Section 35-11-1608 - No further action letters; findings; natural attenuation(a) If the department determines that no further remediation is required on a site, the department shall, upon request, provide the owner or prospective purchaser a no further action letter, subject to reopener or termination as provided in W.S. 35-11-1610. The department may only issue a no further action letter upon a finding by the department that the site does not require engineering or institutional controls or use restrictions to meet the standards specified in W.S. 35-11-1605(a)(ii).(b) When the department has determined that monitored natural attenuation over a reasonable period of time is appropriate and that no exposure to contaminated media is reasonably expected during the period of natural attenuation, the department shall, upon request, provide the owner or prospective purchaser a no further action letter. The no further action letter may require that the current use of the property continue during the period of natural attenuation and also may require that testing be conducted to confirm that standards are met.