Progress for Pinto Lake water quality

The City of Watsonville is celebrating progress made towards a cleaner Pinto Lake.

Each year, the lake experienced toxic algae blooms which is harmful to the public. The cause of the blooms come from increased nutrients in lake sediments.

Pinto Lake has been closed during these blooms and boaters have been warned to avoid contact with the water.

It took extensive research to find out what was causing these toxic algae blooms to appear, and researchers found the blooms started all the way back in the 1980s.

At 8,000 years old, Pinto Lake is still a popular destination for people in the Central Coast.

“It’s pretty quiet, like there is people here sometimes but it’s nothing too crazy. It’s just the quaintness of it I guess,” said Nathaniel Lopez, who was fishing on Thursday at Pinto Lake.

Beneath the 100-acre-wide surface, however, phosphorus-rich sediment was feeding blue-green algae that is toxic.

“Phosphorus can be naturally occurring and we’re in a natural area where phosphorus is rich. It can also be caused from fertilizers, it can come from septic systems, it can come from soap,” said Watsonville Senior Utilities Engineer Jackie McCloud.

Getting exposed to toxic algae can cause skin rashes, liver damage and even brain damage in humans, but it can affect wildlife too.

“There were potential sea otter deaths that were associated with harmful algal blooms,” said McCloud. “We could connect the type of algae to freshwater systems and we knew Pinto was a source of that.”

In an effort to turn the lakes water quality around, the Pinto Lake Restoration Project was formed.

A $750,000 grant was provided to help implement strategies to reduce pollutants entering the lake.

The city used aluminum sulfate, similar to the antacid Maalox, to treat the water. The treatment successfully reduced the amount of nutrients in Pinto Lake by 91 percent.

There are still algal blooms in the water right now, but none of it has gone toxic.

Project Outcomes: Reduced harmful cyanobacteria-stimulating nutrients (blue-green algae) in Pinto Lake by using “nutrient trapping” strategies both within the actual lake and throughout the watershed, including connected tributaries. Engaged and educated the agricultural community and residents in the watershed on nutrient management practices. Coordinated with a Technical Advisory Committee to advise on and evaluate project activities. Applied treatment to Pinto Lake to decrease blue-green algae. Conducted 10 site assessments representing 305 acres. Designed, permitted, and implemented three sediment management projects at priority sites, and assisted four growers with
winter preparedness practices. Conducted six stakeholder events to educate and engage the community on strategies to improve water quality in PintoLake. Assessed project effectiveness, determined adaptive management strategies when necessary, and provided follow-up technical assistance where needed.

Full report on the Pinto Lake Restoration Project HERE.

As for that half-acre floating island that was seen in the lake in 2016, McCloud says it is now anchored to the side of the lake.

“We had a company come out who was well known at doing that. And they anchored it down for us, so that it can no longer cause damage or safety concerns because we couldn’t see past it really,” she said.

The treatment should protect the lake for another 10 years. Both Watsonville and Santa Cruz County will now keep looking into ways to stop nutrient-rich sediment from seeping into the lake.