California Wildfires Highlight Threat to Drinking Water Quality

With California still reeling in the aftermath of devastating fires that forced thousands of residents to flee their homes and destroyed hundreds of thousands of acres of land, the threat is still not over. Now that the fires have been quelled, authorities are trying to deal with the impact on local drinking water sources and water supply systems.

Fires not only contaminate water sources with ash, silt and sediment, they also cause power outages that can affect water treatment plant's ability to treat water properly. This is exacerbated when water pressures drop as large volumes of water are used for fighting the fires. When mountain slopes are left bare after a fire, ash and sediment can be washed or blown into streams where it can clog up reservoirs, smother aquatic life and disrupt local water supplies.


The latest Californian fires demonstrate just how disruptive forest fires can be to local water supplies. According to a report in High Country News, long after the Californian blaze was extinguished, heavy rainstorms continued to wash silt and other debris downstream, causing disruptions to water treatment facilities that forced local water utilities to stop drawing water.

In forested watersheds — which provide nearly two-thirds of the West's water — trees, leaf litter and soil act as a sponge, soaking up rainfall and slowly releasing it to underground aquifers and waterways. Wildfires destroy that mechanism by baking the upper layers of soil, forming a compact, water-repellant layer, while at the same time burning plant roots that stabilize the soil. So when rain falls, instead of being absorbed by leaf litter, soil and roots, the water simply runs off, carrying sediment, debris and nutrients along with it, transporting them further downstream. This can result in devastating mudslides that can bury roads and destroy homes. It can also cause river beds, wetlands and reservoirs to become overloaded with silt, often requiring some form of intervention, such as dredging, to fix the problem. This silt and debris can make its way into water supplies, where it can compromise water quality.

While sediment in drinking water is primarily an aesthetic issue — i.e. murky water — smaller particles can also clog filters. Organic matter can also react with chemicals used in the water treatment process to produce harmful compounds such as chloroform. Spikes in nutrient levels can fuel algal blooms that can affect both the taste and smell of drinking water.

It is anticipated that huge fires such as these will occur more and more frequently in future, fueled by increasingly hot and dry conditions associated with climate change. While the onus rests on federal regulators and water managers to ensure that these events do not disrupt water services, you can take steps to ensure your family has access to safe drinking water should the authorities fail to do so. By investing in a good quality drinking water filter you will be able to filter out silt, sediment and potentially dangerous nutrients such as nitrates, as well as other common toxins, including bacteria. This will allow you to tap into practically any water source in the event that your water supply is disrupted.

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