DEL DIOS -- The San Diego County Water Authority's progress in building a pipeline between Lake Hodges and Olivenhain Reservoir makes long-standing concerns about treating Hodges' sometimes green water more urgent, water officials said last week.

The idea of mixing Lake Hodges' sometimes green water with cleaner Olivenhain Reservoir water has posed treatment concerns to water officials for the last few years, but a theoretical problem is about to become a practical one.

Blasting for a 1.25-mile tunnel under Del Dios Highway finished last summer and the pipeline almost connects the man-made Hodges just south of Escondido and the reservoir over the hills to the west.

Construction of the underground pump station that will move Lake Hodges water has moved into high gear. Contractor Archer Western has been working double shifts to excavate the 120-foot hole that will contain the pump station and is scheduled to be finished next year.

"I think the water-quality issue has become imminent because pump storage is supposed to start in September 2008," said Kim Thorner, general manager of the Olivenhain Municipal Water District, last week.

The pipeline and pump station are part of the San Diego County Water Authority's Emergency Storage Project, designed to move water around the county in case of an emergency such as an earthquake.

The pump station is expected to add 40 megawatts to the region's peak power capacity, enough for 26,000 homes, Water Authority construction manager Jeremy Shepard said Tuesday.

It is also expected to make money -- $5 million per year, by some estimates -- by pumping water uphill at night when electricity is cheap and having it flow downhill to make electricity during the day.

But the Olivenhain water district, which includes parts of Encinitas, Carlsbad, Rancho Santa Fe and 4S Ranch, is objecting to allowing Hodges water to mix with the reservoir water it taps for its customers. District officials are discussing legal action to prevent it, according to a presentation by Thorner.

Lake Hodges contains levels of decaying organic matter and manganese that will foul Olivenhain water treatment equipment, the presentation says.

Rain washes sediment, oil and fertilizers from 250 square miles into the artificial lake, whose water level has fluctuated widely in the last few years.

A drought in the 1990s left the lake's waters low enough to allow willow trees to grow in shallow areas near Interstate 15, but the wet winter of 2004-05 flooded the trees.

Engineering studies say that upgrading Olivenhain's McCollum treatment plant to handle Hodges water could cost between $40 million and $60 million, Thorner said.

A joint committee of Water Authority member agencies has started work on an operations plan that will say when water can be moved in and out of Lake Hodges, Water Authority spokesman John Liarakos said Tuesday.

A draft plan is expected in November.

The operations plan will probably have "trigger points" for Hodges' water contaminant levels when the pipeline will need to be shut off, he said.

The operations plan will also say how much the level of Lake Hodges can be expected to rise and fall, but Liarakos said it will probably be less than a foot. Moreover, the pump station can be expected to be more active in the summer when the region's electricity demand is higher, he said.

Although the city of San Diego owns Lake Hodges and its dam, the city doesn't get any water from the lake. The Santa Fe Irrigation District gets about 30 percent of its water from Lake Hodges, which is treated at its R.E. Badger Filtration Plant.

State bond money could be available for either the Olivenhain district or the city of San Diego if an expensive technical fix is necessary.

Contact staff writer Quinn Eastman at (760) 740-5412 or qeastman@nctimes.com.

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Recent Hodges algae bloom

http://www.nctimes.com/articles/2006/12/09/news/inland/21_50_2212_8_06.txt