Full opinion text
OPINION OF THE COURT SCIRICA, Circuit Judge. At issue is whether the U.S. Army Corps of Engineers can deepen the main channel of the Delaware River by five feet, enabling river ports to be economically competitive and at the same time, comply with statutes that protect the environment. The roots of the project trace back decades. In 1992, Congress authorized the project and appropriated $195 million. It continued to support the effort with regular appropriations for the next twenty years. Commencement was delayed for several reasons, but in the fall of 2009, the Corps was ready to proceed. In October 2009, New Jersey and Delaware filed suits in the District Courts of New Jersey and Delaware to enjoin the Corps from dredging the deeper channel. They alleged violations of the National Environmental Policy Act (“NEPA”), the Clean Water Act (“CWA”), and the Coastal Zone Management Act (“CZMA”). Each District Court granted summary judgment to the Corps, holding no environmental statutes would be breached. We will affirm. I. A. The federal government has maintained navigation in the Delaware River for over one hundred years. The initial project, “Philadelphia to the Sea,” was authorized by Congress in 1910 and ensures a navigation channel of 40-foot depth between Allegheny Avenue, Philadelphia, and a deep water point in the Delaware Bay, near Ship John Light. It requires the Corps to dredge 3.45 million cubic yards of material annually and to deposit the sediment at nearby locations, either owned or leased by the federal government. In 2009, the Corps used seven confined sites and one open-water site for disposal. The deepening project dates to 1954, when the Senate Committee on Public Works, by resolution, requested the Corps to study “the Delaware River between Philadelphia and the sea, for the purpose of identifying the need for any modification to the existing channel dimensions and anchorage areas.” In 1970, the House Committee on Public Works also instructed the Corps to analyze commerce along the Delaware River and to identify projects that would promote development of its ports. Pursuant to these directives, the Corps made extensive studies during the 1970s and 1980s. In 1992, it published a Feasibility Report and Environmental Impact Statement (“EIS”), recommending a deepening of five feet along the “main stem” of the Delaware River, the 102-mile stretch between the mouth of the Delaware Bay and the Philadelphia and Camden harbors. The Environmental Impact Statement predicted the deepening project would yield substantial economic benefits in the form of reduced costs to shippers. The main stem of the river hosts a concentration of heavy industry, as well as the second largest complex of oil refineries and petrochemical plants in the nation. But, as the EIS observed, “current authorized channel dimensions ... present a constraint to efficient vessel movement.” The report determined that deepening the main navigation channel by five feet would benefit oil tankers, dry bulk shippers, and other large vessels, because it would enable them to service Delaware River ports without needing to “lighter” (transfer a portion of their cargo in the lower Delaware Bay) or “light load” (travel at under-capacity). While the EIS identified potential adverse impacts to water quality, benthic organisms, and fishery resources, it concluded these would be minimal and were outweighed by the project’s benefits. Altogether, it forecast that construction and maintenance of a 5-foot deeper channel for five years would require the Corps to dredge 375 million cubic yards of material above the dredging associated with the Philadelphia to the Sea project. In June 1992, the Corps submitted the Environmental Impact Statement to Congress. That October, Congress passed the Water Resources Development Act, authorizing the deepening project to go forward. See Water Resources Development Act of 1992, Pub. L. No. 102-580, § 101(6), 106 Stat. 4797 (“WRDA”). Congress estimated the project would cost a total of approximately $295 million, with $195 million to be borne by the federal government. Id. In December 1992, the Corps issued a Record of Decision stating the deepening project was “economically justified, in accordance with environmental statutes, and in the public interest.” Not only would “transportation cost savings ... outweigh any adverse effects,” but the project was preferable to all other alternative plans, including a “no