Case Studies
In order to determine the effluent quality of  water around commercial greenhouses,  three case studies were undertaken to sample and monitor ponds and runoff drains from greenhouses that use recirculating and/or conventional cropping systems. The greenhouses were subjectively chosen to also include three unique catchment pond types: vegetated pond which had plants rooted in the littoral zone, a semi-vegetated pond which has less plants rooted in the littoral zone and a clear margin pond which had no plant material in or around the water. It is known from basic ecological studies that a well vegetated ecosystem with relatively high species diversity will withstand higher concentrations of inorganic salts and will actually "filter" the water that comes into contact with the vegetation (Odum, 1971). Algae ponds have long been used to stabilize waste material .
The purpose of this part of the study was to evaluate the quality of irrigation run off from typical commercial greenhouse production systems. This information was to help indicate potential problems in effluent quality such as ion imbalances or accumulations. Chloride salts were of specific interest. In addition, the subjectively chosen sites represented variable ecological situations into which the effluent was discharged. Some limited conclusions were sought related to the impact of surrounding vegetation or the water quality in catchment ponds.
Some research results