Monomictic

Lakes and reservoirs which are relatively deep, do not freeze over during winter, and undergo a single stratification and mixing cycle during the year (usually in the fall).
Found on https://www.encyclo.co.uk/local/20094

monomictic

monomictic A reference to a lake having a single period of free circulation or overturn per year, with consequent disruption of the thermocline; it may be either cold monomictic or warm monomictic.
Found on http://www.wordinfo.info/words/index/info/view_unit/1309/
No exact match found