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The Big Creek Watershed

Consecutive dry years and unusually low snowpack in the mountains have produced especially poor run-off conditions, which are resulting in lower reservoir (lake) levels this year. There is still plenty to do in the Big Creek area.

Lake Levels: By the Numbers

Together, the major reservoirs at Big Creek together have a storage capacity of more than 560,000 acre-feet. These charts provide historical, present, and anticipated levels for each reservoir.

Anticipated Lake Levels:

Did You Know?

Big Creek provides habitat for wildlife, and recreational opportunities to thousands of visitors every year. Some interesting facts about Big Creek:

  • Big Creek was America's first large-scale integrated hydroelectric project.
  • Construction of the first powerhouse began in 1911.
  • Big Creek generates enough emission-free hydroelectricity to power 640,000 homes

Contact Info & Answers to Common Questions

For More Information, Contact Us

For more information about how the drought is impacting the Big Creek system, contact:

Cal Rossi
Local Public Affairs Region Manager
Calvin.Rossi@sce.com
(559) 685-3240

How much are lake levels expected to drop?

It is important to note that lake levels will fluctuate. In general, water levels at the six lakes in the Big Creek area are expected to be below normal this season due to a particularly severe drought. Anticipated lake level charts are available at on.sce.com/BigCreek2015.

Why is this drought different than previous droughts?

The impacts this year are compounded by this being the fourth consecutive year of below-average precipitation. Additionally in previous, less severe droughts SCE was able to store more water because downstream water users were able to get substitute water from other sources. This year all sources are severely limited. This means SCE need to allow more water to pass through the Big Creek system downstream earlier in the year, instead of storing it through the summer.

Why is there less runoff this year, even though we had rain and snow?

We have had some precipitation this year. Most of it was in the form of rain, instead of snow, like we usually receive in the Big Creek area. Additionally, a significant amount of the precipitation is being absorbed by the ground before it can become runoff due to how dry the ground is. These two factors are translating into less runoff later in the season like we normally have.

Why can’t SCE simply trap the existing runoff and allow lake levels to rise?

SCE’s contractual limits on when and how much water it may store in its reservoirs, those limits can become more restrictive in extreme drought years, especially when other water sources for downstream users are unavailable.

What will be the impacts to recreational use?

Recreational users should be prepared for low lake levels and variation in lake levels over the course of the season. It is possible that the recreation season for some lakes may be shortened due to lower than normal water levels. SCE will provide updates as available to the business community regarding lake levels.

When will lake levels be back to normal?

It is difficult to say with any certainty. Precipitation, in particular snowfall, is critically important to the health of the Big Creek system, both the hydroelectric production as well as for providing habitat for fish and wildlife and access for recreational users. The earliest lake levels could return to normal would be next year, assuming we do not have another drought year.

How come one lake is lower than another? Why do the lake levels fluctuate?

Water levels may vary between lakes, meaning some lakes might be lower than others. Water levels may also fluctuate over the course of the season, rising and falling multiple times. The path that water takes through the Big Creek system is complicated and can vary based upon the operating needs of the hydroelectric system and regulatory requirements. Additionally, some lakes have smaller catchment basins in which to collect runoff.

What am I supposed to do to make up for lost business/income?

Unfortunately, conditions outside of our control are having impacts statewide. SCE is providing this information to you early so that the business community can plan appropriately. We will provide updates regarding lake levels as available. We are looking for opportunities to partner with the local business community on this important issue which affects us all.

What will be the impacts to hydro electricity production?

Hydroelectricity production in the Big Creek system for 2015 is expected to be approximately 21% of normal.

What is the Shaver Pump Minimum?

This is the minimum amount of water needed to operate the Energy Storage Facility. The facility is used to store water at Balsam Meadows Forebay, pumped by low-cost electricity at night, and then used to power a hydroelectric facility during the day when the demand for electricity is greater. The total impact to lake levels is less than one inch. Due to the drought Shaver Lake will not be full enough to operate the facility in pump back mode this year.

When will SCE draw down Shaver Lake this year?

SCE is uncertain at this time if it will be necessary to draw down Shaver Lake in order to better support the statewide grid. Over half of the Big Creek system’s 1,000 Megawatt capacity is located downstream from Shaver Lake. If the California Independent System Operator asks SCE for the additional power, we will provide it. SCE will provide advanced notice if this becomes necessary.

Why is SCE drawing down Florence Lake?

SCE is performing maintenance on the dam liner for the Florence Lake Reservoir. As such, it is necessary for SCE to reduce the water level in Florence Lake for work to occur. Work is anticipated to start in June or July depending on permit issues and continue until late October. SCE will provide additional information as it becomes available.

Why can’t SCE divert more water from one lake into another?

SCE must follow regulatory requirements for operating its hydroelectric facilities. Additionally, there are physical limitations on the direction in which water can flow.

Why are lake levels in Shaver Lake not dropping as much as other lakes?

Safely providing reliable and affordable electricity to all our customers is our main priority. Maintaining Shaver Lake allows SCE to maximize its hydroelectric production, which in turn has impacts to the statewide electric grid. Normally SCE keeps Shaver Lake at 60% capacity or above to operate the pump back capability of Eastwood Powerhouse. Last October lake levels dropped below this level in order to meet required electricity production and contractual water deliveries. Due to the drought Shaver Lake will not be full enough to operate the facility in pump back mode this year.

Will there be any long term impacts to the fisheries due to the drought?

Although the reservoirs will be lower than normal this year, we do not anticipate any fish kills. Fisheries in this area are maintained by the California Department of Fish and Wildlife. Many of the fish in the area are supplied by hatcheries and do not reproduce in the lakes.

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