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from an average of 7 to 11 feet. The inshore zones exhibited depths of one to two feet over large horizontal distances, and in many areas stands of last year's annual weed crop extended above the water surface (Figure 4.7-3). Lake water levels remained high throughout mid and late spring after the winter rains ceased. By early June 1992 lake levels had receded only a few feet. Increased evaporation occurred during the warm periods of late June and July, and by mid-summer the surface areas of the lakes were reduced to about one-half of their original extent. At the termination of the field work in late August 1992 the water area was reduced to the middle portion of the cross sectional area of each lake basin and had a surface area of about one-fourth of that present in late winter. However, this remaining aquatic zone still averaged four feet in depth and extended nearly the entire length of South Tracy Lake (Figure 4.7-4). In the north lake it was confined to the southern portion of the lake basin. By late summer a dense annual weed crop had once again occupied the shallow portions of the now dry lake basins (Figure 4.7-5). However,unless the onset of the fall-winter rainy season is exceptionally late this year, it appears that an aquatic zone will persist throughout 1992 and may once again be quite extensive by the new year. Given this natural, unmodified annual cycle for these old Central Valley aquatic habitats, the term "permanent wetland" rather than "seasonal wetland" seems far more appropriate in describing these lakes. Pond/Stream Habitats Two additional permanent wetland habitats, the "Beaver Pond" and the Mokelumne River, are situated on the southern edge of the project site (Figure 4.7-1). The Beaver Pond was formed by damming an arm of South Tracy Lake and is maintained by waste irrigation water from adjacent vineyards (Figure 4.7-6). It holds water throughout the year, even during extended drought periods. This statement is supported by several of the larger fish specimens netted in the fall, 1991,lake survey,which presumably have lived in the lake for a number of years. The lake supports a lush inshore aquatic vascular plant stand which extends out to a depth of approximately 4 feet. Maximum lake depth at several sounding points ranges between 6.5 and 8.5 feet. A sparse shoreline riparian vegetation, consisting primarily of scattered willows, persists under heavy cattle grazing. The Mokelumne River is one of the many Sierra foothill waterways whose present flow is controlled by water releases from foothill reservoirs. Water level and flow rate varied greatly during the 10-month study period (Figure 4.7-7). Much of the shoreline vegetation present in late summer is temporally covered by high flows during the rainy season, then reappears and rejuvenates during the following dry season. The Mokelumne River also helps to maintain the woodland riparian area by periodically overflowing its banks. While this occurs on a limited basis, nonetheless, such overflows are of a magnitude to help restock the Beaver Pond with fish such as what occurred during the 1986 flood. Its passage along the presently undisturbed riparian frontage of the project site provides viewers with one of the last glimpses of what the majority of foothill stream riparian zones once looked like in San Joaquin County. 3