Cisco Sonar

By Bryce Nielson,The Cisco Kid

By now, I suspect that many of you have seen the “haunting” picture, taken from the Space Station (NASA), of white sediments swirling in Bear Lake’s blue, water.  The description below the image said that the sediment probably came in from North Eden, Fish Haven and Swan creeks.

I have been fascinated by Bear Lake’s physical characteristics since 1967 when my USU limnology class came to take water samples.  At that time, Dr. Bill Helm, told us about currents in Bear lake and that were influenced by the earth’s rotation and the relationship of the moon, much like tides.  It sounded too far out for me to buy into at the time.  To further his arguments, he described how researchers would suspend glass tubes filled with liquid gelatin and suspend them at various depths and locations.  They would then retrieve them with the solidified gelatin inside and and

measure the degree variation for level to describe the effects of currents.  Unfortunately, none of that data was ever published and was lost with Bill’s death.  I learned a lot in that class about water densities in relation to temperature, thermal stratification, fall and spring overturns and a myriad of chemical compounds that are associated with water.  I finished college, went to work for Utah Fish and Game (now Wildlife Resources) and ended up at Bear Lake as a research fisheries biologist in 1974.  One thing that the old, classical, scientists taught me was instruments were fine but when it came to understanding the natural world around us, constant observation is the best tool you have.

Bear Lake currents have resided in a corner of my mind since then.  I would watch where boats and floats and other debris drifted to when they were lost on the lake.  Given enough time, most stuff ends up on North Eden.  Living up in Bridgerland, I would look down on the lake see the surface waters covered in different patterns and swirls.  I still had a nagging feeling that this was all a result of the wind.  I have spent a good majority of my life creel checking fishermen.  Lots of time it was on the ice.  Then as I saw things closer, I observed that ice fishermen’s lines didn’t always go straight down.  Many times it was difficult to keep a light lure on the bottom.  Along the east shore they were always drifting towards the north.  This evidence convinced me that currents were active under the ice, away from the winds influence.  I would be looking at Google Earth around Garden City and would notice current swirls off Gus Rich Point.  When I was exploring the “Rockpile” with an underwater camera, an area of gravel could be seen, that was clean of sediments, obviously swept off by currents.  It turns out to be an important spot for Bonneville cisco spawning.  “Weed Beds” which attract fishermen after cutthroat and whitefish, also catch millions of cisco eggs that are drifting in the water column away from spawning areas which provide food for other fish.  Even the elusive Bear Lake sculpin depends on lake currents to distribute their larval fish around the lake, away from the only spawning substrate on the east side.

When I saw sediment swirls from space, it all made sense to me.  What I was seeing was three current cells, rotating counter clockwise bringing up calcium carbonate, marl, from the lake.  Calcium carbonate particles are extremely small and take a long time to drift through the water column (why Bear Lake water is blue).  Cells in the shallow water were picking marl up off the bottom sediment. The sediment in the deep waters was probably coming up from the thermocline.  This time of year the lake is stratified which results in the thermocline concentrating marl in that layer of rapidly changing densities with depth.  If you remember, the moon was at its closest distance to the earth around that time, so one could surmise that the currents were especially well defined and active.  One thing for sure, is that they were not created by a sediment inflow from North Eden Creek which has extremely low flows during September.  With irrigation diversions on Swan and Fish Haven, not much water enters the lake and it is crystal clear.

Bear Lake is such a complicated but stable ecosystem.  It has been here for over 200,000 years and I suspect will be here after we are all gone.  I will never quit learning about Bear Lake, but some of her secrets may take a while to surface like they did in September 2016.