Pinto Lake Restoration Efforts

Pinto Lake Water Quality Report Card

The Central Coast Regional Water Regional Water Quality Control Board issued the City of Watsonville the Pinto Lake Water Quality Report Card that they completed in October of 2018.

Pinto Lake Water Quality Report Card.

Decline of Pinto Lake Health

Pinto lake is one of only three natural resources in Watsonville that our community and area visitors can use for recreation. Pinto lake is an 8,000 year old lake and one of the few naturally formed lakes in the Monterey Bay. It is 100 acres wide at the surface and up to 27 feet deep in some locations. The lake is fed by the surrounding watershed which includes 4 creeks (Amesti, Todos Santos, CCC, and Pinto).
Equipment treating Pinto Lake with alum
Around 1980 an increase amount of harmful algae blooms started to appear in the lake indicating that the health of Pinto was declining. After extensive research, pollution of the lake was traced back to years of fertilizer runoff and leaky septic systems. Over the years, the bottom of the lake has been accumulating nutrients that feed the blue-green algae (cyanobacteria). This algae release dangerous toxins into the water, making the lake unsafe.

Restoration Partners

Who's helping Pinto Lake? The City of Watsonville, Santa Cruz County, the Resource Conservation District, neighboring communities and some cooperating farming businesses are working together to restore the lake.

Restoration Process

How will they help Pinto Lake? Cleaning up the lake will not be an easy task and multiple methods will be implemented over the next few years. Here are the first steps:
  1. Install sediment control practices near Amesti and CCC creek to prevent more watershed pollutants from entering the lake.
  2. Use Alum treatment to trap the nutrients embedded in the bottom of the lake that are feeding the algae. Alum is a substance that will be applied to the water where it will remain at the bottom of the lake and provide additional treatment for nutrients. Alum treatment will begin in 2017.
These treatments will not end the problem, but reduce it significantly. Ongoing monitoring of the lake will continue to measure changes in the quality of the water over time.

Alum Treatment of Pinto Lake Completed

HAB Aquatics Solutions completed the treatment process on April 10, 2017. You can view their daily documentation by clicking on the link below.


Where's the funding coming from?
In 2014, the City of Watsonville secured $750,000 in grant funding to treat the lake and to address the creeks that are carrying pollutants into the lake.

Lake Dangers

Is it dangerous to come into contact with the water? Yes, the toxins that the green-blue algae release are toxic. However, you can't tell if the water is toxic just by looking at it. The water may look clear or green. The levels are usually high in the summer and fall. The City and County have posted signs to prohibit contact with the water.

Pinto Lake Documents