I was talking to Dan Livdahl the other day and he asked if I remembered when we worked on part of the Lake Okabena survey more than 20 years ago. I told him I did remember, and when the subject came up it made me think back to those interesting days.
There was a water study started many years ago that actually sort of failed. The study was designed to examine all aspects of the watershed both upstream and downstream of Lake Okabena.
An important part of that study was to measure different chemicals and pollutants in those waters. This issue was (and you can tell this was a long time ago) that we were in a pretty severe drought and the stream flows were not substantial enough to get any measurements that would have been considered successful from a research perspective. The study stretched out for more than a few years and, finally, the desired data was collected.
I know that the study thing is kind of worn out for a lot of folks. They think we have done enough studies.
The issue today is that if you ever want to receive any funding from certain government agencies, you need to have a water management plan that is up to date and completed to a certain standard. This was the situation 20 years ago when this study was done.
One very cool aspect of the study that I was involved with was a sedimentation study and a baseline water depth recording.
We worked with Zieske Land Surveying. They had about 300 GPS coordinates that we recorded. We would drill a hole in the ice and lower a very long aluminum rod with a 12-inch disc on the end of it.
We lowered the rod down the hole until it came gently to rest on the bottom. We recorded that depth. We then took the disk off and sent the rod down the hole again.
The rod was about two inches square and 30 feet long. One end transitioned from square to round with a sharp tip. This section was about 10 feet of the overall 30 feet. We would drop the rod down the hole again, and then two adult males would try to climb it.
This pushed the rod aggressively down through the sediment on the bottom of the lake. It was an amazing change when the rod hit the original lake bottom.
The lake bottom, below all of the hundreds of years of sediment accumulation was sand and gravel. When the rod hit that original bottom, the vibrations caused by the rod hitting sand and rock instead of mud would travel up the rod and very easily be detected by the guys pushing on it. It was almost like the rod was charged with an electrical current.
There was no doubt when you contacted the original lake bed. We would then record this depth and compare it to the first reading. The difference was the depth of the sediment in that spot. We did this 300 hundred times over two days.
The weather was nice, but I can tell you that drilling 300 holes and climbing a rod 300 times wore this guy out. I was a lot younger back then, too.
The end result of that effort, at least back at that time, was the lake averaged 7.2 feet in depth. The original lake depth in some places was 32 feet deep. That is a lot of sediment.
It varied by location in the lake, but even with no human activity, a lake will slowly fill in due to natural causes.
If I remember right, the study findings figured that it took 30 years to add the last one foot of sediment to the lake.
The other finding that I was very impressed with was that they also figured that with newer farming practices, less tillage and vegetative buffers that the Okabena/Ocheda watershed incentivized, that under current conditions it would take 100 years to add the next one foot of sediment to the lake.
That should give all of us a bright outlook from a sediment perspective. The issues that many area lakes suffer from in our area is not that they are getting too shallow to utilize, but the water has so much phosphorus runoff that it stimulates strong algae growth and makes the water not much fun to recreate in.
All we can do is work together to help improve and maintain and protect our surface and subsurface water resources. They are not infinite.
Water issues should be at the top of everyone’s list. Add it to the top of yours.