Further information may be required if the responsible official determines that the information initially supplied is not reasonably adequate to fulfill the purposes for which it is required. An applicant may, at any time, voluntarily submit information beyond that required under these rules. An agency is allowed to require information from an applicant in the following areas:

(1) Environmental checklist. An applicant may be required to complete the environmental checklist in WAC 197-11-960 in connection with filing an application (see WAC 197-11-315). Additional information may be required at an applicant's expense, but not until after initial agency review of the checklist (WAC 197-11-315 and 197-11-335).

(2) Threshold determination. Any additional information required by an agency after its initial review of the checklist shall be limited to those elements on the checklist for which the lead agency has determined that information accessible to the agency is not reasonably sufficient to evaluate the environmental impacts of the proposal. The lead agency may require field investigations or research by the applicant reasonably related to determining a proposal's environmental impacts (WAC 197-11-335). An applicant may clarify or revise the checklist at any time prior to a threshold determination. Revision of a checklist after a threshold determination is issued shall be made under WAC 197-11-340 or 197-11-360.

(3) Environmental impact statements. The responsible official may require an applicant to provide relevant information that is not in the possession of the lead agency. Although an agency may include additional analysis not required under SEPA in an EIS (WAC 197-11-440(8), 197-11-448(4) and 197-11-640), the agency shall not require the applicant to furnish such information, under these rules. An applicant shall not be required to provide information requested of a consulted agency until the agency has responded or the time allowed for the consulted agency's response has elapsed, whichever is earlier. Preparation of an EIS by the applicant is in WAC 197-11-420.