Opinion ID: 3051262
Heading Depth: 4
Heading Rank: 2

Heading: NRDC’s NEPA Claim

Text: We next address the district court’s conclusion that NRDC has shown probable success on the merits of its claim that the Navy violated NEPA by failing to prepare an EIS for the SOCAL exercises. In our November 13, 2007 order we concluded that “Plaintiffs have shown a strong likelihood of success on the merits of their claims under [NEPA].” NRDC, 508 F.3d at 886. While that conclusion was based on our review of the record underlying the district court’s August 7, 2007 preliminary injunction order, the only subsequent developments are CEQ’s approval of “alternative arrangements” pursuant to 40 C.F.R. § 1506.11 and the Navy’s concession, by virtue of seeking such approval, that the SOCAL exercises will have a “significant environmental impact.” See 40 C.F.R. § 1506.11 (“Where emergency circumstances make it necessary to take an action with significant environmental impact without observing the provisions of these regulations, the Federal agency taking the action should consult with the Council about alternative arrangements.”) (emphasis added). Although we elaborate on our reasons, our original conclusion remains unchanged. NRDC v. WINTER 2135
As discussed earlier, NEPA requires a federal agency such as the Navy to prepare a detailed EIS for all “major Federal actions significantly affecting the quality of the human environment.” 42 U.S.C. § 4332(2)(C). However, if, as here, an agency’s regulations do not categorically require the preparation of an EIS, then the agency must first prepare an EA to determine whether the action will have a significant effect on the environment. Nat’l Parks & Conservation Ass’n v. Babbitt, 241 F.3d 722, 730 (9th Cir. 2001); see 40 C.F.R. § 1501.4. If the action will significantly affect the environment, an EIS must be prepared, while if the project will have only an insignificant effect, the agency issues a Finding of No Significant Impact (FONSI). Ocean Advocates v. U.S. Army Corps of Eng’rs, 402 F.3d 846, 864 (9th Cir. 2005); see 40 C.F.R. §§ 1501.3, 1501.4. [8] “An EIS must be prepared ‘if substantial questions are raised as to whether a project . . . may cause significant degradation of some human environmental factor.’ ” Blue Mountains Biodiversity Project v. Blackwood, 161 F.3d 1208, 1212 (9th Cir. 1998) (quoting Idaho Sporting Congress v. Thomas, 137 F.3d 1146, 1149 (9th Cir. 1998)). Thus, a plaintiff need not show that significant effects on the environment will in fact occur; raising “substantial questions whether a project may have a significant effect” on the environment is enough. Id.; Idaho Sporting, 137 F.3d at 1150. NEPA’s procedural requirements mandate that an agency take a “hard look” at the environmental consequences of its actions. Earth Island II, 442 F.3d at 1159. NEPA is unique in that it does not direct or require any particular substantive action on the part of an agency. Its sole purpose is to require that the agency be fully informed as to the environmental consequences of its actions, the mitigation measures available, and the alternatives to its proposed action. Once fully informed, the agency may make its own final rule or decision. 2136 NRDC v. WINTER However, an agency may not avoid preparing an EIS by making conclusory assertions that an activity will have only an insignificant impact on the environment. Ocean Advocates, 402 F.3d at 864. If an agency opts not to prepare an EIS, it must put forth a “convincing statement of reasons” to explain why a project’s impacts are insignificant. Blue Mountains, 161 F.3d at 1212 (quoting Save the Yaak Comm. v. Block, 840 F.2d 714, 717 (9th Cir. 1988)). [9] NEPA challenges are reviewed under the APA, which provides that an agency action may be set aside if it is “arbitrary, capricious, an abuse of discretion, or otherwise not in accordance with law[.]” 5 U.S.C. § 706(2)(A). The agency’s decisions are “entitled to a presumption of regularity. But that presumption is not to shield [the agency’s] action from a thorough, probing, in-depth review.” Citizens to Preserve Overton Park, Inc. v. Volpe, 401 U.S. 402, 415 (1971) (citations omitted). Thus, in reviewing an agency’s decision not to prepare an EIS, a court must “determine whether the agency has taken a ‘hard look’ at the consequences of its actions, ‘based [its decision] on a consideration of the relevant factors,’ and provided a ‘convincing statement of reasons to explain why a project’s impacts are insignificant.’ ” Native Ecosystems Council v. U.S. Forest Serv., 428 F.3d 1233, 1239 (9th Cir. 2005) (quoting Nat’l Parks & Conservation Ass’n, 241 F.3d at 730). Agencies have wide discretion in assessing scientific evidence, but they “must ‘take a hard look at the issues and respond[ ] to reasonable opposing viewpoints.’ ” Earth Island II, 442 F.3d at 1160 (internal quotation omitted, brackets in original). “ ‘When specialists express conflicting views, an agency must have discretion to rely on the reasonable opinions of its own experts, even if a court may find contrary views more persuasive. At the same time, courts must independently review the record in order to satisfy themselves that the agency has made a reasoned decision based on its evaluation of the evidence.’ ” Id. (quoting Marsh v. Or. Nat. Res. NRDC v. WINTER 2137 Council, 490 U.S. 360, 378 (1989)). “If an agency has failed to make a reasoned decision based on an evaluation of the evidence, we may properly conclude that an agency has acted arbitrarily and capriciously.” Id. b. Substantial Questions about the Environmental Impact of the Exercises The district court found that NRDC had raised substantial questions as to whether the SOCAL exercises would have a significant impact on the environment. Jan. 3, 2008 Dist. Ct. Order at 6-7. Accordingly, the court concluded that NRDC had demonstrated probable success on the merits of its claim that the Navy’s failure to prepare an EIS was arbitrary and capricious and in violation of NEPA and the APA. Id. at 7. The district court did not rely on an erroneous legal premise or abuse its discretion in so concluding. [10] Initially, we repeat our observation that the Navy, by seeking approval by CEQ of “alternative arrangements” pursuant to 40 C.F.R. § 1506.11, has effectively conceded that the SOCAL exercises will have a significant impact on the environment. See 40 C.F.R. § 1506.11. As the text of § 1506.11 indicates, the very purpose of the regulation is to provide for the possibility of alternative arrangements where emergency circumstances require the taking of an action “with significant environmental impact” without observing the requirements of NEPA. See id. The fact that the Navy sought relief under § 1506.11 is evidence that the Navy recognizes that the SOCAL exercises have a “significant environmental impact.” Moreover, the fact that “[t]he Navy is currently evaluating the environmental impact of MFA sonar training exercises through its development of the SOCAL Range Complex Environmental Impact Statement,” Jan. 15, 2008 CEQ Letter at 2, confirms that, at the very least, the Navy acknowledges that substantial questions have been raised as to whether the 2138 NRDC v. WINTER SOCAL exercises will have a significant impact on the environment. Accordingly, were we not to review the Navy’s EA, we would have little difficulty concluding that the district court did not rely on an erroneous legal premise or abuse its discretion in determining that NRDC has demonstrated probable success on the merits of its NEPA claim. Our own review of the EA leads us to the same conclusion.48 The Navy argues that the district court made a clearly erroneous assessment of the evidence of the effect of MFA sonar on marine mammals in the waters of southern California. Specifically, the Navy asserts that the court misunderstood the significance of the EA’s reference to the 548 predicted instances of Level A harassments of beaked whales. The Navy explains that it categorized predicted sonar exposures to beaked whales as Level A harassments not because beaked whales were expected to suffer such harassments but rather because such categorization would allow the Navy to analyze the potential impacts of MFA sonar on each beaked whale species in greater detail than it would otherwise. We find no abuse of discretion in the district court’s rejection of the Navy’s argument. The Navy’s explanation for its categorization of predicted sonar exposures to beaked whales as Level A harassments finds no support in the EA, and counsel for the Navy was unable to explain at oral argument on November 8, 2007, how classifying exposures as Level A harassments would allow the Navy to better analyze the impacts of MFA sonar on various species of beaked whales. Rather, the EA makes clear that the Navy categorized the expected exposures to beaked whales as Level A harassments because it concluded, in light of recent beaked whale strandings linked to the use of MFA sonar, that beaked whales may 48 The Navy does not reargue the merits of NRDC’s NEPA claim in its current appeal brief. We therefore assume that the Navy’s current