5. Conclusions
Sugarcane farm fields to the south of the BBB were found to be the major sources of nutrients and total suspended sediments to surrounding waterways. A cost-effective mechanism to reduce these pollutants would be a series of breaks in the existing spoil banks along major drainage channels to allow water to flow into surrounding wetlands. Modeling results indicate implementation of a spoil bank interval:gap ratio of 500m:5m would increase N reduction from 21.4% to 29.2%, which is much lower than the theoretical 90e100% removal rate. One reason for this discrepancy is that dredging has deepened the main drainage canals to such a degree that even during severe storm events, water levels do not rise much above the surrounding wetland elevation, so only a very small fraction of the stormwater carried by channels is exposed to wetlands. Additional water quality management practices should be implemented at the farm field level, prior to water entering major drainage canals.