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project property, and discharging conditions exist in the lower portion of Elsmere Canyon

due to fracture avenues in San Gabriel Formation rocks and the hydraulic head difference
between this location and elevated ridge areas such as East Firebreak Road ridgeline.

Where fine-grained deposits may affected by the WCF, such as siltstone beds in Towsley
Formation, a clayey shear zone could develop along the fault plane which could locally

impede or slow rates of groundwater flow. This situation is observed where the WCF
crosses the Elsmere Canyon drainage at a high angle to groundwater flow direction, and the
canyon essentially has cut a notch through the fault plane. At this location, a clayey shear
zone has been locally developed along the fault surface between Eocene rocks and Towsley
Formation (see description of the Elsmere Canyon fault trench in Section 5.4.2 and Plate 5).
If this clayey zone extends at depth downward against faulted San Gabriel Formation, some

local "damming" effect along the fault plane could be possible. The damming effect could
be a contributing factor to the local presence of some springs and seeps that occur east of
the fault in the canyon bottom. However, there is no other direct evidence to support the
presence of a possible groundwater barrier along the fault plane, such as significant
differences in water levels in wells located on opposites of the fault. Where a clayey shear

may have developed along the fault in topographically higher areas, some damming effect
and local diversion of flow could occur, but the overall flow direction would still be expected
to approximately follow topography as shown in Plate 7A.

In summary, the degree of fracturing increases with proximity to the WCF, and the presence
and extent of fault gouge developed along the fault plane is likely a function of juxtaposed

rock type. Given these factors, groundwater flow likely follows through a locally complex
path in the vicinity of the fault, but may be expected to return to the general northwest flow
pattern controlled by topographic conditions and recharge-discharge areas. Under these
conditions, the WCF is not believed to significantly impede the overall groundwater flow or
substantially alter flow direction.

9.3 GROUNDWATER QUALITY

The following discussion and conclusions are based on hydrochernical data obtained at the
project property during three periods of groundwater and surface springs sampling and
analyses (Janes, 1991; Meredith/Boli & Associates, Inc., 1992a and 1992b). The testing

results of these three periods are relatively consistent within individual wells. Therefore,

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