Selectmen on Monday approved a roughly 30 percent increase in local water rates. Under the new rate structure, customers of the municipal system will pay an average of $4.11 per 100 cubic feet of water, up from $3.13 per 100 cubic feet. The change is the result of two wells being taken out of service due to high iron and manganese content, prompting the town to import more expensive water from Marlborough and the Massachusetts Water Resources Authority to cover the shortfall. Hudson officials have said the new rates could be in effect for a year or more while improvements are made to the water system. Full story for BostonGlobe.com subscribers.