On December 21, 2000, OPS issued their final rule on the definition of Unusually Sensitive Areas (USAs). This final rule defines drinking water and ecological areas that are unusually sensitive to environmental damage if there is a hazardous liquid pipeline release. RSPA will map USA locations on a state by state basis, beginning with the states that have the largest number of liquid pipeline miles. RSPA expects to complete the first ten states by the end of the year. These states include Texas, Oklahoma, Kansas, Louisiana, Illinois, Wyoming, New Mexico, California, Missouri, and Montana. The remaining states are expected to be completed by the end of 2001. RSPA intends to update the USA maps every five years, contingent on the availability of funding and resources.

This final rule is available on RCP's website at 65 FR 80530 . It does not require specific action by pipeline operators but will be used in existing and future regulations, such as:

• Integrity Management Rule. Applies to hazardous liquid pipelines that are in, or could effect, a USA.
• Risk-based Alternative to Pressure Testing Older Hazardous Liquid and Carbon Dioxide Pipelines. RSPA may clarify that USAs must be considered in identifying areas of environmental sensitivity.
• Response Plans for Onshore Oil Pipelines under 49 CFR part 194. RSPA may amend the definition of environmental importance to include USAs.
• Area Contingency Plans. Area Committees and OPS may use the USA definition in reviewing and validating response plans and response plan revisions.
• Low Stress Pipelines. Currently pipelines operating at low stress in rural areas are exempt from compliance with 49 CFR 195 requirements. RSPA may consider removing this exemption for low stress lines that could impact USAs.

There were a number of comments on the proposed rule. Many proposed changes were not adopted, as described in the preamble to the rule, while other suggested changes were adopted. Some important differences between the proposed rule and the final rule include:

• Source water protection areas (SWPAs) have replaced wellhead protection areas (WHPAs), specifically the areas of primary influence. Where SWPAs have not been created, WHPAs will be continue to be used to identify USAs.
• A preliminary drinking water USA is considered to be a USA unless it is verified that an adequate alternative drinking water source exists. The adequate alternative drinking water source definition has been changed to extend the amount of time needed for the backup water source from one month to six months for groundwater systems.
• The final definition removes the doubling of SWPAs and WHPAs in sole source aquifers. RSPA has included the recharge areas of sole source aquifers that are karst in nature in the final USA definition.
• RSPA added critically imperiled and imperiled rare ecological communities, such as California’s vernal pools, as ecological USA candidates, with the caveat that the natural community data must match recent nomenclature and conservation status rank conventions. In the pilot states, adding rare communities increased the amount of land mass by less than 1% in Louisiana and California. It did not increase the land mass covered in Texas.
• RSPA made imperiled, threatened and endangered, and depleted marine mammal species that are aquatic or aquatic dependent or are terrestrial and have a limited range USAs. In the pilot states, adding aquatic, aquatic dependent, and limited range species increased the amount of land mass by less than 2% in Texas, 4% in California, and 13% in Louisiana.
• RSPA added to the USA definition imperiled, threatened or endangered, or depleted marine mammal species occurrences and imperiled ecological community occurrences that are in the best condition and are therefore the most viable. In the pilot states, adding rare communities increased the amount of land mass by less than 1% in Texas, by 2% in California, and by 4% in Louisiana.
• RSPA will consider extending protection to other environmentally sensitive and vital resources such as national parks, wetlands, wildlife preservation areas, refuges, fish hatcheries, vulnerable species, cultural resources, recreation areas, and economic resource areas through future rulemaking.
• RSPA will also analyze new, revised, or refined drinking water and ecological programs every five years to determine if other programs should be added to the USA definition.

RSPA will propose any revisions to the USA definition in a notice of proposed rulemaking. As additional ecological and drinking water resource information becomes available, and RSPA identifies and locates additional USAs, the operator has the responsibility to apply this new information in its integrity management program.