The Contra Costa County Fire Protection District, the Contra Costa Water District and outside vendors are flooding several hundred acres of Delta peat soil in an attempt to finally extinguish a slow-burning blaze that started in late May, according to the fire district.

Smoke from the Marsh Fire, which started on May 28 in a Bay Point homeless encampment and has burned about 500 acres, has prompted the Bay Area Air Quality Management District to issue a series of air quality advisories for wildfire smoke in the eastern part of the county, the latest one released Friday extending the advisory through July 18. The smoke has been impacting the areas of Pittsburg, Antioch, Oakley and Brentwood.

The fire is now mostly burning peat, a spongy material formed by the partial decomposition of organic matter, usually plant material found in wetlands. Contra Costa Fire officials said peat fires are very difficult to extinguish, though this one is nearly out of fuel.

An explanation of how peat fires work. (Video courtesy of CNA Insider/YouTube)

Fire Capt. Steve Aubert said that flooding the area is “realistically the only way” to tackle a peat fire. He said they intend to pump between 10 to 20 million gallons of water over a 200-acre area.

“The water is starting to flow and we are working with the property owner to add additional pumps,” Aubert said Friday afternoon.

Aubert said that peat can go as deep as 6 feet below ground, so this is a big job and crews probably won’t see real results for a couple of days.

The BAAQMD air quality advisory is not a Spare the Air alert, the air district said, but people with sensitivities to smoke and other pollutants have been advised to take precautions such as staying indoors with the windows and doors closed and using re-circulated air in vehicles when driving.