LADWP updates preparations for ‘massive runoff’

LADWP press release

May 23, 2017 Update

The Los Angeles Department of Water and Power (LADWP) has taken active measures to prepare for the arrival of anticipated massive runoff water resulting from this year’s near record snowpack in the Eastern Sierra Nevada Mountains. Now that the runoff period has arrived, the focus for LADWP crews has shifted from preparing waterways and spreading basins to now handling the large runoff flows.

Efforts are underway for LADWP to harness one of the largest snowpack runoffs from the Eastern Sierra watershed in the over-100-year history of the Los Angeles Aqueduct. Up to 1 million acre feet (AF) of water – or about twice the amount of water Angelenos consume in one year – is expected to flow through the aqueduct system this spring and summer.

LADWP is doing everything possible to prepare for this year’s extremely high runoff.  This includes preparing, cleaning, and repairing water conveyance ditches, spreading basins, sand traps, and other facilities that are controlled by LADWP.

To maximize the beneficial use of runoff water to the fullest extent, LADWP is spreading water throughout the aqueduct system to replenish local groundwater aquifers. Current spreading is moderate and will increase as runoff occurs in larger quantities later this spring and summer. LADWP is lowering reservoirs to create more storage space for runoff water and is maximizing flows to  the City of Los Angeles with aqueduct water in place of purchased water and groundwater wherever possible.

LADWP is committed to public safety and is assisting with flood control activities in the Owens Valley.  LADWP is partnering with Inyo County, the Inyo Sheriff’s Department, City of Bishop Police Department, Cal-Trans, Southern California Edison and others, as a member of the Inyo County Interagency Emergency Preparation team.

Work to prepare for the anticipated high water flows began in late February. The efforts have been assisted by an Emergency Declaration from the Mayor of the City of Los Angeles to allow LADWP to take immediate steps to protect infrastructure along the aqueduct and on Owens Lake to aid in managing flood waters while also protecting public safety. Inyo County issued a similar declaration.

Water that exceeds what can be spread to recharge the Owens Valley aquifer and which does not make it into the LA Aqueduct system will end up on the Owens Lakebed, the natural terminus point for waters flowing down the Owens River. Once there, it will add to the existing 30 sq. miles of saline brine pools and is expected to cause significant flood damage to dust control infrastructure managed and constructed by LADWP over the past 17 years. These measures, spread over nearly 50 sq. miles of dried lake, have effectively reduced dust pollution in the area by 96 percent. Damage to these dust control areas may result in increased air pollution that could threaten the health of the public after the runoff evaporates in 12 to 18 months.

“The extreme snowpack in the Eastern Sierra mountains creates excessive runoff,” said Richard Harasick, LADWP Senior Assistant General Manager of Water. We are doing everything possible to protect the people, property, and LADWP infrastructure in the Owens Valley, while at the same time maximizing aqueduct water supply to the City of Los Angeles, and save as much of the water to recharge the Owens valley Aquifer for future use.  I believe the men and women of LADWP, in cooperation with other partners are uniquely qualified to meet this challenge.”

In order to keep the public informed of the steps being taken to manage runoff to the greatest extent possible and minimize the impact to dust control measures, LADWP will issue regular updates of its runoff management efforts.

Runoff Preparation Activities undertaken by LADWP as of May 18, 2017, include:

Water Spreading

  • Long Valley: 2,100 AF
  • Pleasant Valley Reservoir to Tinemaha Reservoir: 35,000 AF
  • Tinemaha Reservoir to Haiwee Reservoir: 17,000 AF
  • South of Haiwee Reservoir: 5,000 AF

Total Water Spread: 59,100 AF

Water Spreading Activities

Mono Basin to Bishop

  • Spreading in the Long Valley has just began off of Convict and McGee Creeks.

Bishop Area to Tinemaha Reservoir

Work to maintain existing spreading ponds and diversion structures primarily in the Laws/Five bridges area which are fed by the McNally Canals includes:

  • Reinforcing and maintaining pond berms to increase spreading capacity and durability. Installing replacement head walls, diversion pipes and culverts to provide greater flexibility during spreading operations (100% complete).
  • Maintaining structures and managing flows. Additional historic areas of spreading may/will be identified and improved as able.
  • Road maintenance adjacent to the McNally canals has been completed, allowing carrying capacity of the canals to be doubled.
  • The portions of the McNally Canals and the McNally extension east of Hwy 6 are running water near capacity for the dual purpose of irrigation and spreading.

