LADWP preparing for ‘massive runoff’

LADWP press release

BISHOP, CA – The Los Angeles Department of Water and Power (LADWP) continues to work proactively to prepare for the arrival of anticipated massive runoff water resulting from this year’s near record snowpack in the Eastern Sierra Nevada Mountains. These efforts are in partnership with Inyo County, the Inyo Sheriff’s Department, 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 and aid in managing flood waters while also protecting public safety. Inyo County issued a similar declaration.

LADWP is concerned by the potential of water overflow in and around the towns and communities of the Eastern Sierra and is actively providing assistance in preventing and controlling runoff that could impact the public. Emergency assistance will be provided on lands throughout the valley should flooding threaten the property of a partner agency or the public.

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. The following is the first update to the runoff management activities undertaken to date.

Emergency Runoff Management Activities undertaken by LADWP as of May 4, 2017, include:

Water Spreading

Long Valley –                                                                                1100 AF

Pleasant Valley Reservoir to Tinemaha Reservoir –                   28000 AF

Tinemaha Reservoir to Haiwee Reservoir –                                9300 AF

South of Haiwee Reservoir –                                                       5000 AF

Total Water Spread                                                                    43,400 AF
Maintenance and Construction Activities

Mono County

  • Crowley Lake storage will be lowered to 80,000 AF to make room for anticipated runoff. Current storage – 89,000AF
  • Completed Long Valley Dam and spillway inspections (Work will be ongoing)

 Pleasant Valley Reservoir to Tinemaha Reservoir

  • Applied for variance from Department of Water Resources Division of Safety of Dams to raise Pleasant Valley Reservoir water level (Complete)

Work to repair and upgrade existing spreading ponds and diversion structures in the Laws/Five bridges area include:

  • Reinforce and increase size of pond berms to increase spreading capacity and durability. Installing additional head walls and diversion pipes and culverts to provide greater flexibility during spreading operations (95% complete)
  • Preparing to raise portions of patrol roads adjacent to the canals to provide additional free board and greater conveyance capacity in both the Upper and Lower McNally Canals. This work will provide the ability to spread over 100 cubic feet per second (cfs) into the nearby spreading ponds or to spreading areas located further downstream (80% complete)
  • Preparing portions of the McNally Canals East of Hwy 6 to accept water by mowing and cleaning (Complete)

Work on canals, ditches and ponds in the Bishop area include:

  • Cleaning the George Collins and the A.O. Collins Canals and repairing/replacing diversion and spreading structures (Complete)
  • Cleaning, mowing and repairing diversion structures on the Rawson Canal (Complete)
  • Cleaning, mowing and repairing diversion structures on the Ford Rawson Canal (Complete)
  • Cleaning and mowing Bishop Creek Canal (Complete)
  • Modifying irrigation ditches off Bishop Creek to maximize spreading potential (Complete – Additional work will be needed over the summer months to remove aquatic vegetation to maintain capacity in the canal)
  • Filling Farmers Ponds, located on the West side of Hwy 6, and installing new culvert and diversion structures to convey water to the ponds located on the East side of the highway (Complete)

Round Valley area work includes:

  • Hand crews cleaning all open diversions on Horton Creek and Lower Rock Creek (Complete – Work will be ongoing in the area with both equipment and hand crews cleaning ditches, installing culverts and diversion structures to maximize spreading potential.)
  • Cleaning the Rock Creek sand trap at Tom’s Place (Complete)
  • Installing a secondary headwall and culvert on the Mill Ditch at Round Valley Road to add capacity (Complete)

Big Pine area sand trap and diversion structure work includes:

  • Cleaning the Baker Creek sand traps, diversion structures and ponds (Complete
  • Cleaning and mowing the Big Pine Canal (Complete – Further work will be needed throughout the summer to maintain capacity once aquatic growth begins to restrict flows.)
  • Tinemaha Creek and Red Mountain Creek diversions cleaned and marked. (75% complete – Further work will be needed to direct flows into existing catch basins and spreading ponds located in the adjacent areas.)

Tinemaha Reservoir to Haiwee Reservoir

  • Repairing/rebuilding spreading basin infrastructure (85% complete – Able to spread in excess of 200 cubic feet per second at this time)

Work in the Black Rock Ditch area includes:

  • Rebuild/repair/replace culverts, check structures and distribution pipes (Complete)
  • Clean and/or repair distribution channels (95% complete)

Work in the Stevens Ditch area includes:

  • Mowing, cleaning and adding spreading culverts (Complete – Currently at 95% of capacity)
  • Prepare Thibaut area ditches and berms (Complete)

Work to prepare the two canals located east of the Owens River to divert imminent flow into the LORP experienced a small set back after the recent 300 cfs pulse flow down the Lower Owens River, it was discovered that the two canals needed additional work. This work includes:

  • Clearing McIver Ditch from East of Goose Lake to south of Mazourka Road (70% complete. Currently flowing 15 cfs during Owens River pulse flow. Evaluating additional work for maximum flows and spreading.)
  • Clearing the Eclipse/East Side Ditch from Mazourka Road to south of Owenyo area (90% complete – Currently flowing 13 cfs during Owens River pulse flow. Evaluating additional work for maximum flows and spreading.)

