to being agitated longer while the bottom is less affected by those things. Also, based on lots of scuba diving in mudholes over the years, it always seemed that at some point, often related to a thermocline in deep enough water, I would break through the really nasty stuff into better visibility.
