Any stationary source required by the district in which the source is located to install and operate a monitoring device shall retain the records from the device for not less than two years and, upon request, shall make the records available to the state board and the district. The district shall allow the source the option of using electronic or computer data storage, as defined in Section 40407.5 and consistent with Section 40440.3, as a method of record retention. The source shall not be limited solely to the installation or maintenance of strip chart recorders.