Response of a soft water lake in North Florida, U. S. A., to increased chemical and particulate loading from its watershed

Summary

Phosphorus, inorganic nitrogen, chloride, silicon, and particulate matter input budgets for Lake Jackson, a 1515 ha closed basin lake in north Florida, U. S. A., have been constructed utilizing unit area loadings derived from three intensively studied, representative sub-watersheds; selected sampling of all streams entering the lake; and quantity and chemical composition of precipitation. Expanding urbanization in the southern portion of the lake drainage basin has resulted in degradation of water quality in a partially isolated arm of the lake; these changes include increased alkalinity (from 4 to over 50mg/l as CaC0³), increased specific conductance (from 27 to over 100 μmhos/ cm), increased phytoplankton production (from a average of 32 mg C/m³/hr to 147), increased molybdate reactive phosphorus concentrations (from 2 to 23 μg P/l), increased winter nitrate and ammonia concentrations, and highly increased sedimentation rates. The input budgets for P, N, Cl, Si, and particulate matter were constructed as a tool in delineating expected impact from urbanization in the remainder of the basin without stringent control efforts. These budgets were discussed in relation to existing water quality in the lake and expected water quality changes associated with continued, uncontrolled development in the watershed.