Roy, brush piles are dumped in the lake at all levels.  It's a common practice to sink Christmas Trees/brush by dragging the trees on the ice(Which may not occur this year.), anchoring with cement blocks then allowing the brush to sink when the ice melts.   Most of these fish habitat are created by volunteers or anglers wishing to create their own private fish magnets.  
 
You should be able to find what appears to be brush piles on your fish finder, unfortunately traditional sonar does not give great detail when looking for such fish habitat.  However, should you find what is referred to as a 'blob' on the sonar and there is fish symbols appearing at the same time, it would be worth marking the spot.
 
Personally I would recommend, if you are not already, becoming familiar with the north end of the lake and work your way back from there.
"The stumps" is no secrete when it comes to catching fish, including walleye, in the spring time.
 
In the meantime, use the Navionics App as a GPS/Plotter to enhance your fishing enjoyment with the kids, until such time you have built your own fish catching logs.
 
If I could find the darn fish and catch em I'd have no problem in giving you the location(s) and, I wouldn't care a bit about "spot burning".
 
PS. Trade secrete: every time I get hung-up I mark the spot, I figure it's a brush pile and I mean to tell ya, looking at my log(s) there is a bunch of brush in that lake.  My lures and baits too!  
 
Tight lines and think Spring. 

Navionics app lets you mark way points.  Mark just about any brush pile you find, whether fish are on or not, as they might be some other time.  I'd turn off the "Share Data" in the settings, since you don't want everyone in WPA to know where you marked things...  Also, turn on the "Auto-Lock", so it doesn't go blank screen after 30 seconds of not touching your phone.  It's a great app.  Not as detailed as the chips that you can buy, but works great.  It shows creek channels and sunken road beds, which aren't always accurate, but gets you pretty close.  Just watch your depth finder drop, and throw a way point marker.  Once you get the hang of it, it will catch you more fish. 
 
I'd practice with it at home a bit.  I didn't and took me a good 10 minutes how to figure out marking way points on the water...  If you don't have a DC outlet on your boat, you will probably want to add one.  ~$10 for one at Wallyworld or Autozone, ect.  

  Finally got a Walleye boat today for mup there .   Hope I can get out a few times with my sons this yr. for Eyes & Panfish. Dang just got 'round 4000 BF ov rough cut for camp 
OwwE wHell there's always next yr. maybeE..
 
crappy