action” alternative. - After issuing the Record of Decision, the Corps initiated the Preconstruction, Engineering and Design (“PED”) phase of the project. It consulted federal and state agencies and outside experts, and conducted new environmental analyses. In 1997, the Corps published a Supplemental Environmental Impact Statement (“SEIS”). Its goals were first, to “provide additional information and environmental analysis to address environmental concerns raised during review of the 1992 [EIS]”; and second, to evaluate modifications to the deepening project that had been made since the EIS was published. Like the EIS, the SEIS recommended the project proceed. At the same time, it reduced its estimate of the amount of material to be dredged over 50 years — for initial project construction and future maintenance— from 375 to 321 million cubic yards. Like the EIS, the SEIS concluded the project would yield considerable economic benefits at a minimal environmental cost. On December 18,1998, the Corps issued a second Record of Decision stating it had “reviewed and evaluated documents concerning the proposed action, including additional PED phase studies,” and it concluded “[t]he public interest will best be served by implementing the improvements identified and described in the Feasibility Report and the Supplemental Environmental Impact Statement.” The Record of Decision reiterated that “[a]ll practical means to avoid or minimize adverse environmental effects have been incorporated into the recommended plan.” For the next eleven years, progress on the deepening project stalled. One reason for the delay was that in the mid-2000s, the Delaware River Port Authority (“DRPA”) withdrew the support it had tendered in 1999, leaving the Corps without a local partner. In June 2008, the Philadelphia River Port Authority (“PRPA”) came forward and signed a partnership agreement with the Corps. The agencies agreed to share costs: 75% for the Corps, 25% for PRPA. By late 2008, the Corps was ready to commence dredging the deeper channel. But over a decade had passed since the SEIS was published, and there were new developments. First, improved survey technology meant the deepening could be deployed more efficiently, reducing the amount of sediment. The total estimated dredging for the project over a 50-year period was reduced again, from 321 to 232 million cubic yards. Accordingly, the updated disposal plan called for using only existing, federally-owned sites — the four new disposal sites included in the SEIS were no longer necessary. Second, the construction plan now called for dredged sand from the Delaware Bay to be deposited directly onto Broadkill Beach, DE, rather than temporarily stockpiled offshore. Third, the reduction in the amount of predicted dredged material meant a wetlands restoration project at Egg Point Island, NJ, would be deferred. Finally, there were two environmental changes since 1997. An oil spill from the T/S Athos I in November 2004 had released 265,000 gallons of oil into the Delaware River, temporarily increasing the toxicity of the river’s sediments. Also, recent surveys predicted an expansion in the number and distribution of shortnose sturgeon in the Delaware River, potentially increasing the risk that rock blasting in the Marcus Hook region could cause the species. The Corps released a public notice on December 17, 2008, announcing it was undertaking a new “environmental review.” The notice stated: Notice is hereby given that the Philadelphia District, U.S. Army Corps of Engineers, is conducting an environmental review of all applicable, existing and new information generated subsequent to the Supplemental Environmental Impact Statement (SEIS) of 1997 prepared for the Delaware River Main Stem and Channel Project.... At present, the Philadelphia District has found no factors precluding the Project from moving forward based on previous studies. A summary of project changes and environmental changes known to date is attached. The public and all agencies are invited to comment on the attached changes, and to identify any applicable existing and new information generated subsequent to the 1997 SEIS by responding to this Public Notice. A copy of the SEIS of 1997 and other environmental studies performed since the completion of the SEIS, are among the information available on the District’s website. The environmental review referenced above will be used to update the environmental record, and to determine whether