By July 1, 2007, a public utility that owns or operates a qualifying facility shall install, maintain, and operate continuous mercury emission-monitoring systems or other method of monitoring approved by the agency on each targeted unit and, where applicable, on each supplemental unit pursuant to section 216B.6851. The monitoring systems must use methods set forth in federal mercury regulations or such other methods as may be approved by the agency. The public utility shall report to the agency as public data the quality assured data produced from monitoring implemented pursuant to this section on a quarterly basis in a form prescribed by the agency. The data from at least six months’ monitoring must be used to establish a baseline for mercury emissions reductions under sections 216B.68 to 216B.688.