[updated with an additional image of Barrett Dam]
After a nearly 7-year break in operations—with a brief restart in February this year only to be halted again—water from Morena Reservoir is again flowing toward the City of San Diego.
From Morena to San Diego
Morena Reservoir is located in East County about 45 miles from San Diego, near Campo. Water released from Morena flows down Hauser Canyon and into Barrett Reservoir (all photos can be clicked for enlargement).
Barrett is situated about 10 miles west of Morena, at the confluence of Cottonwood and Pine Valley creeks. Water is then released from Barrett and conveyed via the Dulzura Conduit to the Lower Otay Reservoir where it is treated and delivered to San Diego residents.
The Dulzura Conduit is a critical component making the whole system work.
The Dulzura Conduit is a 13-mile-long aqueduct beginning at Barrett, mostly concrete-lined but partly flumes, pipelines, and tunnels. Passing through remote and rugged terrain the Conduit diverts water west to Dulzura Creek leading to the Otay River. The water then flows through the river channel into the Lower Otay Reservoir.
Without the Dulzura Conduit serving as a diversion at Barrett, water released at the dam would otherwise continue down Cottonwood Creek which flows south into Mexico and joins the Tijuana River.
The Conduit was originally built in 1907-1909 by the Southern California Mountain Water Company under control of John D. Spreckels.
Rain and fire
The Conduit was renovated in the mid-1990s to replace the original wooden flumes and trestles with steel pipe on concrete and steel supports. Because of the remote location, helicopters were needed to support many aspects of the project.
In 2004-2005, however, heavy rains severely damaged the Conduit. Before repairs could be performed, the Harris Fire in 2007 caused further damage. Extensive repairs had to be planned, funded, and carried out.
The Conduit, with a capacity to move close to 40 million gallons per day, finally became operational beginning January 2011.
The Conduit came online just in time because that’s when Mayor Jerry Sanders ordered the Public Utilities Department (PUD) to absorb the 2012 rate increase for imported water purchased from the San Diego County Water Authority (SDCWA) instead of passing along the increase to San Diego ratepayers. PUD was to absorb the expense in part by drawing down local reservoirs (including Morena) so that less imported water would need to be purchased, and also by cutting staff and implementing “efficiencies.” In 2012, Sanders renewed ordered PUD to continue absorbing costs when SDCWA announced imported rate increases for 2013.
Morena drawdown encounters resistance
By 2013, enough water had been removed from Barrett that the City could start taking water from Morena. The original plan was to release about 20 million gallons per day from Morena to Barrett between February and June 2013. This was expected to save about $5 million in avoided imported water purchases. However, objections from the County of San Diego caused operations to halt in March 2013.
While the City owns the Morena dam, reservoir, and land around the reservoir, it has a lease agreement with the County which maintains the area for recreational purposes. The County said it felt that drawing down the reservoir would have negative consequences for recreational users, local residents, and the environment, and it requested that less water be taken. The ensuing controversy about this is documented in this East County Magazine story by Miriam Raftery and discussed further in this Reddit thread.
The City responded it was willing to limit the drawdown at Morena if the County would be willing to buy the water needed to keep the reservoir at the requested higher level, at a cost of about $1.7 million.
Receiving no further response from the County, the City resumed releasing water from Morena on December 1 (also noted by Fox5 San Diego). The drawdown is expected to continue for another 2 months or so until Morena’s level reaches 2,000 acre-feet.
Besides saving money for San Diego water customers, lowering the water level at Morena will facilitate a Capital Improvement Program project at the dam required by the California Division of Safety of Dams. As explained by Brent Eidson, PUD’s Deputy Director of External Affairs:
“Much of the mechanical equipment inside the existing outlet tower was installed in 1912 and has managed to operate well past its service life. In the interest of safety, the California Division of Safety of Dams (DSOD) is requiring the Department to renovate the outlet tower and add improvements to the dam.
As part of this CIP project, the top 23 feet of the outlet tower will be demolished and replaced with a new structure that will include a bridge extending to the top of the dam. All pipes, valves, ladders, and platforms inside the tower will be replaced. This project also includes a seismic stability evaluation of outlet tower and construction of a new parapet wall on top of the dam. The reservoir outlet pipe will be upsized to meet the DSOD emergency drawdown requirements. The estimated cost of this project will be in the range of $8 million. The project construction is scheduled to start in late 2014 and continue through 2017. The timing of this CIP project was set based upon City’s planned operation to lower the reservoir in order to reduce CIP-related costs.”
Although not a deciding factor, high reservoir evaporation at Morena was an additional consideration. Eidson says “It’s not so much that there is too much surface area, in total, but that the lake is relatively shallow (when compared to other lakes), so the combination of these, as well as the drier and hotter climate in the summer at this location is what leads to increased evaporation.“
Morena Reservoir for water supply versus Lake Morena for recreation
This isn’t the first time controversy has bubbled up over water withdrawals from Morena. This Los Angeles Times story describes an outcry over withdrawals that took place in 1989, with a similar outcome: the drawdown continued.
Part of the public relations problem, it seems to me, stems from the fact that large water releases from Morena are not a regular occurence. Once several years go by with relatively high and stable water levels, residents and recreational users come to expect it will stay that way. That creates a shock when it becomes necessary to withdraw water.
If the County were to agree to buy water to keep the reservoir level higher, it would likely require negotiating a rather detailed conditional agreement, since the main reason for the reservoir is, after all, to provide San Diego with a local source of drinking water (and as a bare minimum, an emergency supply). My guess is that the County prefers to avoid an expensive and complicated arrangement.
A very wet (but not TOO wet!) rainy season in the coming months would probably ease tensions all around.
Note about the photographs. I took the photos of Morena reservoir in July 2013, and the photos of the Dulzura Conduit on December 5, 2013 during a visit to Barrett Reservoir arranged through the Public Utilities Department with Brent Eidson’s assistance.