Fire crews fought a brush blaze that broke out last Thursday afternoon along a stretch of Tomales Bay beach at Pelican Point, just north of Marshall Beach. Firefighters crossed the bay in a boat launched from Nick’s Cove while a Cal Fire fixed-wing tanker dumped a red cloud of retardant to halt the spread. The fire burned three-quarters of an acre, did not range close to any structures and was staunched by nightfall. The Point Reyes National Seashore is investigating the cause of the blaze, which ran near a beach north of which campers are allowed stay and accessible only by boat; no trails lead to the site. Chris Martinelli, a captain with the Marin County Fire Department, indicated that the fire was most likely human-caused. He thanked foggy, humid weather conditions for helping slow the fire to a crawl; during a drier time, it could have reached Seahaven and, in a worst-case scenario, possibly Mount Vision, he said. Since no roads led to the location, crews performed a lengthy boat launch from Nick’s Cove; it took an hour to unload portable water pumps from engines, load onto the boat and ferry across the bay. In the fire’s aftermath, some residents worried about the retardant’s impact on bayside vegetation and aquatic life. Cal Fire uses a blend of ammonium salts and water to cover plants with a non-flammable carbon coating that insulates and restricts air flow to any residual fuels, according to a report from the retardant’s manufacturer. While coated foliage may at first turn brown and wither, plants recover with rains and even flourish due to the salts, which serve as a primary source of nitrogen in many agricultural fertilizers, the report notes. Free ammonia present in the retardant can be toxic to aquatic life, however. Amy Head, a Cal Fire spokeswoman, said less than 50 gallons of retardant had entered the bay and that the state’s Regional Water Quality Control Board had been notified, according to protocol.