SACRAMENTO, Calif. — Passersby around McLeod Lake in the city of Stockton might think the watercolor looks reminiscent of a bloody scene from jaws, but Ellen Preece with the Department of Water Resources said the pinkish dye released by them is harmless, and performing an important task.
“We have a number of sensors that will be out in the water measuring the dye,” Preece said. “Then those results will feed into a hydrodynamic model so that we can better understand how water circulates in this area.”
Understanding water circulation, Preece said, is part of the bigger goal to better understand harmful algal blooms.
“It is prone to having these dense, nasty blooms, in a lot of different areas [of McLeod Lake],” Preece said. “And so if we can understand why those blooms are occurring in these hotspot locations and potentially how they’re impacting the downstream waters, it will potentially help us decide what mitigation measures we can use in the future.”
The lake indirectly feeds into the California Delta, the most important water source for the state, which also supplies drinking water to Southern California.
Latest data from the state show reports of harmful blooms across the state increased from 100 in 2016 to over 600 in 2021, the increase a worry said Preece.
“Harmful algal blooms can produce toxins that are harmful to pets and humans, and then they can also negatively impact aquatic life,” she said.
Preece said blooms are caused by increased nutrients in the water that can come from human and environmental sources, along with warmer temperatures.
The effects of climate change increasing the warmer months, an added worry said former deputy Secretary of Coasts and Oceans for the state and senior scientist with the Natural Resources Defense Council Mark Gold.
“We’re seeing record water temperatures in our streams and lakes, now, on a regular occurrence,” Gold said. “And one area that also is very climate related that I need to mention is high nutrient loads. When you have wildfire and then you have rains that hit the burned areas. You also have firefighting, the use of Phos-Chek [dropped from planes and helicopters], which is really high in phosphorus, which also can lead to increased algae blooms.”
There are still key questions Preece said researchers are trying to answer in terms of why some blooms are toxic and others are not, and how to predict blooms.
“That is the gold standard. Is if we could forecast these blooms,” Preece said.
And why she said studies will continue, hoping to strike that gold.