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CW DMAG Update - June 30, 2006 Low Inflow Protocol (LIP) Drought Indicators

The following are the Low Inflow Protocol (LIP) drought indicators as of the end of June 30, 2006, except for streamflow, which is as of July 2, 2006:

Storage Indicator (SI):
Storage Index = 74%
Target Storage Index = 75%
Ratio = 98.67% (Supports Stage 0)

Streamflow Indicator (six-month average versus historical six-month average):

Ratio = 59.6% (Supports Stage 2)

US Drought Monitor (three-month average):
Three-month Numeric Average= 1.67 (Supports Stage 1)

Since the C-W Basin was in a Stage 1 at the end of May, 2006, and all indicators have to recover to move back up to the lower Stage, the C-W basin is still solidly in a Stage 1.  The recent rains in June have served to refill some volume in the reservoirs and that is reflective of the storage indicator.  The streamflow indicator has lowered considerably from a month ago because the calculation has dropped a very wet December, 2005 from the rolling six-month actual calculation and added a slightly dry June.  Therefore, the six-month rolling calculation has a slightly dry January, very dry February, March, April, and June, and a slightly dry June.  The Drought monitor three-month rolling average contains the effects of the dry April and May.

As we have discussed, since we are operating under the existing license, the LIP is voluntary at this time.  However, Duke recommends that all adhere as best as possible to the provisions of the LIP.  As information, copied here are the Stage 1 actions of Public Water Supply Intakes.

Owners of Public Water Supply intakes and other intakes with a capacity greater than 100,000 gallons per day used for irrigation will complete the following activities within 14 days after the Stage 1 LIC declaration:

a. Notify their water customers of the low inflow condition through public outreach and communication efforts.

b. Request that their water customers implement voluntary water use restrictions, in accordance with their drought response plans, which may include:

  • Reduction of lawn and landscape irrigation to no more than two days per week (i.e. residential, multi-family, parks, streetscapes, schools, etc).
  • Reduction of residential vehicle washing.
  • At this level, the goal is to reduce water usage by approximately 3-5% from the amount that would otherwise be expected.  The baseline for this comparison will be generated by each entity and will be based on existing conditions (i.e. drought conditions).  For the purposes of determining ‘the amount that would otherwise be expected’, each entity may give consideration to one or more of the following:
  • Historical maximum daily, weekly, and monthly flows during drought conditions.
  • Increased customer base (e.g. population growth, service area expansion) since the historical flow comparison.
  • Changes in major water users (e.g. industrial shifts) since the historical flow comparison.
  • Climatic conditions for the comparison period.
  • Changes in water use since the historical flow comparison.
  • Other system specific considerations.
  • Provide a status update to the CW-DMAG on actual water withdrawal trends.  Discuss plans for moving to mandatory restrictions, if required.

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