position is the same as set forth in its brief filed with our court on September 14, 2007. NRDC v. WINTER 2139 be more sensitive to sonar exposures than other cetaceans. Because the lack of data precluded the Navy from establishing separate impact thresholds for beaked whales, the Navy decided that for beaked whales it would categorize exposures as Level A harassments that would constitute Level B harassments for other cetaceans. The Navy’s decision to do so is supported by ample evidence indicating that beaked whales are particularly vulnerable to MFA sonar. The documented strandings of marine mammals that have been linked to the use of MFA sonar overwhelmingly involve beaked whales.49 Indeed, according to the International Whaling Commission the evidence associating the use of MFA sonar with beaked whale strandings is “very convincing” and “appears overwhelming.” Similarly, a Navy-sponsored study found “completely convincing” the evidence that MFA sonar had caused strandings of beaked whales. Moreover, to the extent that a paucity of scientific data prevents the Navy from establishing meaningful impact thresholds for beaked whales, that is a reason to conduct further research and prepare an EIS—not a reason to ignore the data that does exist and proceed with the SOCAL exercises with49 We reject the Navy’s argument that the district court erred by relying on evidence not included in the Navy’s administrative record in reaching its conclusion that NRDC had demonstrated probable success on the merits. While generally a district court’s review under the APA is limited to the administrative record before the agency, it may consider evidence beyond the administrative record in certain situations. See, e.g., Ranchers Cattlemen Action v. USDA, 499 F.3d 1108, 1117 (9th Cir. 2007). The district court properly considered extra-record evidence here because the Navy never submitted an administrative record to the district court despite having had almost a year to do so since NRDC filed its complaint on March 22, 2007. The Navy has not offered any valid explanation for why it failed to submit an administrative record. We note that the Navy filed a fourteen-volume record in the related litigation concerning the 2006 RIMPAC exercise only two days after NRDC filed its complaint in that case. 2140 NRDC v. WINTER out adequate mitigation measures. As we explained in National Parks: An agency must generally prepare an EIS if the environmental effects of a proposed agency action are highly uncertain. Preparation of an EIS is mandated where uncertainty may be resolved by further collection of data or where the collection of such data may prevent speculation on potential . . . effects. The purpose of an EIS is to obviate the need for speculation by insuring that available data are gathered and analyzed prior to the implementation of the proposed action. Nat’l Parks & Conservation Ass’n, 241 F.3d at 732 (internal citations and quotations omitted). The Navy also contends that the district court misunderstood the significance of the nearly 170,000 predicted Level B harassments. First, the Navy argues that this number is an overestimate resulting from conservative assumptions in its model and from the fact that it does not take into account the mitigation measures the Navy would employ. However, the Navy stated in the EA that its prediction of the harm to marine mammals was “consistent with the best available science.” And while the Navy “assumed” that its prediction was an overestimate, it acknowledged that the science was “incomplete,” which apparently precluded the Navy from even approximating by how much it had overestimated the harm. Likewise, the Navy made no attempt to approximate how many Level B harassments its mitigation measures would prevent.50 Accordingly, we, like the Navy, must rely on the estimate of nearly 170,000 predicted Level B harassments. 50 The Navy has estimated that in the 2006 RIMPAC exercise, the employed mitigation measures prevented approximately 100 marine mammals from being exposed to MFA sonar. Even ignoring the fact that the mitigation measures employed in the 2006 RIMPAC exercise were more NRDC v. WINTER 2141 Second, the Navy argues that most of the predicted Level B harassments are below the threshold for causing temporary hearing loss and will induce only temporary behavioral responses which can be as minor as causing an animal to avoid the noise source. But according to the Navy’s own definition of Level B harassment, those temporary behavioral responses are nevertheless profound, as they cause “disruption of natural behavioral patterns . . . to a point where such behaviors are abandoned or significantly altered.”51 As the NMFS’ Biological Opinion makes clear, such disruption of natural behavioral patterns can be lethal for marine mammals. While the EA also states that it is “highly unlikely” that Level B harassments would cause disturbance to a point where behavioral patterns are abandoned or significantly altered, the EA provides no support for that statement and fails to explain why those harassments are nevertheless classified as Level B under the EA’s own definition. The district court did not abuse its discretion in determining that such a conclusory statement does not dispense with the requirement of preparing an EIS. See Ocean Advocates, 402 F.3d at 864 (“[An agency] cannot avoid preparing an EIS by making conclusory assertions that an activity will have only an insignificant impact on the environment.”). Next, the Navy argues that it was “entitled to rely” on the stringent than those the Navy has agreed to employ in the SOCAL exercises, that estimate would suggest that in the fourteen SOCAL exercises the mitigation measures would prevent only 1,400 exposures to marine mammals (14 exercises x 100 prevented exposures). Accordingly, the estimate of 170,000 Level B harassments would hardly be diminished by the Navy’s current mitigation measures. 51 The Navy derived this definition from the MMPA, 16 U.S.C. § 1362(18)(B)(ii), which was amended in 2003 to exclude from the definition those acts that disrupted natural behavioral patterns but not to the point where the behaviors were abandoned or significantly altered. See H.R. Rep. No. 99(I), 108th Cong. 1 Sess. 2003 (5/14/03). 2142 NRDC v. WINTER conclusion of the NMFS in its Biological Opinion, which the district court held satisfied the NMFS’ statutory obligation, see 16 U.S.C. § 1536(a)(2), that the SOCAL exercises were not likely to jeopardize the continued existence of threatened or endangered marine mammal species. But the NMFS opined only on the effects of MFA sonar on six species of marine mammal,52 which do not include several rare or uncommon species of marine mammal that are expected to be exposed to a significant number of sonar harassments.53 For example, the EA predicts 436 Level A harassments of Cuvier’s beaked whales. According to NOAA, as few as 1,121 Cuvier’s beaked whales may exist in California, Oregon and Washington combined. Likewise, the EA predicts 1,092 Level B harassments of bottlenose dolphins, of which only 5,271 may exist in the California Coastal and Offshore stocks. The Navy suggests that the test is whether the continued existence of marine mammal species is jeopardized. This is wrong. An agency action can have “significant effects” on the environment short of threatened extinction. NEPA regulations promulgated by CEQ provide that “significantly” has two components: context and intensity. 40 C.F.R. § 1508.27. Context refers to the setting in which the proposed action takes place, in this case the Southern California Operating Area. See id. § 1508.27(a). Intensity means “the severity of impact.” Id. § 1508.27(b). In considering the severity of the potential 52 Those six species are the fin whale, humpback whale, sei whale, sperm whale, and Guadalupe fur seal. 53 While in a recent memorandum—written well after the Navy prepared its EA—the NMFS concluded that the Navy’s own mitigation measures “will minimize the likelihood of beaked whales being caught in circumstances that characterize known strandings of beaked whales,” Jan. 9, 2008 Memorandum from NMFS to the Under Secretary of Commerce for Oceans and Atmosphere at 3, the NMFS did not conclude that the Navy’s measures would prevent direct physical injury (such as tissue damage) to beaked whales. Indeed, the NMFS acknowledged that “the mechanism by which MFA sonar appears to be injurious to beaked whales is poorly understood.” Id. at 4. NRDC v. WINTER 2143 environmental impact, a reviewing agency may consider up to ten factors to help inform the “significance” of a project, including the degree to which the effects on the quality of the human environment are likely to be “highly controversial” and the degree to which the possible effects on the human environment are “highly uncertain or involve unique or unknown risks.” Id. §§ 1508.27(b)(4), (b)(5). We have held that “one of these factors may be sufficient to require preparation of an EIS in appropriate circumstances.” Ocean Advocates, 402 F.3d at 865; see Ctr. for Biological Diversity v. Nat’l Highway Traffic Safety Admin., 