As downtown-based water infrastructure company Cadiz Inc. is well into the third decade of its pursuit of a massive water storage and transfer project in the Mojave Desert, it’s turning to a novel funding source: Native American tribes. In late November, Cadiz obtained a letter of intent from the Santa Rosa-based Lytton Rancheria of California Native American tribe to invest up to $50 million in the Cadiz project, also known as the Mojave Groundwater Bank. In an interview earlier this month, Cadiz Chief Executive Susan Kennedy said the company is now in talks with about a half-dozen other tribes. The aim, she said, is to obtain financial commitments from these tribes that, in combination with bond sales and other sources of financing, should cover the $800 million cost of the project.