• perennial yield – maximum quantity of water that can be annually withdrawn from a groundwater basin over a long period of time (during which water supply conditions approximate average conditions) without developing an overdraft condition

Glossary of Water Terminology. (2015, August 13). Retrieved January 16, 2017, from http://www.worldatlas.com/h2oterms.htm

Here’s a link to learn a little more about what is going on here in Michigan with groundwater pumping.  http://www.mlive.com/news/index.ssf/2016/12/why_nestle_pays_next_to_nothin.html