Timing is everything
During all the rain we had in January, many people consoled themselves with the thought that California needs this rain and snow to fill our reservoirs. And given how low the water level in those reservoirs had been, the rain was indeed a blessing.
As with so many things, though, it all comes down to timing. Ideally, rain in the winter keeps the reservoirs in good shape through the spring, then snowmelt in the spring replenishes the reservoirs to get us through the summer and fall until the rains begin again. This requires rain at the right time, then snowmelt at the right time, or else you can end up with too much water in winter and spring or too little water in summer and fall.
A new study, described in Friday’s Los Angeles Times, has found that we have a timing problem — the balancing act we depend on to keep our water supply at manageable levels is no longer working out as well as it did when those reservoirs were built. The problem is that temperatures are rising, so snow is melting earlier than it used to. Instead of replenishing the reservoirs during late spring as mountain snow slowly melts, that water is flowing out of the mountains earlier, arriving in reservoirs when they are still flush with winter rain. As the Times story puts it:
But in California, reservoirs already operate on a delicate balance.
They are kept well below capacity during the winter as protection against flooding. After the rainy season, they are filled with the spring snowmelt, storing up water to be released during the dry summer months.
Heavier winter rains and earlier snowmelt are likely to overwhelm reservoirs, forcing an early release of water. That would leave too little water for the summer.
“The handwriting is on the wall,” said lead author Tim Barnett, a marine geophysicist at Scripps Institution of Oceanography in La Jolla. “Mother nature is going to stop being our water banker.”
Sometimes I wonder why I even read the news. Every day I discover a brand new way to worry about the future…


