An exclusion of land from any irrigation district shall not impair its existence, nor its rights, including those in its property or its obligations. The land excluded from an irrigation district shall not thereafter be entitled to receive water from the water rights or from the irrigation works and system of the district and shall not thereafter be entitled to any of the benefits of the district and shall be deemed to have fully relinquished all such rights and benefits to the district, provided, that lands retained for drainage purposes shall be entitled to the benefits of the drainage system of the district.