Lake warming is making eutrophic lakes harder to clean up. A study in Lake Chaohu, China, found that warmer temperatures are causing more fluctuations in nutrient levels, which could lead to longer-lasting algae blooms. The researchers used data from 2015-2016 and a computer model to show that internal nutrient cycling in the lake is a big factor in these changes. This means that efforts to reduce external nutrient inputs may not be enough to control algae blooms in the future. Water managers need to consider how climate change is affecting nutrient levels in lakes to better protect water quality.