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Ecological Evaluation of Brovelli Woods P.C. Muick Hydrology Information on the hydrology of the parcel has been gathered from a ) Tom Zuckerman, a member of the Catwil Group and a lawyer specializing in water and toxics; b ) Robert Belt, Kjeldsen-Sinnock and Associates ; c ) the series of air photos ( 1940 , 1952 , 1963 , 1975 , 1983 ) from the San Joaquin County Department of Public Works (with assistance from Ms . Ericka Richert, Service Center Clerk) ; and d) San Joaquin County Flood Control Department. Copies of the air photo series are included in a map tube accompanying this report and another complete set was given to Bart Robertson, of the Catwil Group. The three most important facts about the hydrology of Brovelli Woods are 1 ) the property lies within the floodplain of the Mokelumne River, 2 ) a hardpan underlies under most of the property, and 3 ) since 1940 the ephemeral Tracy Lakes are rarely hydrologically related to the Mokelumne River except during extreme flood events (such as 1986 ) . Previous to 1929 the Mokelumne River was not dammed and the river flooded when flow exceeded capacity of the channel . In 1929 , the dam for the Pardee Reservoir was completed. The Pardee is owned by East Bay Municipal Utility District (EBMUD ) and provides domestic water to the communities of the east side of San Francisco Bay. Despite the dam, major floods occurred along the Mokelumne in 1955 and 1958 . In 1962 Comanche Reservoir was completed to contain more Mokelumne water and to reduce flooding along the River . Despite both dams, Brovelli Woods flooded in 1986 . Flooding Events Major floods occurred during 1955 and 1958 and the extent of the flooding was mapped by the San Joaquin County Flood Control Department. During both 1955 and 1958 the entire forest bordering the river was flooded . In 1955 flood waters backed up through the western edge of the property and inundated the land below the farm road which parallels Forest Lake Road. The flood waters also inundated a large tract of agricultural land south of the river. The 1958 flood resulted in less areal flooding around Brovelli Woods , and flood waters appeared to be largely confined to the areas immediately adjacent to the river channel with minimal flooding around the margins of the lakes. In 1986 the 50 year storm completely filled the lakes and the river overflowed its banks in some places . A levee, constructed before 1940 , extends from the property to the west more or less along Forest Lake Road for more than . 6 of a mile. Occasionally a small amount of water backs up behind this levee as in 1986 . According to the maps published by National Flood Insurance Program (NFIP, 1988 ) , all of the parcel along the river and adjacent to the lakes is in Zone A, the 100 year flood zone (Panel Number 060299 0130C revised July, 1988 ) . In general , the county flood control office only permits construction in the 100 year floodplain at elevations above the high water line, upon elevated foundations or building pads . In the case of Brovelli Woods this elevation is approximately 29 or 30 feet depending upon location. As I compared the air photos with flood maps it became clear that the closed canopy forest mirrored the areas of frequent flooding along the Mokelumne River. This raises interesting questions concerning the dynamic processes shaping and maintaining the forest vegetation. 4