Lakes in the southern region of Minnesota went into the winter of 2018-2019 with very good fish populations. In particular, catchable walleye numbers in many shallow lakes ranging from 13-19 inches were still at all-time highs from successful walleye fry stocking during 2014-2017. We became a little concerned after a cold January increased the ice thickness and then snow piled up on lakes during February creating low oxygen levels on some lakes. After ice-out, we observed 15 lakes had partial winterkill and five lakes experienced a severe winterkill. Fish stocking plans for those basins were already established in DNR fisheries lake management plans and fish will be re-introduced as necessary this spring.