(a) Pre-development requirements. The authorized official shall fulfill the following requirements before developing an Assessment Plan.

(1) Coordination.

(i) If the authorized official's responsibility is shared with other natural resource trustees as a result of coexisting or contiguous natural resources or concurrent jurisdiction, the authorized official shall ensure that all other known affected natural resource trustees are notified that an Assessment Plan is being developed. This notification shall include the results of the Preassessment Screen Determination.

(ii) Authorized officials from different agencies or Indian tribes are encouraged to cooperate and coordinate any assessments that involve coexisting or contiguous natural resources or concurrent jurisdiction. They may arrange to divide responsibility for implementing the assessment in any manner that is agreed to by all of the affected natural resource trustees with the following conditions:

(A) A lead authorized official shall be designated to administer the assessment. The lead authorized official shall act as coordinator and contact regarding all aspects of the assessment and shall act as final arbitrator of disputes if consensus among the authorized officials cannot be reached regarding the development, implementation, or any other aspect of the Assessment Plan. The lead authorized official shall be designated by mutual agreement of all the natural resource trustees. If consensus cannot be reached as to the designation of the lead authorized official, the lead authorized official shall be designated in accordance with paragraphs (a)(1)(ii) (B), (C), or (D) of this section:

(B) When the natural resources being assessed are located on lands or waters subject to the administrative jurisdiction of a Federal agency, a designated official of the Federal agency shall act as the lead authorized official.

(C) When the natural resources being assessed, pursuant to section 126(d) of CERCLA, are located on lands or waters of an Indian tribe, an official designated by the Indian tribe shall act as the lead authorized official.

(D) For all other natural resources for which the State may assert trusteeship, a designated official of the State agency shall act as the lead authorized official.

(iii) If there is a reasonable basis for dividing the assessment, the natural resource trustee may act independently and pursue separate assessments, actions, or claims so long as the claims do not overlap. In these instances, the natural resource trustees shall coordinate their efforts, particularly those concerning the sharing of data and the development of the Assessment Plans.

(2) Identification and involvement of the potentially responsible party.

(i) If the lead agency under the NCP for response actions at the site has not identified potentially responsible parties, the authorized official shall make reasonable efforts to identify any potentially responsible parties.

(ii) In the event the number of potentially responsible parties is large or if some of the potentially responsible parties cannot be located, the authorized official may proceed against any one or more of the parties identified. The authorized official should use reasonable efforts to proceed against most known potentially responsible parties or at least against all those potentially responsible parties responsible for significant portions of the potential injury.

(iii)

(A) The authorized official shall send a Notice of Intent to Perform an Assessment to all identified potentially responsible parties. The Notice shall invite the participation of the potentially responsible party, or, if several parties are involved and if agreed to by the lead authorized official, a representative or representatives designated by the parties, in the development of the type and scope of the assessment and in the performance of the assessment. The Notice shall briefly describe, to the extent known, the site, vessel, or facility involved, the discharge of oil or release of hazardous substance of concern to the authorized official, and the resources potentially at risk. The Notice shall also contain a statement of authority for asserting trusteeship, or co-trusteeship, over those natural resources identified as potentially at risk.

(B) The authorized official shall allow at least 30 calendar days, with reasonable extensions granted as appropriate, for the potentially responsible party or parties notified to respond to the Notice before proceeding with the development of the Assessment Plan or any other assessment actions.

(b) Plan approval. The authorized official shall have final approval as to the appropriate methodologies to include in the Assessment Plan and any modifications to the Assessment Plan.

(c) Public involvement in the Assessment Plan.

(1) The authorized official must make the Assessment Plan available for review by any identified potentially responsible parties, other natural resource trustees, other affected Federal or State agencies or Indian tribes, and any other interested member of the public for a period of at least 30 calendar days, with reasonable extensions granted as appropriate. The authorized official may not perform any type B procedures described in the Assessment Plan until after this review period.

(2) Any comments concerning the Assessment Plan received from identified potentially responsible parties, other natural resource trustees, other affected Federal or State agencies or Indian tribes, and any other interested members of the public, together with responses to those comments, shall be included as part of the Report of Assessment, described in §11.90 of this part.

(d) Plan implementation. At the option of the authorized official and if agreed to by any potentially responsible party, or parties acting jointly, the potentially responsible party or any other party under the direction, guidance, and monitoring of the authorized official may implement all or any part of the Assessment Plan finally approved by the authorized official. Any decision by the authorized official to allow or not allow implementation by the potentially responsible party shall be documented in the Assessment Plan.

(e) Plan modification.

(1) The Assessment Plan may be modified at any stage of the assessment as new information becomes available.

(2)

(i) Any modification to the Assessment Plan that in the judgment of the authorized official is significant shall be made available for review by any identified potentially responsible party, any other affected natural resource trustees, other affected Federal or State agencies or Indian tribes, and any other interested members of the public for a period of at least 30 calendar days, with reasonable extensions granted as appropriate, before tasks called for in the modified plan are begun.

(ii) Any modification to the Assessment Plan that in the judgment of the authorized official is not significant shall be made available for review by any identified potentially responsible party, any other affected natural resource trustees, other affected Federal or State agencies or Indian tribes, and any other interested members of the public, but the implementation of such modification need not be delayed as a result of such review.

(f) Plan review.

(1) After the Injury Determination phase is completed and before the Quantification phase is begun, the authorized official shall review the decisions incorporated in the Assessment Plan.

(2) The purpose of this review is to ensure that the selection of methodologies for the Quantification and Damage Determination phases is consistent with the results of the Injury Determination phase, and that the use of such methodologies remains consistent with the requirements of reasonable cost, as that term is used in this part.

(3) Paragraphs (f)(1) and (f)(2) of this section do not apply to the use of a type A procedure.

[51 FR 27725, Aug. 1, 1986, as amended at 53 FR 5174, Feb. 22, 1988; 59 FR 14282, Mar. 25, 1994; 61 FR 20609, May 7, 1996]