further environmental work and analyses are needed. On April 3, 2009, the Corps published an Environmental Assessment (“EA”). The report’s central conclusion was that no additional environmental impact statement was necessary. None of the developments since 1997 — the elimination of the four new disposal sites, the plan for direct stockpiling at Broadkill Beach, the deferment of wetlands restoration at Egg Point Island, and the possible changes to the natural environment — had materially altered the project’s environmental risk profile. Thus, the EA closed with a signed declaration by the Commander of the Corps’ Philadelphia District, stating: Based on the information contained in this EA ... 1) none of the changes to the proposed project are “substantial”; and 2) there are no new circumstances that can be considered “significant.” Therefore, I have determined that the threshold for preparation of a Supplemental Environmental Impact Statement (SEIS) ... has not been met and that changes to the project or project conditions since the 1997 SEIS will not have a significant adverse effect on the human environment. Like the Environmental Impact Statement and Supplemental Environmental Impact Statement, the Environmental Assessment recommended the project proceed because its substantial economic benefits outweighed any possible adverse environmental effects. On April 8, 2009, the Corps transmitted the 1997 Supplemental Environmental Impact Statement and 2009 Environmental Assessment to the chairs of the Senate and House Subcommittees on Energy and Water Development in the Committees on Appropriations. When Congress first authorized the deepening project in 1992, the Corps initiated a comprehensive process of discussion, coordination, and collaboration with New Jersey and Delaware to obtain the state authorizations mandated by various environmental statutes. Two statutes are relevant to this appeal. First, the Coastal Zone Management Act obligates the Corps to submit a “consistency determination” to any state whose “coastal zone” will be affected by one of its activities. 16 U.S.C. § 1456(c)(1)(A), (C). The consistency determination describes how the Corps will deploy the project “in a manner which is consistent to the maximum extent practicable” with the state’s program for managing coastal areas. Id. If the Corps receives a “concurrence,” it may proceed; if it does not, it can proceed over the state’s objection in limited circumstances. 15 C.F.R. §§ 930.41(a)-(d), 930.43(d). Second, the Clean Water Act requires the Corps to comply with all state laws “respecting the control and abatement of water pollution.” 33 U.S.C. § 1323(a). The Corps must obtain a state “water certification” when, on the basis of a federally-issued permit, it plans to discharge pollutants into a state’s navigable waters. 33 U.S.C. § 1341(a). To comply with the CZMA, the Corps submitted “consistency determinations” to the Delaware Department of Natural Resources and Environmental Control (“DNREC”) and the New Jersey Department of Environmental Protection (“NJDEP”) in 1996. Delaware identified several concerns, but provided a concurrence on May 1, 1997. New Jersey signed a Memorandum of Understanding with the Corps on August 29,1997, and on the same day, provided a concurrence. Accordingly, both CZMA clearances were in place in 1997. But each state retreated. New Jersey attempted to “revoke” its CZMA concurrence in September 2002, and requested supplemental filings from the Corps in 2008 and again in 2009. Delaware issued an order requiring the Corps to submit a new consistency determination in 2009, contending “substantial project modifications” had rendered its 1997 concurrence outdated. The Corps did not provide supplemental consistency determinations to New Jersey or Delaware. Rather, on November 9, 2009, it issued a Memorandum of Record concluding that no additional coordination was necessary for the Corps to comply with the CZMA. The Corps referred to the April 2009 EA, which had found that no substantial changes to the project had been made and no significant new information about the project’s consequences had surfaced since the 1997 SEIS. Because concurrences from each state had been in place at that point in time, and because the project’s risk profile had not changed, it was not necessary to provide supplemental consistency determinations. On January 19, 2001, the Corps initiated coordination with Delaware to comply with the Clean Water Act; that