October 2009 - South Tahoe Public Utility District

Like Project No. 14 (page 11-81), project implementation for Project No. 15 is contingent upon
water quality and quantity in the Indian Creek Reservoir.
The Upper Dressler Ditch carries freshwater from Snowshoe Thompson No. 1 Ditch at Indian
Creek to Indian Creek Reservoir. Portions of the ditch are concrete lined, while other sections
consist of loosely consolidated earth. These earthen areas are prone to a high rate of leakage
and erosion. Lining or piping sections of this ditch can reduce sediment transport. This project
should be phased on a priority reach basis. The District completed in 2007 the conversion of
approximately 2,000 feet to piped conveyance. Problem sections are planned to be improved
first and the concrete sections may require replacement as they deteriorate in the future.
11.2.1 Project Description
Unlined sections of the Upper Dressler Ditch are planned to be piped in a 48” diameter pipeline
to promote conveyance and ditch stability. The general construction method for piping the
Upper Dressler ditch will be to place the pipeline in the existing ditch alignment and backfill and
compact.
Figure 11.1 (at the end of Section 11) depicts the reach of the Upper Dressler Ditch that has a
high seepage rate and should be the priority reach when this project is implemented.
11.2.2 Project Considerations
The sections in most need of repair are entirely within District owned lands; access exists along
the entire alignment. Other than the pipe material, suitable bedding and backfill material may be
the greatest construction cost.
A detailed condition assessment for the portions of the C-Line to be converted to freshwater
conveyance which is associated with Project No. 2 (page 9-63) is necessary before final
decisions are made regarding the Upper Dressler Ditch Conveyance Improvements.
The conceptual cost of the Upper Dressler Ditch Conveyance Improvements project is $2.5
million.
11.3 Project No. 16 - Indian Creek Treatment Wetlands
This project addresses the purpose and need statement:
PN-9. Ability to meet Indian Creek Reservoir water quality requirements is impaired and
the District needs to meet TMDL requirements for the Indian Creek Reservoir.
Project No. 16 is contingent upon the success of the District‟s current Hypolimnetic Oxygenation
System project. The TMDL on Indian Creek Reservoir sets a water quality standard for
phosphorus. Concerns exist that flushing more water through the reservoir will transfer the
elevated level of phosphorus to downstream systems, thereby impeding the water quality
objectives of the receiving water bodies. If the Hypolimnetic Oxygenation System project meets
TMDL goals the need for the Indian Creek Treatment Wetlands Project will be eliminated. If the
Hypolimnetic Oxygenation System project does not meet TMDL goals, then the District may be
faced with increasing flushing flows through the Indian Creek Reservoir. Project No. 16 could
be constructed as shown in Figure 11.2 (at the end of Section 11) to address the impacts of
increased flushing flows on downstream systems.
South Tahoe Public Utility District
Recycled Water Facilities Master Plan - October 2009 Page 11-83