Work on the primary canals, ditches and ponds in the Bishop area has been completed in preparation for runoff; maintenance and repairs will be continuous during runoff and includes:

  • Roads adjacent to the Bishop Creek Canal between Wye Road and Warm Springs Road have been repaired and diversion structures reinforced as needed to increase capacity and help prevent over-topping (90% complete).
  • Mowing of the Bishop Creek Canal and associated diversions has begun and will continue as needed throughout the summer.
  • Replacing two headwalls and diversion structures on the Bishop Creek Canal to increase spreading capacity (Now beginning).
  • Running of the Rawson and Ford Rawson Canals for the purpose of irrigation and spreading. Further maintenance is scheduled on both canals to increase capacity and spreading potential.
  • Both the Collins and A.O. Collins canals are ready to receive and spread water.

Round Valley area sand traps, measuring stations and diversions have been cleaned by hand crews and or equipment (Complete).

Work in the area will be ongoing throughout the runoff event to maintain these structures.

  • Equipment has been staged at the Pine Creek flume in preparation of high flows.

Big Pine area work is ongoing and includes:

  • Cleaning of the Baker Creek sand traps, diversion structures and ponds. Work is estimated to be complete within the next week.
  • Cleaning and mowing of the Big Pine Canal, which is running near capacity. Further maintenance will be needed throughout the summer to maintain capacity once aquatic growth begins to restrict flows.
  • Repairing and maintaining adjacent roads to prevent over-topping (75% complete).
  • Cleaning and marking of Tinemaha and Red Mountain Creek diversions. Currently a small amount of water is being diverted and spread across the fan. This area will be continuously staffed with equipment and personnel as flows increase.

Work has begun in Long Valley as creek flows are only beginning to increase and includes:

  • Diversion structures on Convict and McGee creeks are being utilized for water spreading and irrigation needs (flow varies).
  • Cleaning and repairing of Rock Creek sand trap and bypass intake at Toms Place (Complete).
  • Equipment is being staged near Lee Vining Creek, McGee Creek and Rock Creek (75% complete).

Tinemaha Reservoir through Haiwee Reservoir Complex

Replace and maintain spreading infrastructure constructed in 1969 that includes:

Black Rock Area:

  • Blackrock Ditch Diversions – ready for immediate use. Will require ongoing maintenance to ensure maximum water spreading and reliable operation.
  • Stevens Ditch – Cleaning and replacing culverts (95% complete). Planned work finished this week but will require ongoing maintenance.
  • Thibaut area maintenance (Complete). Will require ongoing maintenance.

Prepare the canals East of Owens River that includes:

  • McIver ditch from East of Goose Lake to south of Mazourka road.
  • Maintaining structures, replacing spreading pipes and reinforcing capacity in the ditch (90% of maintenance complete; scheduled for completion 5/26).
  • Eclipse/East Side ditch from Mazourka road to south of Owenyo area.
  •  Maintaining spreading areas and replacing culverts (100% complete). Will require ongoing maintenance.

Diversions on Alluvial Fans:

  • LADWP lands – 100% complete. Currently near max water spreading.
  • BLM and WSA areas – 100% complete. Currently near max water spreading.
  • Forest Service areas – 100% complete. Currently near max water spreading.

LORP Intake

  • Forebay – Seasonal habitat flow and preparation completed. Ongoing maintenance required.
  • Langeman gate and bypass pipe – Seasonal habitat flow and preparation completed.
  • Tailbay/Tailrace Channel Maintenance – Seasonal habitat flow and preparation completed.

Los Angeles Aqueduct

  • Intake – Maintaining water way capacity; will require ongoing maintenance.
  • Unlined section ­– Maintaining waterway capacity 80% complete; will require ongoing maintenance.
  • Lined section to Alabama Gates – Maintaining waterway capacity 100% complete; will require ongoing maintenance.

Owens Lake

  • Lower River Branch Diversion (Super Sacks, etc): 24.75% complete
  • Vegetation Tamping (Acres): 50% complete
  • LORPS (K-Rail, Sand Bags): 90% complete
  • LORPS Dike Expansion: 0% complete                               
  • T29 Berm Armoring (Rip Rap): 26.08% complete
  • T36 Berm Armoring (Rip Rap): 95% complete
  • Zonal Mainline Protection: 8% complete
  • Western HDPE Pipe Protection: 17.86% complete
  • Stream Clearing @ LORPS: 100% complete

Mojave to Los Angeles

  • Currently repairing/rebuilding Maclay Highline (35% complete)
 

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