Toxic Algae Plagues Watsonville's Pinto Lake

Sep 19, 2013

Blue green algae near the shore of Pinto Lake in Watsonville
Credit Krista Almanzan
Watsonville's Pinto Lake
Credit Krista Almanzan
Signs warn of the blue green algae at Watsonville's PInto Lake
Credit Krista Almanzan
Watsonville's Robert Ketley on Pinto Lake.
Credit Krista Almanzan

Watsonville needs to clean up Pinto Lake.   The popular recreation spot is plagued with toxic algae that not only smells bad, but can also make people sick.  To make matters worse,  the solutions are more expensive than this cash strapped city can afford.

On a peaceful weekday morning 20-year-old Juan Perez casts his fishing line out into Watsonville’s Pinto Lake.  “I come out here whenever I can,” said Perez.  Like many locals, Pinto Lake City Park has been a fixture in his life since childhood.  Some people grew up playing Little League on the nearby ball field, others fed the ducks and now bring their own kids to do the same. Perez has been fishing off this jetty since he was 8-years-old. “There’s a good amount of fish: bass, crape, blue gills,” said Perez.  Perez fishes for sport, catch and release.  Except last month, when he caught more than 100 pounds of Carp winning the $50 prize in Watsonville’s monthly Carpageddon competition.   At the city’s request, those fish did not go back into the lake.  Carp contribute to the lake’s problem with a toxic blue green algae called cyanobacteria.  The algae feeds on phosphorus, and the bottom feeding Carp stir up phosphorus in the lake.  "So if we can reduce the amount of Carp in the lake we can reduce the amount of phosphorus in the water column,” said Robert Ketley, Senior Utilities Engineer with the City of Watsonville. 

Walking out on the boat dock Ketley stops to point out the algae.  It’s green floating on the surface of the water, and then turns blue after it dries on shore.   The problem goes back decades, but has gotten worse in recent years. “The problem really manifests in the fall months.  That’s when you come down here and the lake will look luminescent green and will have an odor that you will either distinguish as gym bag or manure,” said Ketley.  He says the problem is worse in the rainy season.  That’s when the lake gets hit with runoff from nearby agricultural fields and from the homes that surround the lake.   So the City plans outreach.  He points to houses that line one side of the lake where they’ll be working with homeowners to address leaky septic systems.  “Whereas on this side we’ll probably focusing more, because they don’t have the septic systems, on landscaping. Do you really need to have that uber green lawn,” said Ketley.

But outreach and the Carpageddon competition will only go so far in addressing the blue green algae problem.  More solutions need to be researched including the potential of treating the lake with a chemical compound called alum.  “Alum is basically, for want of a better expression, one of the constituents of Maloxx.  What happens is when you put alum  into the lake it binds up the phosphorus, and you create a barrier on the bottom of the lake, over the sediment, so that the phosphorus from the sediments can’t get up in the water column,” said Ketley.  He says an alum treatment and further research will cost several hundred thousand dollars.  Money the city does not have.  Watsonville hasn’t recovered from the economic downturn when it had to cut staff and city services.  So Ketley applied for a grant from the State Water Resources Control Board.  He says the lake is the perfect laboratory lake for others to learn from.  “It’s not so small that any scientific work that’s done on it can’t be extrapolated out to other lakes and watershed, but it’s not so large that that scientific work becomes cost prohibitive to conduct,” said Ketley.

Back on shore, Patricia McQuade is eager for a solution.  She’s runs Pinto Lake Park for Watsonville, and has made changes because of the blue green algae.  First she no longer rents boats to family’s with kids.  “Can’t do that.  We can’t let them on the water because a kid has to put their hands over the side of the boat, right? Then they’re going to have to put their hands in their mouth,” said McQuade.  The algae produces a toxin that when touched or ingested can cause everything from nausea to liver damage, though no one has gotten sick yet.  In her office, McQuade pulls out a thick binder.  It’s filled with waivers signed by boaters before going out on the lake.  “which says right here, rashes, allergic reactions, exposure can result in serious illness or death at high levels,” said McQuade.

She recently helped start the group Friends of Pinto Lake.  It plans to keep this problem on the forefront of the community’s mind until there’s a solution that saves this ancient lake.  “When you think of how hard we work to save a redwood, maybe 300 years old.  Well this is 8000 years old, so we have to do it,” said McQuade.  It could be months before the City knows if it will receive the grant to try treating Pinto Lake.  In the meantime, the Carpageddon fishing competition continues.