508 F.3d 508, 553 (9th Cir. 2007); Nat’l Parks & Conservation Ass’n, 241 F.3d at 731. Notably, whether an agency action will jeopardize the continued existence of an endangered or threatened species is not among these factors. See 40 C.F.R. § 1508.27(b). However, the degree to which the action may “adversely affect” an endangered or threatened species is. See id. § 1508.27(b)(9). While the NMFS’ Biological Opinion concluded that the SOCAL exercises were not likely to jeopardize the continued existence of the six endangered species it studied, it nevertheless acknowledged that the exercises “may adversely affect” those species. Thus, while the Navy was not required to disregard the NMFS’ “no jeopardy” opinion, see Envtl Prot. Info. Ctr. v. U.S. Forest Serv., 451 F.3d 1005, 1012 (9th Cir. 2006), the Biological Opinion by its own terms makes clear that the SOCAL exercises may “significantly” affect the environment, see Greater Yellowstone Coalition v. Flowers, 359 F.3d 1257, 1275-76 (10th Cir. 2004) (regarding as not determinative for NEPA purposes the Fish and Wildlife Service’s “no jeopardy” opinion as to bald eagles). The Navy further argues that its finding of no significant impact was not arbitrary and capricious because no sonarinflicted injuries have been observed in the Southern California Operating Area in almost forty years of MFA sonar use by the Navy. But as explained above, that fact has limited 2144 NRDC v. WINTER probative value in establishing whether marine mammals will in fact be harmed by the Navy’s use of MFA sonar. Exposure to MFA sonar may physically and behaviorally harm marine mammals even if it does not cause them to strand. And absent stranding, such harm is difficult to observe. That is particularly true for the beaked whale—the marine mammal most vulnerable to MFA sonar—in which a population decline of 50% over 15 years would go undetected as a decline at all in 90% of the beaked whale stocks. Finally, the Navy claims that the correlation between the past marine mammal strandings and MFA sonar is irrelevant because the combination of environmental conditions “found at the locations of documented marine mammal stranding incidents” is not present in the Southern California Operating Area. But contrary to this claim, the EA indicates that the Navy has studied only the stranding in the Bahamas in 2000 and not any of the other stranding events. Moreover, while the Navy’s study of the Bahamas stranding identified a combination of factors that contributed to the whales’ injury—the presence of a strong surface duct, unusual water bathymetry, intensive use of multiple sonar units over an extended period of time, a constricted channel with limited egress, and the presence of beaked whales that appear to be sensitive to the frequencies produced by these sonars—the EA provided no supporting data or analysis for its conclusion that this combination of factors does not exist in the Southern California Operating Area. Thus, we find no abuse of discretion in the district court’s conclusion that the Navy has failed to provide the support for its conclusion that NEPA requires. See 40 C.F.R. § 1502.24. In addition, the Navy’s Bahamas study acknowledged that combinations of factors different from the one present in the Bahamas “may be more or less likely to cause strandings” (emphasis added). Thus, even if the combination of factors present in the Bahamas in fact does not exist in the Southern NRDC v. WINTER 2145 California Operating Area, the combination of factors that does exist may be even more likely to cause injury to marine mammals. The EA does not explore that possibility. [11] In sum, the district court did not abuse its discretion in concluding that NRDC raised substantial questions as to whether the SOCAL exercises would have a significant impact on the environment. All of the reasons stated in the EA for why the Navy believed the SOCAL exercises would not have the deleterious effect that the Navy’s own model predicted were cursory, unsupported by cited evidence, or unconvincing. Thus, we find ample support for the district court’s conclusion that the Navy has not “articulate[d] a rational connection between the facts found and the conclusion[ ] reached.” Earth Island II, 442 F.3d at 1156-57 (quoting Midwater Trawlers Co-op v. Envtl. Def. Ctr., 282 F.3d 710, 716 (9th Cir. 2002)). c. The Navy’s Mitigation Measures The district court also concluded that NRDC had demonstrated probable success on the merits of its claim that the Navy’s mitigation measures were inadequate to obviate the need for