is, it applied to the Delaware Department of Natural Resources and Environmental Control for a water quality “certification” as well as for Subaqueous Lands and Wetlands permits. See 7 DeLCode chs. 60, 66 & 72. These efforts were unsuccessful. Significantly, Delaware took no action on the Corps’ application for the next eight years. On December 30, 2008, it filed a comment in response to the public notice issued by the Corps on December 17, stating it would review any new information on the project “in the context of a new Delaware sub-aqueous lands and wetlands permit application.” The implication was that Delaware had denied, by inaction, the prior requests for Subaqueous Lands and Wetlands permits and was now requesting a new application. On July 23, 2009, eight and a half years after the Corps filed its application, Delaware made its denial of the 2001 application official by order of the Secretary of DNREC. The record does not indicate whether the Corps applied for a water quality certification from New Jersey to comply with the Clean Water Act. But neither party disputes that to date, the Corps has not obtained such a certification from New Jersey. Despite these roadblocks, the Corps issued a Memorandum of Record on April 30, 2009, invoking its authority to “maintain navigation” under Section 404(t) of the Clean Water Act. See 33 U.S.C. § 1344(t). This authority, the Corps contends, relieved it of any further obligation to obtain Subaqueous Lands and Wetlands permits from Delaware. The Corps drew additional authority from Section 404(r) of the CWA, which provides a special waiver for projects that are congressionally authorized. Id. § 1344(r). It contends Section 404(r) obviated the need to obtain water quality certifications from Delaware or New Jersey. By late 2009, the Corps believed it had complied with all statutory mandates and could begin dredging the deeper channel. Under NEPA, it had published an Environmental Assessment in April 2009, concluding the project was in the public interest and that no additional environmental impact statements were necessary. Under the CZMA, it had submitted consistency determinations to New Jersey and Delaware in 1996, obtained concurrences within a year, and issued a Memorandum of Record announcing no additional CZMA coordination was necessary. Under the Clean Water Act, it had issued a separate Memorandum of Record in April 2009, invoking Section 404(t) of the Act to overcome the need for the special Delaware permits, and believed it could otherwise rely on the Section 404(r) exemption to circumvent the water quality certifications. In October 2009, the Corps entered into a contract with PRPA which authorized it to initiate the project at “Reach C,” a 12-mile stretch spanning from the Delaware Memorial Bridge to the C & D Canal. The contract did not authorize the Corps to deepen any other portion of the river until December 2010. B. On October 30, 2009 and November 2, 2009, the Delaware Department of Natural Resources and Environmental Control and the New Jersey Department of Environmental Protection initiated actions in the District Courts of Delaware and New Jersey to prevent the Corps from commencing dredging of the deeper channel. In the Delaware action, DNREC sued under the Clean Water Act, Clean Air Act, Coastal Zone Management Act, and the Delaware Code, requesting the court enjoin the Corps until it obtained the authorizations and concurrences from Delaware specified by those statutes. Delaware Riverkeeper Network (“Riverkeeper”) intervened as a plaintiff, and PRPA as a defendant. On January 29, 2010, the District Court granted in part and denied in part Delaware’s request. It preliminarily enjoined the project at Reaches A, B, D, and E, but allowed the Corps to commence at Reach C. The parties filed and cross-filed motions for summary judgment, and on December 7, 2010, the District Court dissolved its partial injunction and granted summary judgment to the Corps and PRPA. It held the Corps had properly invoked its authority to “maintain navigation” under Section 404(t) of the CWA, and this made all the difference. It held: “Having determined that the navigation exception ... is applicable here ... the Corps is exempt from compliance with the CWA, CZMA, and CAA, and judgment must be entered in its favor.” In the New Jersey action, NJDEP sought relief under NEPA, the CWA, the CZMA, the Clean Air Act, the Fish & Wildlife Coordination Act, the Water Resources