WSP01241

• File Number: 8220.106
• Description: Animas-La Plata
• State: CO
• Basin: San Juan/Dolores
• Water Division: 7
• Date: 1/1/2000
• Title: Correspondence regarding the Preliminary Final Supplemental Environmental Impact Statement
• Water Supply Pro - Doc Type: EIS

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06/27/00 Tlm 10:31 FAX [phone]

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mitigation has been proposed by BOR and accepted by US Fish and Wildlife Service and the
Colorado Department of Wildlife to offset these impacts. In order to. ensure that this mitigation
is successful, we recommend that a monitoring plan be developed and implemented.

Based on our Guidelines analysis, including the ecological significance of the impacts,
EP A believes that overall., either Refined Alternative 4 or Refined Alternative 6 could be
considered the least environmentally damaging alternative, Therefore, EP A accepts as
reasonable the conclusion reached by BOR that Refined Alternative 4 is the least damaging
alternative.

Turning to the remainder of the Guidelines requirements, the BOR made a reasonable
showing that Refined Alternative 4 complies with the requirements of230.1 O(b) regarding water
quality impacts and compliance with ESA. Violations of applicable water quality standards' are
not expected. By committing to monitor the potential for bioaccumulation of mercUI)' and
selenium in the proposed Ridges Basin Reservoir, any future potential impacts could be
addressed. The U.S. Fish and Wildlife Servi~ (FWS) has concurred that Refined Alternative 4
would satisfy ESA requirements based on limiting ~ua1 depletions from the San Juan River to
57,100 aCre-feet per year.

Based on the impacts discussed above relative to alternatives, we concur that the proposal
should not result in significant degradation (40 CFR 230.1 O(c)).

With respect to compensatory mitigation requirements under 40 CFR 230.1 O(d) and the
project's proposed mitigation, BOR indicates that it will continue to monitor native fish in the
Animas River beginning in 2000 and will develop a fum recommendation for mitigation no later
than 2005, at least two years prior to project pumping on the ;\n;m~. River. We recommend
that BOR' s compensatory mitigation for impacts to native fish anticipated under Refined
Alternative 4 be implemented concurrently with project construction rather than base the entire
mitigation on the results of future Project monitoring.

It is projected by the BOR that there may be an adverse effect to approximately 15% of
the habitat of the native fishery, Losses that exceed the current projection would be identified in
the proposed monitoring and would require additional steps by the BOR to address these impacts,
BOR indicates that it is not possible to replace any habitat losses for native fish in the Animas
River, but observes that off-site compensatory mitigation could be pursued, specifically in the La
Plata River near the Colorado - New Mexico border. This would involve piping water from
Ridges Basin to the La Plata River. EP A believes that it would be appropriate for BOR to
implement mitigation for this projected loss by constructing this proposed pipeline to enhance
the flows in the La Plata River. Further, BOR ~puld establish an annual review of the impact to
the native fishery in the Animas River after project operations begin. BOR should develop an
'adaptative management strategy to prevent any need for the native fish from becoming listed as
threatened or endangered under the ESA.

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