"Correct name: Lake Helen.

Check Google Maps.

Lake Elmer Thomas is west of Medicine Park far away from Elmer Thomas Park.  
No matter how hard you find this to believe, the pond here is actually called Lake Helen according to longtime residents and all park signage.  Google Maps has it correct.

JJC5+H6 Lawton, Oklahoma, USA"
POI name: Lake Elmer Thomas
POI types: natural-water
OSM data version: 2020-05-14T01:25:26Z
 #mapsme