Development Act, and the Magnuson-Stevens Fishery Conservation and Management Act. NJDEP asked the court to enjoin the Corps until it had “comprehensively sample[d] and analyze[d] the sediment within the areas to be dredged,” issued a new SEIS, obtained a water quality certificate from New Jersey, and completed its supplemental coordination under the CZMA. Riverkeeper again intervened as a plaintiff, and PRPA again intervened as a defendant. The parties filed and cross-filed motions for summary judgment and on January 13, 2011, the court granted summary judgment in favor of the Corps and PRPA. The court held the Corps had complied with NEPA when it issued the 2009 EA, complied with the CZMA when it declined to provide a supplemental consistency determination, and was relieved of its obligations under the CWA because Congress authorized the project in 1992. Riverkeeper and New Jersey appealed both judgments under NEPA, the CZMA, and the CWA, and we consolidated their cases for review. Delaware did not file an appeal. As this litigation unfolded, the Corps made headway on the project. After receiving court approval in January 2010, it commenced dredging at “Reach C” and completed that segment in September 2010. In November 2011, the Corps began deepening the 4-mile stretch known as “Lower Reach B,” which extends from Oldsman Creek to the Delaware Memorial Bridge. That segment is now also complete. See Delaware River Main Channel Deepening Project: Construction Status, U.S. Army Corps of Engineers Philadelphia District, http://www.nap.usace.army. mil/cenappl/drmcdp/drcs.htm (last updated Jan. 20, 2012); Jon Hurdle, New Federal Funding May Move Delaware River Channel-Deepening Project Forward, DFMNews (Feb. 20, 2012), http://www.delawarefirst.org/23188-delaware-river-channel-deepening. II. We review grants of summary judgment de novo. Startzell v. City of Phila., 533 F.3d 183, 192 (3d Cir.2008). Summary judgment is proper when the pleadings, the discovery, the disclosure materials on file, and any affidavits show that there is no “genuine dispute as to any material fact and the movant is entitled to judgment as a matter of law.” Fed.R.Civ.P. 56(a). Because appellants challenge the actions of a federal agency (the Corps) in its application of federal law (NEPA, the CWA, the CZMA, and corresponding regulations), our standard of review is informed by administrative law doctrines prescribing the degree of deference a reviewing court should apply to agency conduct. We elaborate further on the amount of deference due for each of the statutory challenges. III. New Jersey and Riverkeeper contend the Corps’ decision to proceed with the project in 2009 ran afoul of NEPA procedurally and substantively. As for procedures, appellants contend the publication of the EA was arbitrary and capricious because the Corps failed to comply with the regulations governing the preparation of NEPA studies. As for substance, appellants contend the EA fell short of the “hai’d look” demanded by NEPA on whether an SEIS was necessary. As explained below, we find all NEPA claims unavailing. A. Congress enacted the National Environmental Policy Act of 1969, Pub. L. No. 91-190, 83 Stat. 852 (codified at 42 U.S.C. § 4321 et seq.), to further two goals: ensure federal agencies consider the environmental consequences of projects before committing resources; and facilitate agencies’ communication with the public about their environmental analyses. Robertson v. Methow Valley Citizens Council, 490 U.S. 332, 350-52, 109 S.Ct. 1835, 104 L.Ed.2d 351 (1989). NEPA is a procedural statute. Its goal is to “prohibi[t] uninformed — rather than unwise — agency action.” N.J. Dep’t of Envtl. Prot. v. U.S. Nuclear Regulatory Comm’n, 561 F.3d 132, 134 (3d Cir.2009) (internal quotation marks and citation omitted). NEPA also created the Council of Environmental Quality (“CEQ”) within the Executive Office of the President, granting it authority to issue regulations effectuating NEPA. CEQ regulations are “mandatory” for all federal agencies, carry the force of law, and are entitled to “substantial deference.” See Marsh v. Or. Natural Res. Council, 490 U.S. 360, 372, 109 S.Ct. 1851, 104 L.Ed.2d 377 (1989); Andrus v. Sierra Club, 442 U.S. 347, 358, 99 S.Ct. 2335, 60 L.Ed.2d 943 (1979). In addition to CEQ regulations, agencies are bound by whatever regulations they promulgate under NEPA. E.g., 33 C.F.R. § 230 et seq. (U.S. Army Corps of Engineers’ regulations). NEPA requires federal agencies to prepare environmental impact statements before undertaking “major [fjederal actions significantly affecting the quality of the human environment.” 