Regular water quality testing at Woodlawn Lake may become the norm as recreational activities become more accessible there — but that’s not the case for the San Pedro Creek Culture Park, despite the fact that wading is allowed there.

Prior to this year, the San Antonio River Authority tested San Pedro Creek regularly. Those tests found bacteria levels were often high enough that the agency briefly closed the creek in 2018, as it found that some children were swimming rather than wading, increasing their risk of ingesting E. coli and other harmful bacteria.

River authority officials then spent $120,000 to, among other upgrades, make the wading areas shallower to discourage swimming. They also added warning signs.

Now, despite not collecting test data, river authority officials told the San Antonio Report that the area is safe enough for waders. Because of the shallower wading pools, the risk of ingesting water has been minimized, said Steve Graham, assistant general manager of the river authority.

“A lot of our sampling had to do with those early days where we had people recreating it in a way that we really never intended,” he said. “But we are very comfortable with what’s happening now.”

Water recreation opportunities are increasing in San Antonio, which Graham has said the river authority is “thrilled” about.

Woodlawn and Elmendorf lakes will soon offer kayak, canoe and paddleboard rentals. Paddlers are already allowed to bring their own gear to those lakes, plus parts of the San Antonio River, which also offers rentals.

Deceleration News, which offers environmental reporting and analysis through a social justice lens, first reported that the river authority stopped testing water in the creek.

What level of bacteria is safe?

Levels of E. coli are typically used as the testing standard, as its presence in water is a strong indicator of sewage or animal waste contamination. This is measured as “most probable number,” or MPN, which is a count of how many bacteria cells are likely to be in 100 milliliters of water.

Water should be 126 cells per 100 mL or less to safely swim in it, 206 cells per 100 mL or less to wade in it, and 630 cells per 100 mL or less to safely partake in paddle sports, according to the Texas Commission on Environmental Quality. This standard is based on how likely one is to ingest water while performing specific activities.

This chart from the San Antonio River Authority shows E. coli levels in San Pedro Creek in 2022. Primary contact recreation 1 is swimming, and 2 is wading; secondary contact recreation is paddling.

The river authority has long tested the water at Elmendorf Lake and said last month it could begin regular testing of the water at Woodlawn Lake.

Both bodies of water, like the San Antonio River and its tributaries, see elevated bacteria levels after rains. But the agency said it had no plans to post notices when bacteria levels are high.

Echoing what Graham told the San Antonio Report two weeks ago when discussing the water quality at Woodlawn and Elmendorf Lakes, Shaun Donovan, the river authority’s manager of environmental sciences, said that by recreating on any body of water, a person is taking an inherent risk.

“If there was this huge risk to people then we would certainly be responding differently or responding accordingly, but we know that the risk is low,” he said. “Daily sampling at a location is virtually unheard of in our world, even for the Texas beach watch program on the coast.”

On Friday, the air around San Pedro Creek Park’s wading pools reeked of the freshly laid fertilizer covering the flower beds along the park’s walkway.

No one was wading, despite the sunny weather. A snowy white Pekin duck and three male mallards glided through one of the pools. Algae covered the bottom like a shaggy green carpet.

But algae doesn’t correlate with bacteria levels. Formed as a result of nutrient buildup, it can be ugly and smelly, but it isn’t toxic to humans. Algae typically builds up when water flow levels are down — such as during periods of drought, Graham said.

“Algae is a natural part of the environment,” Donovan said. “We would never look at a water body and say, ‘Look, there’s algae — we need to do more water quality testing there.'”

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Lindsey Carnett

Lindsey Carnett covers the environment, science and utilities for the San Antonio Report.