When it was found that settlers inexperienced with irrigation would not earn enough farm income from the water for several years, the repayment period was soon extended to 20 years and later to 40 years. Water prices charged to irrigators on reclamation projects were originally based on a cost recovery basis. So irrigation water was priced at its marginal cost of supplying the water. However the price of water was later changed from marginal cost to "ability to pay", based on the principle of repayment capacity.