A local Biodiesel plant has reached a landmark. The Iowa Biodiesel Board says the Western Dubuque Biodiesel plant in Farley has produced its 500 millionth gallon since opening in 2007. The plant reached the milestone in October. The plant has 23 direct employees and 19 contract drivers and can produce up to 45 million gallons a year using soybean oil, according to the company. General Manager Tom Brooks estimated the plant contributed more than $145 million to Iowa’s economy through 2025, not including construction. The milestone comes as Iowa’s biodiesel tax credits are set to expire December 31, 2027. The Iowa Biodiesel Board is urging lawmakers to extend them during the upcoming legislative session. The board says eight biodiesel plants are operating in Iowa, with capacity to produce more than 400 million gallons a year.