low-income groups, usually for a moderate initial outlay. Yet interest rates for money borrowed for the initial purchase and for services are high. Moreover, given that such dwellings are illegal, constant bribes are required to prevent demolition by local authorities, and tenants face a similar threat for delinquency in payment to the landlord. 105 Corrupt civic agencies have allowed similar practices to govern the distribution of essential services. In Karachi, high demand for water along with rampant corruption and mismanagement in the Karachi Water Supply Board has created a "tanker mafia." Tankers obtain water from illegal hydrants or from poorer districts in the city and then sell it for profit. 106 The customers are often the inhabitants of the very districts from which the water was taken, and exorbitant prices force many to purchase the water on credit. 107 The results of such practices are increasing profit for entrepreneurs and local authorities and growing impoverishment of low-income urban dwellers. 108 Ecological Marginilization Resource capture often prompts a flight of dispossessed inhabitants from affected areas in search of a better life. Receiving areas - whether rural or urban - are frequently ecologically vulnerable and are further degraded as incoming migrants place additional stress on existing resources. According to the 1981 census, of the 5.92 million persons who had migrated within the country, 87.6 percent moved from rural to urban areas, while only 12.4 percent moved in the opposite direction. Over half permanently settled in cities. 109 The chief forces driving such