Garcia Molla’s results suggest that traditional districts supported by state projects combined with ‘two-part tariff systems’ exhibit the lowest consumption levels. They also suggest that all districts using groundwater exclusively or in combination with surface water tend to consume more than those that rely exclusively on surface water resources, indicating perhaps unsustainable use. Rieu (2005) shows that, although demand in Charente is elastic, local authorities have established quotas to avoid the negative effects on farm income.