Low Water Levels at California’s Reservoirs

Low Water Levels at California's Reservoirs

(DailyDig.com) – The recent massive rains across the state have helped to alleviate the state’s severe drought during the last decade. Torrential downpours, heavy snow with power outages, flooding rivers, and powerful winds battered Northern California toward the end of 2022. Concerns about a dry winter have been alleviated by a strong helping of hydrologic optimism. The season has gotten off to a fast start, with additional snow and rain expected in early 2023. The prospect of restocking California’s ten biggest reservoirs this spring remains optimistic.

However, the recent wet and stormy weather will not relieve the drought, at least not soon, and it will not reverse the West’s driest stretch in 1,200 years. Much more rainfall is required to fully refill not just the surface reservoirs but also the groundwater storage.

“Our community can’t rely just on precipitation amounts or atmospheric moisture demand alone to understand how severe a drought is. We have to look underground to see how much water has been depleted from storage belowground in soils and rock. This is where the water that supplies streams and trees during [California’s] long dry season comes from,” said Daniella Rempe. She is a hydrologist and geomorphologist at UT Austin’s Jackson School of Geosciences.

Rempe earlier said that prolonged periods of insufficient rainfall not only deplete the hydration supply for plants but also reduce the quantity of groundwater stored in the landscape.

Groundwater supplies streams throughout California’s long, dry summers year-round. She explained that during drought, showers that would normally replace this groundwater would instead supply the dry root zone, slowing or stopping the underground water that feeds streams and reservoirs.

After a rainy start to 2023, reservoirs and groundwater levels may dry out again. Thus, dry years may leave tiny villages without water.

California might add reservoirs to brace for drought. In Northern California’s Sacramento Valley, Sites Reservoir will store 1.5 MAF off-stream water. The reservoir will be operational by 2030 once construction begins in mid-2024. Desalination facilities might also increase water supply by using salt water.

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