Lake Roberts Hydrologic / Nutrient Budget

CPWG Environmental and Water Resources Team recently completed a nutrient/hydrologic budget and water quality treatment plan of Lake Roberts for Orange County. Lake Roberts is a 107-acre water body with a perimeter of 13,200-ft located approximately 10 miles northwest of downtown Orlando and just southwest of the City of Winter Garden.

The primary objective of this project is to quantify pollutant loadings to the lake and identify areas or opportunities where nutrient load reductions could be achieved to improve water quality within the lake. The purpose of this study was to analyze the sub-basins contributing to Lake Roberts and to evaluate alternative lake outfall designs to reduce the period of high water levels. Hydrologic and nutrient budgets were developed to identify significant pollution sources and to provide a ranking of watershed areas with respect to annual mass loadings and area loadings.

CPWG Environmental and Water Resource experts designed a 12-month field monitoring program to collect data on groundwater seepage, sediment characteristics, and significant inflows. This program included both dry and wet season conditions and was used to develop the hydrologic and nutrient budgets. The hydrologic budget included estimated inputs from precipitation, groundwater seepage, and stormwater runoff. The nutrient budget included inputs from bulk precipitation, groundwater seepage, internal recycling, and stormwater runoff.  The team also conducted a detailed evaluation of sediment characteristics in Lake Roberts which included physical and chemical characterization of surficial sediments and evaluation of internal phosphorus recycling.

After completing the study CPWG engineers developed a water quality management plan to identify specific projects and recommendations designed to maintain and improve water quality in Lake Roberts. The primary objective of the management options discussed in this section is to control and limit the introduction of phosphorus and nitrogen into Lake Roberts.  Phosphorus and nitrogen inputs into Lake Roberts occur through a wide variety of sources, including bulk precipitation, stormwater runoff, overland flow, groundwater seepage, and internal recycling. The recommendations included both structural and non-structural activities.  The proposed alternatives include the “no change” condition to determine the current flood stages, improving the conveyance to the west and reopening (reinstalling) the drain well. Many of the recommended management options had relatively low associated costs, such as developing ordinances, restricting lawn maintenance activities, public education campaigns, re-establishment of naturally vegetated shorelines, and restricting boating activities in shallow areas of the lake.  Each of the recommended management options had the potential to result in improvements in water quality characteristics in Lake Roberts