Praying For Rain In California
While the East Coast welcomed the New Year with feet of snow and an arctic vortex of cold, the West Coast continues to pray for rain. As of December 31st, the U.S. Drought Monitor categorized all of California as in a state of either severe or extreme drought [PDF]. For a state that averages 21.44 inches [PDF] of precipitation each year, between 11-30% of that amount (see map at right) fell in 2013. In Nevada City, the California headquarters for American Rivers, just 0.95 inches of precipitation fell in December, compared with the monthly average of 9.37 inches recorded over the last 120 years. And this is the wet season!
Winter sport enthusiasts lament the lack of snow in the Sierra, and their cries have implications beyond recreational fun. The First Snow Survey of 2014 [PDF], released January 3rd by the California Department of Water Resources, reports “more bare ground than snow” and urges water conservation “as a daily habit” in the face of a possible third straight dry year for the state. Most of California’s water supply begins as snowpack in the Sierra Nevada; westward flowing streams fill the major rivers of the Central Valley and hydrate metropolises like San Francisco and Los Angeles. Even if the snow starts falling, greater than average snowfalls will be needed to overcome water deficits from dry years’ past. Reservoirs across the state, which are largely fed by snowmelt, continue to operate below capacity. Folsom Lake, for example, a key reservoir on the American River which supplies Sacramento, San Francisco and Central Valley farms is currently filled to just 18% capacity.
And what does this mean for rivers?
The simple answer is lower than normal water flow and increased water temperature. But in the connected world of rivers, ecologies & society the effects of low flow and increased water temperature are broad reaching. Here are just a few examples:
- Low flows restrict fish habitat by decreasing the amount of physical water space available. This reduction in volume can cause stranding – cutting fish off from spawning grounds, food sources, and cooler upstream waters.
- Less water in rivers means less water in reservoirs which can affect municipal and commercial water supplies downstream.
- Low flows result in restrictions placed on downstream water uses such as withdrawals for crop irrigation, which can ultimately affect food prices across the U.S.
- Low flows impact on-river recreational activities: white-water rafting and kayaking become restricted with less water in rivers, and depleted reservoirs attract fewer visitors as water levels drop.
- Fish egg incubation occurs within a specific temperature range. Above this range, egg mortality is common. As the river levels drop, eggs can become exposed to air which further damages their chance of survival.
- Fisheries, which attract tourism revenue and provide recreational opportunities, can become depleted.
- Increases in water temperature can affect bacteria load and food supply for fish, with implication up the entire food chain.
So while media outlets continue to cover the extreme cold and snowy conditions on the East Coast, stays tuned to the dry conditions on the West Coast and keep your fingers crossed for precipitation!