preparing an EIS. Again, we find no reliance on an erroneous legal premise and no abuse of discretion in the district court’s conclusion. [12] The Navy correctly points out that “[a]n agency’s decision to forego issuing an EIS may be justified in some circumstances by the adoption of [mitigation] measures” and that those measures, if significant, “need not completely compensate for adverse environmental impacts.” Nat’l Parks & Conservation Ass’n, 241 F.3d at 733-34 (citations and internal quotation marks omitted). However, we have also held that a “perfunctory description” or “mere listing of mitigation measures, without supporting analytical data,” is insufficient to support a finding of no significant impact. Okanogan Highlands Alliance v. Williams, 236 F.3d 468, 473 (9th Cir. 2000) 2146 NRDC v. WINTER (citations and internal quotation marks omitted). We find no reversible error in the district court’s conclusion that the Navy’s list of proposed mitigation measures was precisely such a perfunctory description devoid of supporting data. [13] The explanation contained in the EA as to why the mitigation measures are effective is contained in four short bullet points, stating that whales and dolphins spend extended periods of time on the surface, have relatively short dive periods, tend to move in large groups (pods), and frequently come to the surface and have a high level of activity there. Three of those bullet points in effect state the same thing, namely that whales and dolphins spend little time under water. This explanation is inadequate for several reasons. [14] First, the Navy’s explanation overlooks the fact that beaked whales spend much of their time under water, surface infrequently, and are generally difficult to detect. A study by NMFS scientists observed that “beaked whales are always difficult to see when they are on the surface, spend most of their time below the surface, and are found at low densities over large areas.” Likewise, NRDC submitted a declaration by a biologist who opines that visual monitoring by ship-based lookouts would result in the detection of only 2% of beaked whales in the Southern California Operating Area, in part because of the speed at which Navy vessels travel. Declaration of Dr. Robin William Baird ¶ 6. [15] Second, the Navy’s explanation fails to address the effectiveness of the Navy’s safety zones—the only measure that directly reduces exposure of marine mammals to MFA sonar. Specifically, the EA fails to explain why a safety zone of only 1,000 yards is adequate, why reducing the sonar level by 6dB and 10dB at the 1,000-yard and 500-yard marks, respectively, is adequate, and why it is effective to halt MFA sonar transmission altogether only at the 200-yard mark.54 The 54 As stated earlier, the Navy has recently agreed to adopt safety zones with radii of 1,000, 500 and 200 meters instead of 1,000, 500 and 200 NRDC v. WINTER 2147 Navy’s explanation also does not relate to the effectiveness of the measure requiring passive sonar to be used to detect sounds made by marine mammals. While the Navy claims in the EA that it is “very likely” that lookouts would detect a group of common dolphins because of “frequent surfacing” and group sizes of “over a thousand animals,” it notably makes no such claims about Cuvier’s beaked whales, Mesoplodont beaked whales or Ziphiid beaked whales. Indeed, the EA acknowledged that Cuvier’s beaked whales and Mesoplodont beaked whales exhibit a range of dives lasting up to 87 minutes. Moreover, while the EA claims that it is “very likely” that Baird’s beaked whales will be detected by lookouts, it states nothing about the frequency with which those whales surface. While it may be that, as the EA states, beaked whales are large in size and travel in groups of between nine and thirteen animals, those facts hardly prove the effectiveness of visual surveillance measures considering that beaked whales generally come to the surface infrequently. We find further support for the district court’s conclusion that the Navy’s mitigation measures did not obviate the need to prepare an EIS in the fact that, as explained above, the Navy refused to adopt several of the more aggressive mitigation measures recommended by the CCC, employed in the 2006 RIMPAC exercise, or imposed by the Department of yards. However, the radius of the Navy’s outer safety zone is still half of the radius recommended by the CCC, resulting in a safety zone that is 75% smaller than the one found necessary by the CCC. Notably, NRDC has submitted declarations by scientists who state that sonar levels even below the Navy’s lowest impact threshold of 173 dB may be fatal and that sonar sound can travel up to hundreds of miles under water, which suggests that the Navy’s significantly smaller safety zones are inadequate. See Parsons decl. ¶ 13, Weilgart decl. ¶ 10. 