October 2009 - South Tahoe Public Utility District

Table ES-2 presents vital numbers relative to the District‟s recycled water management, namely
the annual volume of recycled water the District must manage and the required acreage for
direct land application of the recycled water.
Table ES -2 Recycled Water Volumes and Application Acreage Requirements
Item 2007 2028
Harvey Place Reservoir Inflow (acre-feet annually) 4,873 6,498
Harvey Place Reservoir Outflow (acre-feet annually) 4,738 5,848
Application Acreage Required (acres) 1,458 1,799
Application Acreage Deficiency Based on Unblended Water (acres) 3 344
Application Acreage Deficiency Based on Blended Water (acres) 816 1,157
Table ES-2 Notes:
(1) The numbers presented are based on an assumed planning value recycled water
application rate of 3.25 acre-feet per acre per year.
(2) The numbers presented are based on actual irrigated acreage which is less then
Lahontan Regional Water Quality Control Board permitted acreage.
(3) The numbers presented do not include irrigation with recycled water on Diamond Valley
Ranch.
(4) The Harvey Place Reservoir outflow for the year 2028 is based on 10% reduction of
outflow with respect to inflow which is a 10 year average reduction factor.
(5) Values for blended water are based on the California week of the Nevada/California
rotation.
Table ES-2 is based on a year 2028 average daily flow of 5.8 MGD which is a result of flow
projection calculations presented in Section 5 (page 5-27). The estimated 2028 recycled water
volumes are conservative and are based upon increasing population. Compared to the 2007
value of 4.4 MGD this is roughly a 32% increase. While the District has seen a downward trend
in the amount of sewage treated at its wastewater treatment plant in the last three years there
are still over 2,300 parcels available for development based on TRPA‟s Individual Parcel
Evaluation Score (IPES) which may result in a population increase in the District‟s service
territory.
Analysis of Table ES-2 shows a current deficiency of 3 acres for direct land application of
recycled water based on unblended water volumes and 816 acres based on blended water
(Reference Table 13.1 through 13.3 for additional information). Blending of recycled water and
freshwater occurs on three contract irrigator ranches located on the west side of the West Fork
of the Carson River, and one ranch located on the east side. The combined, blended volume is
considered to be all recycled water and there may be issues with blended water flowing from
California into Nevada. Currently the contract irrigators have tailwater agreements with the
Nevada Division of Environmental Protection for recycled water entering Nevada. However the
situation could change and therefore the Master Plan includes projects which could help
alleviate the issue of blended water.
Further analysis of Table ES-2 indicates that the District should take action to address direct
land application acreage deficiencies. The application of recycled water on the Diamond Valley
Ranch presents the best opportunity for the District to establish additional application lands
while meeting a guiding principle of first using recycled water in Alpine County. Improvements
on the Diamond Valley Ranch will also address the regulatory concern of emergency temporary
storage of recycled water. The Master Plan presents the projects necessary to address these
and other issues.
South Tahoe Public Utility District
Recycled Water Facilities Master Plan - October 2009
Page xv