Los Angeles Aqueduct (LAA) work includes:

  • Cleaning the Unlined section of the LAA (80% complete – Cleaning will be needed throughout runoff season)
  • Cleaning the Lined section of the LAA to the Alabama Gates (100% complete – Cleaning will be ongoing as needed)

Work to prepare the Lower Owens River Project (LORP) intake includes:

  • Cleaning the Forebay (Complete – Will need to be cleaned throughout the year.)
  • Cleaning the measuring section (Complete)
  • Jetting the Langeman Gate area (Complete)
  • Cleaning the LORP tail bay and 100 Yards downstream (Complete)

Continually preparing the alluvial fan creek diversions west of the LORP:

  • LADWP lands:                                    100%complete
  • Bureau of Land Management areas: 100% complete
  • Forest Service areas.                                     100% complete

Owens Lake

  • Armoring of berms, northwest area Owens Lake (Work not yet commenced, in purchasing for contract award)
  • Construction of new trenches northwest area of Owens Lake (Complete)

  Lower Owens River Pump-back Station (Pump-back Station) work includes:

  • Placement of temporary barriers, gravels, sandbags and related components around the Pump-back Station to protect it from inundation (Waiting to receive approval from the respective agencies)
  • Widen the path of water within the Lower Owens River across from the Pump-back Station through creating a temporary channel allowing for greater conveyance of water. This temporary measure is intended to prevent ponding of the water in the vicinity of the Pump-back Station and decreasing the potential for water elevation rising in the vicinity of the Pump-back Station (Waiting to receive approval from the respective agencies)

Lower Owens River Temporary Flow Modification work includes:

  • Placement of temporary barriers and related components to redirect the water away from the Corridor 1 Road and the T36 DCA northern berm. This temporary measure is intended to prevent inundation and damage to the existing managed vegetation area in the T36 DCA (Waiting to receive approval from the respective agencies)
  • Modify the east bank of the Owens Lake Delta and tamp down the existing vegetation (tulles) along east side of the Owens Lake Delta to improve water conveyance capability and create a preferred pathway (Waiting to receive approval from the respective agencies)

Western High Density Polyethylene (HDPE) Pipeline work includes:

  • Temporarily securing in place about 825 feet of the irrigation supply lines from T36 dust control area (DCA) to T37 DCA. This measure is intended to prevent the existing three, 18-inch-diamater plastic pipelines from potential floatation and damage (Waiting to receive approval from the respective agencies)

Zonal Mainline work includes:

  • Placement of temporary plastic lining and related components to protect the Zonal Mainline from damage due to inundation and erosion of the slope of westerly berm road, the Brady Highway, from wave action due to high winds (Waiting to receive approval from the respective agencies)

South of Haiwee Reservoir

  • As of 4/30/17, LADWP has discharged a total of 4,300 from the Los Angeles Aqueduct at three locations: Rose Valley south of Haiwee Reservoir, Freeman Wash west of Ridgecrest, and Cameron Wash north of Mojave.
  • Working on reestablishing the Maclay Highline, which diverts LAA water to the Pacoima Spreading Grounds (25% complete)
  • Structuring the Power Plant One Slide Gate to place water into San Francisco Creek (Currently pursuing permits for this).

Equipment Staging

  • All requested heavy equipment has been rented and received based on forecast needs. Equipment is performing preparation tasks, will be staged during spreading and cleaning operations.

Safety Signage has been posted at the following locations:

o   Pleasant Valley Campground

o   Intersection of Pleasant Valley Dam Road and Chalk Bluffs Road

o   Intersection of Chalk Bluffs Road and 5 Bridges Road

o   The Four parking areas on 5 Bridges Road at the Bridge

o   The Four parking areas on Highway 6 Road at the Bridge

o   The Four parking areas on Line Street at the Bridge

o   The Road going to the parking area on Line Street at the Bridge

o   River Road Main entrances North and South of Line Street

o   All major recreation areas along the river between Line Street and Collins Road (ie The Ropes, Fishing holes)

o   River Road Main entrances North and South of Warm Springs Road

o   Big Pine Canal at Owens River

o   Collins Road at the “Hole”

o   Collins Road river access road

o   The Four parking areas on Highway 168 at the Bridge

o   River access Roads at Highway 168

o   End of Bartell Road

In addition to posting safety signage in public locations near swift flowing water, LADWP has also taken out advertisements in all local media advising the public to practice water safety during this period of high runoff.

LADWP encourages the public to practice general water safety throughout this period of high runoff. To obtain information on local floods or flood risks, residents are encouraged to sign up for CODE RED through the Inyo County Sheriff’s Office.

To report flooding please contact the Sheriff’s Office at 760-878-0383. Be prepared to tell the Sheriff’s Dispatcher the exact location of the flooding and if the water threatens structures, animals, land or roadways.

If water threatens human life, dial 9-1-1 immediately.

 

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