Stockton’s McLeod Lake is looking pretty in pink this week. The splash of color is part of a study being conducted by the California Department of Water Resources, which is dumping pinkish dye into the water to figure out why the lake has become a hot spot for harmful algae. Hazardous algal blooms, which can be toxic to humans, pets and aquatic life, popped up in McLeod Lake in 2020 and 2022 but — curiously — not this year. So scientists are using the dye to record the flow of water, which they’re hoping will answer the question of why the algae spreads some years but not others. Crews started dumping the rhodamine dye into the water Monday and will complete the study by Friday, according to a news release.