Water storage has become a critical concern in the Caloosahatchee Watershed. The US Army Corps of Engineers conducted a comprehensive review of the Central and Southern Florida flood control project (USACOE, 1998) and determined that it is necessary to develop 160,000 ac-ft of water storage to meet urban, agricultural and environmental needs in future drought years. The South Florida Water Management District (SFWMD) Caloosahatchee Water Supply Planning group has estimated the water supply requirements as being much greater. To meet these needs it will be necessary to construct surface water reservoirs to storage storm water runoff. The USACOE has proposed 20,000 ac in reservoirs with water 8 foot deep. Alternatives include development of several smaller reservoirs and the use of agriculture impoundments to meet the water storage requirements.

It may be possible to use agricultural impoundments to meet part of the water supply objectives. There are 40,000 ac of existing or permitted impoundments in the watershed. These impoundments are used for detention of storm water runoff. There is little hydrologic data available for these impoundments. Without this data it is not possible to determine the impact of the alternative impoundment water management on agricultural water demands or the farm operations.

A field project was developed to collect information pertaining to the potential storage and retention of water in agricultural impoundments. Although designed for storm water detention the water holding capacities of agricultural impoundments have not been quantified. It is important to describe the water storage characteristics of the impoundments. These include the actual storage volume and particularly the dynamic storage volume that may be available for irrigation. This analysis includes evaluation of seepage and evapotranspiration and how these processes affect water storage. This information also will be useful for evaluating the impact of seepage and ET on larger reservoirs to be built in the watershed.

The field project was designed to provide field data for develop detailed water budgets for selected reservoirs and necessary data for calibration of a hydrologic simulation model. The model, presented in next task report, will be used to evaluate alternative on-farm water management strategies that may identify better impoundment management techniques that Collect data for hydrologic model simulation. Provide time series of rainfall, ET, inflow and outflow for calibrating a hydrologic simulation model.