A 130-year-old paper mill in West Linn is back open, two years after its sudden closure. The newly formed Willamette Falls Paper Co. quietly restarted two months ago and is now trying out new classes of paper made from pulp and agricultural waste instead of wood. The mill said Monday it plans to begin commercial production of coated and uncoated papers by the middle of the month. The plant closed in October 2017, citing “unforeseeable events” that reduced available pulp for making paper. The shutdown cost 250 millworkers their jobs. Earlier this year, though, Clark County investor Ken Peterson took an interest in the site and made a “multimillion-dollar” investment to get the mill up and running again. Peterson’s investment firm, Columbia Ventures, has an eclectic portfolio that ranges from Texas real estate to augmented reality technology. He hopes to demonstrate the viability of using wheat farmers’ waste straw to make paper.