Petaluma River Brims With ‘Fecal Bacteria’
By Will Carruthers
Nov 6, 2019
The river winding through downtown Petaluma might be the city’s single most defining feature. The city’s annual rivertown revival festival features views of the river and, farther south, recreationists use the water for entertainment and exercise every day.
Yet, since 1975, the state has designated the water a contaminated water body due to excessive levels of bacteria tied to fecal matter. The river has also been included on the list for excessive amounts of pesticides, trash and sediment at other times.
Now, a state water oversight board may pass a plan laying out the steps to lower the levels of bacteria in the river and its watershed.
At a Wednesday, Nov. 13 meeting in Oakland, the San Francisco bay regional water quality control board will consider approving an amendment to the board’s water quality control plan for the region, a document known as a basin plan. The proposed amendment will set a cap on the amount of fecal indicator bacteria in the river’s watershed—the TMDL—and identify actions required to reach that goal.
The federal clean water act requires the state to create the cap and cleanup plan, known as a total maximum daily load [TMDL].
Staff members working for the water board, one of nine similar regional bodies tasked with setting water quality rules in California, have been assembling the Petaluma river plan for several years, according to Farhad Ghodrati, an environmental scientist with the San Francisco bay board.
Although there are over 100 potentially dangerous bacteria related to fecal matter, scientists generally only test for a few varieties. These “fecal indicator bacteria,” including e. Coli, are a sign that animal waste has contaminated the water body. If those levels are above the bar set by the water quality control board, they add the water body to a list of “impaired” waterways.
“High fib levels indicate presence of pathogenic organisms that are found in warm-blooded animal (e.g., Human, cow, horse, dog, etc.) Waste and pose potential health risks to people who recreate in contaminated waters,” a report prepared by water board staff states.
The results of the Petaluma river tests weren’t good.
Multiple tests for traces of E. Coli between winter 2015 and summer 2016 across 16 testing stations in the watershed revealed levels far in excess of water board requirements.
For instance, water quality rules allow for the discovery of excessive levels of E. Coli in less than 10 percent of samples, but tests in the Petaluma river watershed showed excessive levels in 65 to 100 percent of samples in a series of six rounds of tests conducted over 18 months.
“This result shows that the magnitude of impairment in the river is pretty significant, and some of the highest concentrations we have seen in the region,” Ghodrati said about the E. Coli results.
While many strains of E. Coli are harmless, others can cause health problems, including diarrhea and vomiting, according to the centers for disease control and prevention.
If the water board passes the proposed amendment, san antonio creek, a creek running along the border between Sonoma and Marin counties, will also be added to the list of impaired water bodies for excessive levels of fecal bacteria.
“The testing we did as part of this TMDL development showed that the bacteria levels in all tributaries, including San Antonio creek, were well above the impairment threshold level,” Ghodrati, the state scientist, told the bohemian.
Because the Petaluma river has long been unhealthy, the news that state scientists have discovered excessive levels of bacteria, while concerning, was not all too surprising to one long-time river recreationist.
Susan Starbird, a coach for the river town racers, a kayak-racing group based in Petaluma, has been using the river since the 1980s.
While Starbird takes for granted that the urban rivers she uses around the bay area are somewhat contaminated, she still uses them with caution.
Although it is inevitable that kayak racers tip over in the river—”it’s part of the sport,” songbird says—she makes sure her students rinse off completely before leaving each day.
There are many potential sources for the excessive fecal indicator bacteria in the river. Agricultural uses and various human sources, including city and county sewer systems, private septic tanks, boats on the river and homeless encampments are among the sources named in the water board’s report. For each source, the water board recommends actions to reduce bacteria levels.
The water board has set a zero tolerance rule for human waste, because it presents the greatest risk to humans and is entirely preventable if one follows the proper procedures, according to the staff report.
“When operated properly and lawfully, sanitary sewer collection systems, [onsite wastewater treatment systems] and vessel Marinas are designed to not discharge any human waste to waters,” the report states.
One source of bacteria may be the two public sewer collection systems within the watershed: the Sonoma county water agency’s small but aging sewer collection system serving Penngrove; and Petaluma’s larger city collection system.
“Sewer line backups, overflows and leaks occur, frequently during periods of wet weather, creating a potential source of bacteria on land surface that may be transported via urban runoff to the nearby water bodies,” according to the staff report.
Because recent tests by water board staff detected “fecal bacteria of human origin” throughout the watershed, “discharges from the sanitary sewer collection systems [are] a likely source,” the report states.
The county’s Penngrove sewer collection system, which serves 1,300 customers compared to the 62,000 served by the Petaluma collection system, is has been disproportionately prone to overflowing leaking, according to the report.
Between 2007 and 2017, Petaluma’s system overflowed 77 times, while the county’s Penngrove station spilled over just 17 times.
However, despite being a fraction of the size of the Petaluma system and leaking far fewer times, the Penngrove system poured 534,331 gallons of sewage into the watershed over the 10-year period, compared to the roughly 818,475 gallons of overflow tied to the Petaluma collection system.
Overall, the Penngrove system’s mainlines were over four times more likely to overflow than the average public sewage system in the state, according to the water board’s report. The Petaluma system’s overflow rates for mainlines are below the state average.
Overflows are generally caused by “aging infrastructure that needs maintenance or replacement,” according to the water board report.
Sonoma water officials say that recent work on the Penngrove system – including redirecting some water into Petaluma’s system and cleaning the Penngrove system’s mainline – are expected to reduce the number of overflows at the Penngrove system.
Still, more repairs and upgrades are required, Pamela Jeane, an assistant general manager at the water agency, told the bohemian. Some, such as maintenance work, are in process. Others are planned.
For instance, Sonoma water plans to elevate the Penngrove pump station, which is located in a flood plain, so that the station can continue to operate during floods. The project will cost around $900,000 and be funded by local and FEMA dollars.
Onsite wastewater treatment systems (OWTS) within the watershed, such as septic tanks owned by homeowners in unincorporated areas, may also be a source of human fecal matter. Owners may have to make changes to their systems pending review by Sonoma or Marin county authorities.
Farming facilities with horses and cows within the watershed are another possible culprit. All told, there are approximately 16,000 grazed acres in the river’s watershed, and 149 grazing operations within the watershed which are larger than 50 acres. If those operations are not following water quality controls properly, animal waste may make its way into the rivers and creeks.
Water board staff will test the waters five years after passing the plan to give local governments and businesses time to fix potential problems, according to Ghodrati.
Once they have the results, the water board can revisit the Petaluma river’s listing on the list of impaired rivers. If the river is clean, they will remove it from the shit list.
[Editor’s note: This article previously referred to the city of Petaluma’s wastewater treatment facility as a potential source of contamination. The facility, which is used to treat raw sewage to a high level, is not a potential source, according to the water board’s staff report. The sanitary sewer collection system, the pipes which carry sewage from the city to the treatment facility, is a potential source. The article has been updated to reflect the distinction.]