Preliminary studies to pipe the Main Ditch that connects Forebay to Reservoir 1 Water Treatment Plant have been completed, but the lion’s share of studies remain.
An update on the project was presented to the El Dorado Irrigation District Board of Directors on March 24. Originally pegged for construction in 2018, it likely will be moved up to take advantage of state drought project funding.
The studies completed on the three-mile-long dirt ditch include an archeological inventory and survey, a botany study of wetland delineation, mapping of wells and septic systems near the Main Ditch and survey work on the actual gradient. Additionally, a red-legged frog assessment was done. There are 28 septic systems uphill from the Main Ditch.
An on-call engineer has been contracted to prepare a basis of design report that will include a hydraulic analysis, alternative alignment analyses, design criteria and estimated construction costs. That basis of design report is expected to be completed in three months, according to a report by EID engineer Bob Rice.
Some time-consuming actions remain for future board action, including environmental documents, right-of-way research and acquisition if a shorter route is chosen, public outreach and design detailed enough to go to bid for construction.
In 2012 the El Dorado County Water agency granted EID $40,000 and last year it granted $192,000 to advance the studies. This year on Jan. 13 the board agreed to submit a grant application to the U.S. Bureau of Reclamation for $1 million. If that is awarded the board would have to agree to match the $1 million with $1 million of its own money.
The value of piping the Main Ditch is four-fold:
1. It would save 1,200-1,300 acre-feet of water it loses each year through seepage and evaporation.
2. It would eliminate a vast majority of the 300,000 pounds of dirt and trash that the water treatment plant must eliminate and later dispose of.
3. It would eliminate fecal coliform that the ditch picks up from neighboring septic leach fields as well as oily road runoff.
4. The water saved could be transferred to El Dorado Hills to save on pumping costs from Folsom Lake or it could be used to generate an extra $300,000 in hydroelectric income.
In response to a question from Director Greg Prada, Water-Hydro Engineering Manager Cindy Megerdigian said the project would take two construction seasons to complete and thus could be constructed in two phases. The district will hear back from USBR in about two months regarding the grant, she said.
Construction is estimated to cost $3.87 million, though the engineering consultant’s basis of design will refine that figure. Total expense of the project ranges up to $5.1 million, Rice said.
The estimate of water loss from the ditch was made by Jones & Stokes in 1977. That year the state Department of Health wrote a letter saying there were compelling public health reasons for piping the ditch. The ditch conveys the district’s key water right of 15,080 acre-feet of water to the treatment plant.
“This section of our delivery system is an embarrassment, a huge embarrassment, a huge leak,” said Doug Leisz, president of Citizens for Water. “It is something that is an immediate concern.”
“There’s a lot of offset here,” said Director Dale Coco, noting that the solids coming into the water treatment plant add a lot of expense. “If we can prevent that, it decreases the cost of operations. Out third highest cost of operations is chemicals and supplies. It’s the only way to keep rates down.”
Coco also pointed out the $300,000 in annual power revenue that could be gained from eliminated ditch water losses.
“Sometimes you have to spend money to save money,” Coco said.