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Summ Over the 1992 monitoring period, water levels have remained
relatively stable in six (approximately 20%) of the project property monitoring wells. Most
of these wells are located along topographically elevated ridges and areas surrounding the
lower drainage areas of Elsmere Canyon, such as Whitney Ridge, Cliff Face Ridge, Pico
Ridge, and the west-trending ridge north of Power Tower Hill and west of Elsmere Canyon
South (Plate 7A). This group includes MW-21, MW-19, MW-16, C-8 and shallow well 09

of well pair C-9/C-10 (deep well C-10 has been oil-fouled; see Section 9.3). Water levels
in C-16, completed within the Whitney Canyon fault zone (Plate 7A), also remained stable
during 1992 monitoring. Many of these ridge wells also demonstrated relatively stable
conditions during 1991 (Janes, 1991). These effects are indicative -of slow

recharge/discharge groundwater areas that function as local groundwater divides.

In summary, several conclusions can be made with respect to water level trends observed
in response to heavy precipitation of the 1991-1992 winter. First, recharge and discharge
occurring first along the drainage divide traversed by East Firebreak Road, indicates that
the area of this ridge is a significant recharge area at the property. Second, slope areas

below the main divide experienced later recharge occurring from one to four months after
the major precipitation event was over. The variable rates of later recharge occurring in the
monitoring wells at these areas may be attributed, in part, to variation in the fracture
network and location with respect to the main drainage divide. Third, some wells
experiencing slow continuous recharge for the duration of water level monitoring are

probably located in areas of lower hydraulic conductivity where the fracture network in the
San Gabriel Formation is not as extensively developed. Finally, stable water levels observed
in some wells are indicative of groundwater divide areas where recharge/discharge effects
occur slowly due to isolation. '

9.2.4 Reltinhi twnronwar wnh in nnF

As noted earlier, fracture density increases adjacent to the Whitney Canyon fault
(Section 9.1.2). Where medium and coarse-grained sedimentary deposits or crystalline
bedrock are involved, this effect would be expected to locally enhance hydraulic conductivity
of forrnational units in these areas and augment groundwater flow rates. However, there

is no evidence that suggests this effect, where locally developed, alters the groundwater flow
significantly from that depicted on Plates 7A and 7B. The available data indicate that
topography is a major controlling factor in the overall direction of groundwater flow at the

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