Protecting our drinking water depends on the protection of forests

rim fireIt should have been obvious to me that the health of the watershed from which our drinking water is sourced directly impacts the quality and quantity of what we receive. Clean and plentiful rainwater, snowpack and rivers down the line mean clean and plentiful drinking water in our towns and cities.

But the measure of a watershed’s condition is not its water alone, it is an entire ecological system that generates, collects, absorbs and protects that water. This means the safety of our drinking water is actually dependent on the health of an ecosystem’s vegetation. The more vulnerable the forests of a region, the more vulnerable the drinking water drawn from the watershed.

At home in San Francisco, CA, I am one of 845,602 residents using 37 million gallons of water per day (in 2014-2015), 85% of which is drawn 165 miles directly from the Tuolumne River Watershed via the Hetch Hetchy Reservoir in the Sierra Nevada Mountains.

 tuolumne river

In the first four months of 2016, the Hetch Hetchy Reservoir has been above its median level for the first time in several years.  According to the US Geological Survey, the Hetch Hetchy Reservoir hovered around 77% of capacity (279,000-276,000 acre ft) in the first week of May.

Still, the safety of our water remains precarious not just because of water levels at Hetch Hetchy but because of the impact of California’s long term drought on the forests that make up the Tuolumne Watershed. Executive Director of the Tuolumne River Trust, Patrick Koepele, explains that if politicians are unable to recognize the essential relationship between San Francisco’s drinking water and the forests of the Sierra Nevada and pass measures that protect and promote forest health, it is our drinking water that is at risk.

Devastating fire seasons pose a major threat to a watersheds like the Tuolumne. The Rim Fire which burned 260,000 acres around Hetch Hetchy in August 2013, damaging power houses and water distribution lines threatened to dump ash into the reservoir, impacting the 2.5 million Bay Area residents drawing water from it.

In a more recent example, below average rainfall over a three year period culminating in a rainy season only 65% of average in 2015 increased the vulnerability of the  Athabasca Watershed in Alberta Canada this month. The firestorm that erupted on May 3 has resulted not only in the displacement of thousands of residents around Fort McMurray but devastation for the watershed that supplies drinking water to over 150,000 people.

 fort mcmurray

Extended drought in California has led not only to tinderbox-like forest conditions, it has also put enough pressure on the ecosystem to change long-term relationships between organisms such as that between bark beetles and pine and fir trees. The trees, in years of normal rainfall are able to defend themselves against the pest’s attack by pushing them out with the sap they produce naturally. In a sustained drought, though, the trees don’t have enough moisture to produce the sap needed to combat the beetles. With the upper hand, the beetle’s attack kills the tree.

The more dead trees, the more fodder for forest fires. The more fire, the greater the threat to the reservoirs, dams and hydroelectric equipment that keep San Francisco humming.

Despite a good El Nino year, drought, climate change and overpopulation remain very real problems for the security of San Francisco’s water supply. Unfortunately, communicating the severity of these issues is easily undermined by directives such as the Executive Order issued by Governor Brown on May 9, 2016 that somewhat loosened restrictions on mandated water conservation, giving water districts the ability to adjust their emergency regulations through January 2017. According to the US Drought Monitor, California is still in “extreme drought” (one step down from last year where the state’s status was “exceptional drought) and relaxing conservation restrictions confuses the issue.

Focusing simply on water conservation also does not provide the protections necessary for the healthy forests that maintain a water supply. Until the public understands the importance of the watershed as a whole and values the health of the entire ecosystem that produces water for population centers, our drinking water supply will remain at risk.


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