The Rancho Santa Fe Post

March Water News… From the Desk of Marlene E. King, Santa Fe Irrigation District Div. 3 Director

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February 16, 2017 Board of Directors Meeting… Lake Hodges overflow condition agreement: The Board voted unanimously to authorize G.M. Bardin to execute an agreement for the sale of Lake Hodges Water to the San Diego County Water Authority (SDCWA).

As was previously discussed in this column, S.F.I.D. and the San Dieguito Water District have been in discussions with the SDCWA to put in place agreements which, when Lake Hodges is approaching overflow conditions, could potentially sell S.F.I.D.’s and San Dieguito Water District’s “excess overflow” Hodges water to SDCWA. The agreement hammered out set the price at a 10% discount to the Metropolitan Water District’s Full Service Tier 1 rate, minus the cost to move the water to the SDCWA aqueduct. The Board agenda packet offered the following hypothetical price calculation: Purchase price = ($666/AF x 0.90) - $40/AF (cost to move Hodges water to Olivenhain Reservoir) - $140/AF (cost to move water from Olivenhain Reservoir to SDCWA aqueduct) - $50.60AF (Non-Coincident Demand charge) = $368.80/AF.

As was noted in a previous column, there are a lot of moving parts which must fall into alignment to allow water - which might otherwise spill from Lake Hodges - to be captured and sold. Lake Hodges has been owned by the City of San Diego since 1925. S.F.I.D. currently has storage rights to a maximum of 5550 AF of Lake Hodges water when the reservoir is at full capacity. In addition, S.F.I.D., along with San Dieguito Water District, has rights to receive 50% of the inflow into Lake Hodges. Lake Hodges has a total holding capacity of 30,000 AF, so those readers who are nimble with numbers quickly see that S.F.I.D.’s inflow rights are greater than our storage rights. The 2014 amended water rights agreement between the City of San Diego, S.F.I.D., and San Dieguito Water District will no doubt continue to be examined and possibly refined with improved hydrologic conditions.

Note: if and when conditions allow the sale of oveflow S.F.I.D. water to SDCWA, the public will continue to observe water spilling over the Lake Hodges spillway.

Some facts you might find of interest regarding the recent spillway failure at the Lake Oroville Dam: Lake Oroville rose nearly 50 feet in five days, overtopped its emergency spillway for the first time since construction was completed in 1969, which triggered the emergency evacuation of 188,000 residents. FERC has ordered a forensic analysis, and early handicappers are focusing on the incredible scouring power of “tiny bubbles”, or cavitation, with respect to the damage to the concrete spillway, and a re-evaluation of how the State of California Dept. of Water Resources measures how much water flows into the Sacramento River when the Sierra snow pack melts. From 1906 -1956 the data showed the river flow peaking in April. From the mid-1950’s - 2007, however, the Sierra snow pack melted earlier and river flow peaked in March. This earlier peaking is crucial: reservoir management is a process of carefully calculating expected incoming flows so that the lake can be lowered in anticipation of that calculated inflow.

The following link (scroll down and click onto “Days that Nearly Brought Disaster to the Oroville Dam”) provides a very good educational description of the Oroville incident on a day-by-day, lake level-by-lake level measurement, along with public agency advisories.

west.stanford.edu/news/blogs/and-the-west-blog/2017/oroville-dam-graphic

Finally, a brief chart of holding capacities of some prominent lakes might prove instructional:

Lake Hodges -      30,000 AF at full capacity 

Lake Oroville - 3,537,577 AF at full capacity

Lake Shasta -  4,552,000 AF at full capacity

Lake Powell - 24,322,000 AF at full capacity

Lake Mead* - 29,686,054 AF at full capacity (1935 capacity stated to be 32,359,274 AF, but recalculated in 2010.)

**Note: As the Colorado River Basin has been in a drought since 2000, the greatly improved volumes of water currently stored in California reservoirs allow California to rely less on our allocations from the Colorado River, thereby lessening the pressure that the Federal Bureau of Reclamation will insert itself into the process whereby Western States share the waters of the Colorado River.