Abstract
This research evaluates changes in usage by single-family households to examine the impact of efforts to encourage reduction in water consumption during drought conditions in Collier County, southwest Florida, during a state-declared drought period in 2007-2008. The Collier County Utilities department promulgated lawn watering restrictions consistent with rules in place at the state level and the South Florida Water Management District. A program of publicity, outreach, and enforcement was implemented to enhance the restrictions' effectiveness at reducing residential water use. This research examines water use data on individual billing statements for selected samples of residences to quantify changes during the period of restrictions for four groups: households receiving targeted outreach; households where infractions were observed and fines levied; households in neighborhoods near those receiving fines; and households not subject to any of the above but subject to county-wide restrictions and receiving county-wide publicity. Aggregate and household results show that residents reduced usage in response to county-wide publicity and its supporting interventions. Two-population t-tests for each of the four interventions showed significant differences from the period before interventions to the period after (referred to as B/A period). The county-wide publicity sample detected significant reductions (p= 0.05 decision rule) in all three B/ A periods that ranged from between II% to 24%. The HOA outreach sample detected significant reductions (p= 0.05 decision rule) in two of three B/A periods that ranged from between 5.8% to 30%. The fines sample detected significant reductions (p= 0.05 decision rule) in all three B/A periods that ranged from between 14% to 33%. The nearby fines sample detected significant reductions (p= 0.05 decision rule) in all three B/A periods that ranged from between 9.3% to 30%. Analysis of proportions of the changes observed in the individual residences for before-after periods showed that most households reduced usage. The 30% or greater reduction category had between 24% to 42% of residences in the county-wide publicity sample, while it had between 18% to 38% of residences in the HOA outreach sample, and between 28% to 40% of residences in the fine sample and between 15% to 40% in the fine nearby samples. Surprisingly, these results also show that usage reductions achieved by the supporting interventions were not different from county-wide publicity usage reductions. ANOV A analysis of all interventions taken together (base vs. all supplements) showed that neither HOA outreach nor fines were different than county-wide publicity. Referencing the base with the supplements detected significant differences (p= 0.05 decision rule) in only B/A 1, where county-wide publicity reduced usage 11.2% more than HOA outreach, and 11.6% more than nearby fines. B/A 2 was the only period where the county-wide publicity sample had reductions in usage that were between 4.50% to 7.10% less than the fine and nearby sample but notably non-significant (p= 0.05 decision rule). Comparison of the proportions of the changes observed in the individual residences for the before-after period (base vs. all supplements) show that supplemental usage changes were surprisingly not distinctive from base usage changes. In the county-wide publicity sample between 38% to 71% of households reduced usage by 30% or more while between 33% to 42% of households increased usage by 30% or more. In the HOA outreach sample between 23% to 59% of households reduced usage by 30% or more while between 35% to 48% of households increased usage by 30% or more. In the fines sample between 40% to 70% of households reduced usage by 30% or more while between 31 to 43% of households increased usage by 30% or more. In the nearby fines sample between 23% to 66% of households reduced usage by 30% or more while between 30% to 47% increased usage by 30% or more. The accomplishments of this research provide the following important conclusions for future water shortage actions: First, county-wide publicity and supplemental outreach and enforcement have measureable changes in usage that can be evaluated. Second, consumer information in the form of county-wide publicity is reliable for changing usage, but the administrative process impacts the success of supplemental outreach and enforcement. Third, billed household usage has the advantage of being an evaluation tool that can discern intervention usage changes, success, and room for improvement however, careful consideration must be given to real world experimental control and data imprecision.
