October 2009 - South Tahoe Public Utility District

Flow (MGD)
Section 5: Flow Projections - Recycled Water Quantity and
Quality
5.1 Recycled Water Quantity
The District‟s Wastewater Treatment Plant (WWTP) treats wastewater from the South Lake
Tahoe area of El Dorado County that is located south and east of Emerald Bay, including the
City of South Lake Tahoe (reference Figure 2.1 at the end of Section 2).
The District treats wastewater from commercial properties, single-family residences, and multifamily
residential dwellings for the purpose of this Master Plan. Only flow quantities since 1997
were deemed accurate because of errors in flow data before this time.
Figure 5.1 shows the daily average recycled water flows from May 1997 to January 2001. Data
through 2006 are available as annual averages only and are not shown in the figure below,
though these data were used in projecting future recycled water flows as discussed in the
following sections.
SOUTH TAHOE PUBLIC UTILITY DISTRICT
RECYCLED WATER MASTER PLAN
EFFLUENT FLOW
10
9
8
7
6
5
4
3
2
1
0
Mar-97 Sep-97 Apr-98 Nov-98 May-99 Dec-99 Jun-00 Jan-01
Figure 5.1: Recycled Water Flow versus Time 1997-2001
Natural variations in flow occur throughout the year. An analysis of the variation is necessary to
determine a peaking factor, which is useful when determining recycled water direct land
application needs. The 1998 and 1999 peak month occurred in early spring resulting from spring
runoff and the associated inflow and infiltration. A second peak also occurs in the summer of
South Tahoe Public Utility District
Recycled Water Facilities Master Plan - October 2009 Page 5-27