Vista Irrigation District (VID) owns and operated the Vista Flume and Siphon system, which is an 87-year old potable water transmission facility that transmits water from EVWFP to VID's service area. The flume and siphon system is a combination of gravity and pressurized facilities which extend for a distance of 11.25 miles from the EVWFP to the Pechstein Reservoir within a 50 foot wide VID right-of-way. The flume sections are 6.25 miles long and consist of 11 above-ground gunite bench sections and a quarter-mile long hard rock tunnel that flow by gravity. The siphon system is 5 miles long and is comprised of 9 steel and/or concrete pipe inverted siphons. This system is the sole means of delivering portable water to VID from the EVWFP and is the only transmission facility available to obtain water from VID's local supply at Lake Henshaw. Reconstruction and/or replacement of this system is required due to many factors including, age of structure, security, vulnerability and the increasing number of developments along its alignment. VID proposes to insert a High Density Polyethylene (HDPE) pipeline inside the majority of the 6.25 miles aboveground "bench" sections of the flame. Due to areas of tight horizontal curvature and/or access limitations, portions of the bench sections may require removal and placement with a new pipeline within the same alignment. Several siphon sections will also be line with cured-in-place pipe and/or an HDPE liner.
The Vista Flume begins at the Escondido/Vista Water Filtration Plant (EVWFP) in northeastern Escondido in San Diego County, and heads west for approximately 11.25 miles until its terminus at Pechstein Reservoir.
Notice of Exemption
Type, Section or Code
Class 1,2 Sec: 15301,15302
Reasons for Exemption
The Vista Flume and Siphon system is an existing facility. The proposed work involves reconstructing or replacing the interior (and portions of the exterior) of this facility. All reconstruction and replacement work to the flume and siphon are planned for the existing system; no new facilities are being proposed. There are no unusual circumstances envisioned for the project and construction-level issues will be addressed during design, with appropriate best management practices and/or additional feature incorporated to ensure no significant, short- or long-term disturbance to sensitive resources or habitats occur within the flume's area of effect.