[Code of Federal Regulations]
[Title 43, Volume 1]
[Revised as of October 1, 2003]
From the U.S. Government Printing Office via GPO Access
[CITE: 43CFR11.25]

[Page 250-251]
 
                    TITLE 43--PUBLIC LANDS: INTERIOR
 
PART 11--NATURAL RESOURCE DAMAGE ASSESSMENTS--Table of Contents
 
                     Subpart B--Preassessment Phase
 
Sec. 11.25  Preassessment screen--preliminary identification of resources potentially at risk.

    (a) Preliminary identification of pathways. (1) The authorized 
official shall make a preliminary identification of potential exposure 
pathways to facilitate identification of resources at risk.
    (2) Factors to be considered in this determination should include, 
as appropriate, the circumstances of the discharge or release, the 
characteristics of the terrain or body of water involved, weather 
conditions, and the known physical, chemical, and toxicological 
properties of the oil or hazardous substance.
    (3) Pathways to be considered shall include, as appropriate, direct 
contact, surface water, ground water, air, food chains, and particulate 
movement.
    (b) Exposed areas. An estimate of areas where exposure or effects 
may have occurred or are likely to occur shall be made. This estimate 
shall identify:
    (1) Areas where it has been or can be observed that the oil or 
hazardous substance has spread;
    (2) Areas to which the oil or hazardous substance has likely spread 
through pathways; and
    (3) Areas of indirect effect, where no oil or hazardous substance 
has spread, but where biological populations may have been affected as a 
result of animals moving into or through the site.
    (c) Exposed water estimates. The area of ground water or surface 
water that may be or has been exposed may be estimated by using the 
methods described in appendix I of this part.
    (d) Estimates of concentrations. An estimate of the concentrations 
of oil or a hazardous substance in those areas of potential exposure 
shall be developed.
    (e) Potentially affected resources. (1) Based upon the estimate of 
the areas of potential exposure, and the estimate of concentrations in 
those areas, the authorized official shall identify natural resources 
for which he may assert trusteeship that are potentially affected by the 
discharge or release. This preliminary identification should be used to 
direct further investigations, but it is not intended to preclude 
consideration of other resources later found to be affected.

[[Page 251]]

    (2) A preliminary estimate, based on information readily available 
from resource managers, of the services of the resources identified as 
potentially affected shall be made. This estimate will be used in 
determining which resources to consider if further assessment efforts 
are justified.