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Bureau of Reclamation updates 2009 Central Valley Project water supply allocation

Posted by: Maven on March 20, 2009 at 3:58 pm

From the Bureau of Reclamation, this press release:

Today, the Bureau of Reclamation announced the March update to Water Year 2009 allocations for the Federal Central Valley Project. This water supply update is based on the March 1 runoff forecast from the California Department of Water Resources.

Reclamation prepared two forecasts: a conservative forecast with a 90-percent chance of having runoff greater than forecasted (90-percent probability of exceedence) and a median forecast with a 50-percent chance of having runoff greater than forecasted (50-percent probability of exceedence). In the 90-percent exceedence runoff forecast, the unimpaired water year inflow into Shasta Reservoir is about 3.18 million acre-feet. Shasta Reservoir unimpaired inflow is the criteria used to determine shortages to water right settlement contractors, including the Exchange Contractors, and refuges.

Reclamation traditionally expresses the monthly forecast as a percentage (see summary table) of the contract total for each of the contract categories. The official allocation is based on the 90-percent exceedence forecast.  The 50-percent exceedence forecast is provided for informational and planning purposes.

Mid-Pacific Region
Water Year 2009 Supply Forecast Update
March 20, 2009

Probability of
Exceedence
Forecasts

Sacramento Valley Index* (Percent of Average/Water Year Classification)

North of Delta
Allocation

South of Delta
Allocation

Ag

M&I

R

WR

Ag

M&I

R

WR

Dry Forecast (90%)

51% / Critical

5%

55%**

75%

75%

0%

50%**

75%

77%

Median Forecast (50%)

61% / Critical

15%

65%**

100%

100%

15%

65%**

100%

100%
Ag = Agriculture  M&I = Municipal & Industrial (supply based on historical deliveries)  R = Refuges  WR = Water Rights

*The Sacramento Valley Index is a calculated estimate of the unimpaired runoff from the Sacramento River and its major tributaries and is used to determine the water year type.

**The allocation percentage for M&I is approximate and may be adjusted to meet public health and safety needs.

The allocation for the Friant Division Contractors will be 65 percent Class 1 water and 0 percent Class 2 water based on the 90-percent exceedence forecast.

Reclamation continues to coordinate with the State of California, the U.S. Fish and Wildlife Service, the National Marine Fisheries Service, and other Federal, State, and local organizations to fulfill its water supply obligations, which include senior water rights, water quality, and the protection of fish and wildlife and associated habitats.

“Reclamation will continue to monitor runoff and reservoir storage conditions in the event changing conditions will support higher allocations,” stated Donald Glaser, Regional Director for the Mid-Pacific Region.  ”In the meantime, Reclamation will use all water management tools at our disposal to meet our obligation to deliver water responsibly.”

In the coming months, updates to this forecast will be announced as circumstances warrant.  Information will be posted on the Region’s website at http://www.usbr.gov/mp.  Please contact the Public Affairs Office at 916-978-5100 or e-mail ibr2mprpao@mp.usbr.gov for additional information.

Not sure exactly what that means? The Capital Press explains:

California farmers and ranchers will get some federal water after all – if they’re north of the Sacramento-San Joaquin River Delta.

The U.S. Bureau of Reclamation issued its updated allocation forecast on Friday, March 20, predicting that 5 percent to 15 percent of normal water deliveries would be available for agriculture north of the delta.

In the San Joaquin Valley, a zero-water scenario is still possible unless runoff levels reach 61 percent of average, at which point all Central Valley Project contractors would get 15 percent of what they would normally expect for agriculture.

North of the delta, urban areas would get 55 percent of their water under the dry forecast or 65 percent if the median runoff amount is reached – an achievement that the Bureau predicts has a 50 percent chance of coming true. South of the delta, residential areas would received 50 percent to 65 percent of their water.

Wildlife reserves and water rights holders everywhere would receive between 75 percent and 100 percent of their normal allocations, depending on the amount of runoff that accumulates this spring.

Read more from the Capital Press by clicking here.

March 20, 2009 · Filed Under Central Valley Project

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