2148 NRDC v. WINTER Defense for non-RIMPAC exercises in 2006. Specifically, the Navy refused to: • Expand the outer safety zone to 2 kilometers;55 • Reduce sonar power in conditions of low visibil- ity or strong surface ducting; • Avoid training in areas known to have high con- centrations of marine mammals or during the gray whale’s migratory season; • Monitor for 30 minutes prior to commencement of MFA sonar use; • Restrict operation of MFA sonar within 25 kilo- meters from the 200-meter isobath; • Restrict operation of MFA sonar within 12 nauti- cal miles from the coast;56 and • Restrict operation of MFA sonar in choke points, constricted channels, or canyon-like areas.57 55 The Navy did not discuss this measure in its EA, let alone explain why it would not be effective. In its “after action report” following the 2006 RIMPAC exercise, the Navy disposed of this mitigation measure simply by declaring it “not prudent” and “without scientific merit.” 56 The Navy asserts on appeal that the SOCAL exercises will occur more than twelve nautical miles from the mainland coastline, but concedes that the exercises will occur within twelve nautical miles of Clemente Island, which falls within the Southern California Operating Area. In its January 3, 2008 preliminary injunction order the district court required the Navy to refrain from using MFA sonar within 12 nautical miles from the California coastline. Jan. 3, 2008 Dist. Ct. Order at 14. 57 The parties disagree as to whether there are any choke points in the Southern California Operating Area. In its January 3, 2008 preliminary injunction order the district court found that the Catalina Basin poses the same concerns as a choke point: ingress and egress to the basin are restricted and the area has a high density of marine mammals. Jan. 3, 2008 Dist. Ct. Order at 17. Accordingly, the district court ordered the Navy to refrain from using MFA sonar in the Catalina Basin. Id. at 17-18. NRDC v. WINTER 2149 Notably, as to most of these measures the Navy does not contest that they would be effective. While the Navy claims that some of the measures would adversely affect its ability to achieve the objectives of the exercises, that does not render the measures the Navy has adopted adequate to avoid the need for preparing an EIS. Indeed, the Navy states in its “after action report” following the first three SOCAL exercises that in future exercises it intends to incorporate data collection necessary to address the question of how many marine mammals not observed by lookouts may have been exposed to dangerous sonar levels, and will integrate additional monitoring tools and techniques. While the Navy’s intent is commendable, it implicitly acknowledges that its current mitigation and data collection efforts are less than adequate. [16] We conclude that the district court did not abuse its discretion in determining that the Navy’s cursory explanation in the EA for why its mitigation measures are effective does not demonstrate that those measures “constitute an adequate buffer against the negative impacts” that may result from the SOCAL exercises. See Nat’l Parks & Conservation Ass’n, 241 F.3d at 734. Accordingly, we uphold the district court’s conclusion that the Navy’s reliance on its incomplete mitigation plan in deciding not to prepare an EIS was likely arbitrary and capricious and affirm its determination that NRDC has demonstrated probable success on the merits of its NEPA claims. Cf. Wetlands Action Network v. U.S. Army Corps of Eng’rs, 222 F.3d 1105, 1112 (9th Cir. 2000).58 58 The district court also concluded that NRDC had demonstrated probable success on the merits of its claims that the Navy violated NEPA by preparing an EA that failed to adequately consider reasonable alternatives to its proposed action, see, e.g., Bob Marshall Alliance v. Hodel, 852 F.2d 1223, 1228 (9th Cir. 1998) (explaining that under NEPA federal agencies must sufficiently study, develop, and describe alternatives as part of the “environmental decisionmaking process”), as well as the cumulative impacts of its actions, see, e.g., Klamath-Siskiyou Wildlands Ctr. v. Bureau of Land Mgmt., 387 F.3d 989, 994 (9th Cir. 2004) (explaining that an EA must provide a “useful analysis of the cumulative impacts of past, 2150 NRDC v. WINTER