We experienced a slight algae bloom this fall shortly after the lake de-stratified. Phosphorus that was trapped in the hypolimnion during summer was released into the surface water, which fed a mild cyanobacteria bloom. Microcystis was not widespread, and was actually worse near the dam since our powerhouse was pulling water towards the flume line. Just be aware there may be clumps of cyanobacteria near the shore or on the sediment as the water recedes.
You may also have noticed something else as the water starts to recede. This time of year you start to see what looks like slimy balls attached to docks, boatlifts, seawalls, or any other hard structure. Although they look like something otherworldly, these harmless bryozoan colonies () are common in lakes and streams and actually serve a valuable role in lake ecology. The structures consist of hundreds or thousands of individual zooids encased in a gelatinous matrix. The individual zooids take in water and filter out microscopic algae. Water is then ejected through a larger orifice located centrally in the colony. It has been shown that a one square meter colony of the marine bryozoan can filter over 48,000 gallons of water per day. I have not seen any of our freshwater bryozoans that large, but in aggregate I am sure we have at least that volume in our lake.
Our drawdown is progressing after a brief setback due to heavy rainfall over the weekend. With both generators operating we release approximately 155cfs from the lake. This rate decreases as the drawdown progresses since there is less pressure pushing water out the flume line. But it also corresponds with a decrease in lake surface area as canals and bays are de-watered so the drawdown rate will progress at the same rate. It looks like a dry week ahead so this means we should be at our target depth by November 1. We will be holding that depth using the small generator only, so if we get heavy rain like we did this weekend the lake level may bounce up a foot or so, but we will bring it back down as quickly as possible.
Drawdown this year is earlier than past years because we want to make sure we can refill with rain exclusively. We are heading into another La-Nina winter, which means stormy and cold weather with above average mountain snow. This should help us refill once we close everything down December 1.
The other big thing happening during drawdown is our office remodel project. We have begun de-constructing the marina in preparation for the addition of a second floor. We have our building permit in hand and will be making progress as quickly as possible in light of the short schedule we are on. As a consequence, our marina office is closed and we are in a temporary office at 129 Foothills. You can call in with our main office number and it rings to our new location so communication should be seamless. Of course, mobile phones and email work as well.