We have observed a good correlation between the level of Lake Merced and the preceding 10-year average rainfall.  This reflects the long-terms relationships observed by hydrologists regarding the lake and factors that affect lake level such as cumulative rainfall and pumping from the Westside Basin aquifer.

Note that for many years, from the early sixties to the mid-eighties, the level of the lake and the observed average rainfall moved together fairly closely.  During the drought of the mid-nineties the declining lake level clearly reflects the reduction in rainfall.  Unfortunately, however, with the return to normal rainfall in the late nineties the lake has failed to respond, and remains at historical low levels.