As wildfires raged through California this year, we learned – again – that water quality can be affected hundreds and maybe thousands of miles away from actual fires. As of December 22, more than 7,800 fires had been recorded in this state, covering nearly 260,000 acres. In November, raging Australia wildfires began and as of today they show no signs of containment. This puts an untold number of water sources at risk.

Sometimes even just a small fire-fighting effort shows us the potential for pollution that larger fires bring. In Berkeley, California along the San Francisco Bay last April, hundreds of fish were killed when fire-retardant foam used to prevent a gas-tank explosion on a garbage truck flowed into a small nearby stream. Almost ironically, the stream had been restored over the past few decades – at a cost of millions of state and local dollars – for fish and wildlife use.

Now consider the effects of fires and firefighting efforts at the scale we’re seeing across California and Australia. Because of climate change and land-use policies, these fires are creating new sources of air and water pollution as homes and businesses burn at the urban-wildland interface. As a water quality expert at Stanford recently explained, the impacts of these fires are not yet well understood or well researched, because these are relatively new circumstances.

Stanford University hydrologist Newsha Ajami, PhD, outlined in a new interview with Stanford News: “When wildfires reach urban areas, they burn houses, cars, restaurants and stores which are full of electronics, appliances, solar panels, industrial chemicals, batteries, paints and plastics, to name a few. If fire debris is not fully cleaned up, it can be flushed and transported into water bodies by rain.”

In addition, pollution can sink into ground water and be carried through the air. We don’t yet know what we’re dealing with, but we know it’s adversely affecting our water.