REPORT OF INVESTIGATIONs No. 41


area of these lakes and Swindle Swamp is about 5,000 acres at an elevation of 70 feet.
   The variances in the supply of water and the constant drain through the ground cause wide fluctuations in stages of The Deadening lakes. In 1950, as a result of flood waters, the lakes reached an elevation of about 70 feet. Due to the dry weather for a period of several years (fig. 4) some of the lakes were dry and others had receded to elevations as low as 40 feet by 1956. Above average rains in the late 1950's caused some of the lakes to recover to normal levels. Since 1960 lake levels have again receded.
   The Deadening lakes have a considerable recreation potential. However, the wide ranges in lake levels prevent the potential from being realized.
   The Washington County Development Authority has proposed a plan to divert water from Econfina Creek to these lakes at the rate necessary to stabilize them at an elevation of 70 feet above mean sea level. The diversion from Econfina Creek would be at a point just downstream from Tenmile Creek, by way of a diversion canal to Porter Lake. After Porter Lake is filled, water would overflow through Swindle Swomp and Black Slouth to The Deadening lakes.

             GEOLOGIC AND HYDROLOGIC SETTING
   The Deadening lakes are located in the sinks and lake physiographic division (fig. 2). They originated by the collapse of the overlying sands and clays into cavities caused by solution of the limestone of the Floridan aquifer. Where solution and collapse activity has breached the confining layer, figure 22, there is a loss of water from the lakes to the Floridan aquifer.

                        WATER LEVELS
    Levels of the Deadening lakes have been as high as 70 feet and as low as about 40 feet above mean sea level. A topographic map made in 1950 shows an elevation of 70 feet for Porter Lake) and shows the Deadening lakes to be completely covered with water at an elevation of 69 feet. Based on flood marks, about 70 feet is the highest elevation that the lakes have reached. The bottoms of Hammock Lake and Porter Lake are at an elevation of about 40 feet. Hammock Lake was reported to have been dry in 1956.
    Figure 23 shows that lake levels have varied from a high of 68.3 feet in Porter Lake to a low of 44.2 feet in Gully Pond during the period frow 1961 to 1963. Lake levels declined throughout most of that period. In mid-1963 the lakes began responding to rainfall as