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~ Water & Sewer Authority of Cabarrus County VVSACC Water and Wastewater System Master Plan Safe Yield Update and Regional Drought Operations Kannapolis is determined by the 1950's drought. For Lakes Fisher and Concord, the drought of the late 1980's defines the 50~year safe yield. Generally, Lake Howell and Kannapolis Lake are affected by similar droughts and Lakes Fisher and Concord are affected by similar droughts, as shown in Table 3. The similarities are attributable to the ability to refill the lake based on drainage area or the lack of significant storage volume to capture the available inflow. These observations are described for each reservoir, and they provide information for development of the drought operations strategy. I?.3.1 Lako Howell. Lake Howell is affected by droughts of long duration and low to moderate inflow, similar to characteristics of the droughts of the 1920s and 1950s. Droughts of extremely iow inflow, but shorter duration, like the 1980's drought, do not affect Lake Howell greatly because of the large volume stored. The most recent drought exhibited long duration, from 1998 through 2002, and very low inflows. The ratio of Lake Howell's usable volume to its drainage area ratio is 112.7 million gallons/square mile. 2.3.2 Lake Fisher and Lake Concord. Lake Fisher and Lake Concord hold much less storage, and they do not respond well to very Iow inflows, even of short duration. The drought of the 1980's exhibited these characteristics. Over a longer duration, small storms may occur that refill the smaller storage volume. They both respond well to longer duration droughts of low to moderate inflow, like the 1920's and 1950's droughts. Their refill capabilities are due to larger drainage areas,, relative to their usable volumes. Their usable volume to drainage area ratios are similar.. Lake Fisher holds 40.1 million gallons for each square mile of drainage area, and Lake Concord holds 38.1 million gallons for each square mile of drainage area. £.3.$ Kannapolis Lake. Kannapolis Lake exhibits characteristics of both types of reservoir, due to its smaller volume, but greater refill capacity from Second Creek. Considering only the lake's watershed, Lake Kannapolis contains nearly 89 million gallons of usable volume per square mile of drainage area. If the Second Creek drainage area (55.6 mi2) was considered, then the refill capability increases dramatically. PN 096873.0800 1 7 ~-'~, January 23, 2004 BLACK & VEATCH ~1,~ .d~,I International Company