What Would It Take to Make Lake Merritt Swimmable?

This week’s Bay Curious podcast tackles a question from the 7-year-old daughter of KQED’s Judy Campbell. Her name is Violet. She visits Lake Merritt a lot and she wants to know:

What would it take to make Lake Merritt swimmable?

Today, Lake Merritt is known as the Crown Jewel of Oakland, but it used to be called by a different name: the Lake of 1,000 Smells. To figure how to make it a swimming lake, it’d be good to know how it became un-swimmable in the first place.

Before Lake Merritt Was A Lake

Once upon a time, tides from the bay flowed freely in and out of Lake Merritt. In fact, Lake Merritt wasn’t a lake at all, but a tidal marsh, a slough. Water from the surrounding creeks flowed into the slough. During high tide, salt water filled the area. At low tide, when the water rushed back to the ocean, it left behind shimmering mudflats.

In 1852, the city of Oakland was founded and its new residents took advantage of the tidal flow.

“Back then, putting sewage in Lake Merritt was somewhat reasonable … it flushed twice a day!” says Chris Read, museum docent and researcher of the Camron-Stanford House exhibition, “Slough, Cesspool, City Jewel: the Evolution of Lake Merritt.”

“Originally, the population was very small. In 1850, there were about 70 permanent residents. By 1860, there were about 1,500 residents,” says Read. “As the population grew, they continued to throw sewage into the slough.”

Around this time, Dr. Samuel Merritt, the 13th mayor of Oakland, began building homes near the marsh. “He thought the real estate would be better if the slough was instead a lake,” says Linda Nack, a Camron-Stanford House docent. A weir — a kind of barrier across a river — was built in 1869 to control tidal flow and create Merritt’s Lake.

“That led to problems. If you reduce the flow of water, oxygen is reduced and the water gets more polluted,” says Read.

The next year Lake Merritt was declared the first wildlife refuge in the country, although motivations were not purely conservational.

“Dr. Merritt had a big home along the lake and he had his window shot out by a hunter,” says Nack. “His neighbor’s cow was also killed by the hunters.”

Gradually, the duck poo began to build up and the water quality worsened.

“The lake did smell, but people tolerated it,” Nack says.

In 1897, swimming at Lake Merritt became illegal. Despite the ban, newspaper clippings from the time show a few sanctioned swim events even after it was outlawed.

Over the years, there have been various projects to improve the lake’s water quality. Human waste was diverted into sewer treatment systems and the lake was dredged a few times. However, smelly algae blooms, and trash and pollution issues plagued the lake throughout the 20th century.

By the 1960s, Lake Merritt had picked up its nickname: the Lake of a 1,000 Smells.

The Lake Merritt of Today

Lake Merritt is now a far cry from the poop swamp of yesteryear. Funds from Measure DD, passed in 2002, have been used to clean up the waterfront and restore the creek. This has increased the flow of water between Lake Merritt and the San Francisco Bay. Still, there’s a lot left to be done. The EPA has listed Lake Merritt as an impaired water body, citing low dissolved oxygen levels and trash.

“We have 62-plus storm drains that drain into Lake Merritt, and the urban runoff from 7 square miles. It’s a lot,” says James Robinson, co-director of the Lake Merritt Institute, who helps organize volunteers to pick up trash around the lake.

In drier summer months, volunteers can pull 560 pounds of trash from the lake. But during wetter months crews pull out much, much more. In December 2015, 3,220 pounds of trash were pulled from the lake, says Robinson.

Lake Merritt Institute volunteers find all kinds of debris in the lake. The oddest items? A probation anklet, a bowling ball, a gerbil in a casket and a bag full of jewelry.

More commonly, volunteers pick up plastic bags, food, cigarette butts, children’s toys, used condoms, bottles and furniture.

Oakland officials are currently working toward the goal of no visible trash in the lake by 2022.

But it’s more than just the visible trash that is harming the lake. Some of the worst pollutants are cleaning chemicals, pesticides, leaked gas and pet feces. Birds also poop directly into the lake and volunteers have even caught people using the lake as a toilet.

Part of the problem, though, is that even when people aren’t using the lake as a bathroom, their toilets can still cause sewage to end up in the water.

“Our sewer lines go to a treatment plant, but our pipes are old. And, as systems get overloaded and overwhelmed, they can have leaks or spills underground. And that could end up in Lake Merritt,” says Kristine Shaff, from the Oakland Public Works Department.

Fecal matter is the biggest public health concern stopping swimmers in Lake Merritt. Human feces spread disease, and in order for the lake to be designated for swimming, there can’t be more than a minuscule amount of fecal matter in the water.

Since the lake is not currently open for swimmers, water quality tests are not regularly required, but are taken during special circumstances. One bacteria test, ordered after a sewage break,  found that disease-causing pathogens were 20 times what is considered acceptable for swimming.

Even if testing were done more regularly, testing for feces is difficult. The lake is big and the water moves. A water sample collected next to Fairyland could be safe one minute, but five minutes later it could be bacteria-ridden.

While most of the water in the lake likely would not make you sick, there is a risk. And so far that’s a risk that the city, and most people, are not willing to take.

Into the Realm of the Theoretical

Shaff, from the Oakland Public Works Department, says there are no plans to create a swimming beach at Lake Merritt.

“There are six city swimming pools run by Oakland Parks and Recreation. One of them, the East Oakland Sports Center, is a fabulous swimming venue, so take your kids there right away,” she says.

So from here on, our Bay Curious answer becomes purely theoretical.

“To make it a swimming lake, we would have to close off all of the pipes that drain into the lake,” says Shaff. “Then we’d be tearing up all kinds of streets, so that’s not really feasible.”

The second option would be to chlorinate the lake, or at least part of it. A similar project was done at Cull Canyon in Castro Valley, where the park built a chlorinated swim lagoon.

But chlorine comes with its own environmental problems. While it kills bacteria, chlorine also kills other living things in the water. Lake Merritt is first and foremost a wildlife refuge, so chlorination wouldn’t fly.

The third option — and likely the most realistic — would be to build a few acres of wetlands.

“You can pump the water through a wetland and let the wetland remove the bacteria. In fact, you could clean it down to whatever level you want,” says Dr. Alex Horne, professor emeritus of ecological engineering at UC Berkeley. Horne has helped build wetlands around the world.

“It’s easy. You get wildlife; it can look good. People would want to live there, because it looks like little lakes and islands,” he says.

A small pilot wetland was built a few years ago, but failed due to lack of funding. Horne says a high-quality wetland might cost up to $75,000 an acre. Money would also be needed to pump the water, maintain the wetland, get regular water-quality tests and employ lifeguards.

All this being said, and despite the dangers, people do still end up swimming in the lake. Boats capsize and people fall in all the time.

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