42 U.S.C. § 4832(C). To comply, an agency must first decide whether a contemplated project qualifies as a “major federal action significantly affecting the quality of the human environment.” CEQ regulations instruct the agency to consider both the “context” and “intensity” of the action to determine if its environmental effects will be “significant.” 40 C.F.R. § 1508.27(a)-(b). If the project qualifies, the agency should assess whether it is of a type that “[njormally requires an environmental impact assessment” or “[njormally does not require either an environmental impact statement or environmental assessment (categorical exclusion).” Id. § 1501.4(a)(1)-(2). If the action normally requires an impact statement, the agency should prepare one. If it normally requires neither an impact statement nor an assessment, the agency can proceed with the project. In all remaining situations, the agency should “prepare an environmental assessment” for the action. Id. § 1501.4(b). An EA is a “concise public document” that “[bjriefly provide[s] sufficient evidence and analysis for determining whether to prepare an [EIS].” Id. § 1508.9(a). If the agency concludes on the basis of the EA that no environmental impact statement is needed, it must issue a Finding of No Significant Impact (“FONSI”). Id. § 1501.4(e). Agencies must update — or “supplement” — their environmental impact statements over time to ensure they are current. Marsh, 490 U.S. at 370-74, 109 S.Ct. 1851. CEQ regulations instruct agencies to “prepare supplements to either draft or final environmental impact statements” in two situations: (1) if “[tjhe agency makes substantial changes in the proposed action that are relevant to environmental concerns,” or (2) if “[tjhere are significant new circumstances or information relevant to environmental concerns and bearing on the proposed action or its impacts.” 40 C.F.R. § 1502.9(c)(1); see also 33 C.F.R. § 230.13(b) (requiring the Corps to supplement an EIS “whenever required as discussed in 40 CFR 1502.09(c)”). The Supreme Court has elaborated that an agency must take a “hard look” in assessing whether either of the Section 1502.9(c) scenarios is present. Norton v. S. Utah Wilderness Alliance, 542 U.S. 55, 72-73, 124 S.Ct. 2373, 159 L.Ed.2d 137 (2004). Understandably, neither NEPA nor CEQ regulations prescribes particular proceedings agencies should use in carrying out this “hard look.” In re Operation of Mo. River Sys. Litig., 516 F.3d 688, 695 (8th Cir.2008). B. Judicial review of agency conduct under NEPA is deferential. The sole question on review is whether the agency’s actions were arbitrary or capricious. See 5 U.S.C. § 706(2)(A). When an agency publishes an EA and concludes an EIS is not needed, courts set those determinations aside only if there is evidence they were arbitrary or capricious. See Dep’t of Transp. v. Pub. Citizen, 541 U.S. 752, 763, 124 S.Ct. 2204, 159 L.Ed.2d 60 (2004) (“An agency’s decision not to prepare an EIS can be set aside only upon a showing that it was ‘arbitrary, capricious, an abuse of discretion, or otherwise not in accordance with law.’ ”) (citing 5 U.S.C. § 706(2)(A)); Soc’y Hill Towers Owners’ Ass’n v. Rendell, 210 F.3d 168, 180 (3d Cir.2000). Similarly, arbitrary and capricious review attaches to an agency decision not to supplement an EIS. Marsh, 490 U.S. at 375-76, 109 S.Ct. 1851 (“We conclude that review of the narrow question ... whether the Corps’ determination that the FEISS need not be supplemented should be set aside is controlled by the ‘arbitrary and capricious’ standard of § 706(2)(A).”). If some years pass between an agency’s completion of an EIS and its commencement of a project, a supplemental EIS may be indicated. But in Marsh, the Court made clear that judicial review of agency conduct in such situations is “narrow,” as is generally the case with arbitrary and capricious review. Marsh, 490 U.S. at 378, 109 S.Ct. 1851. An agency’s decision not to supplement an EIS “is a classic example of a factual dispute the resolution of which implicates substantial agency expertise.” Id. at 376, 109 S.Ct. 1851. Thus, the standard is still whether the action evidences arbitrary or capricious decision-making. See Town of Winthrop v. Fed. Aviation Admin., 535 F.3d 1, 3 (1st Cir.2008) (upholding the FAA’s decision in 2007 not to supplement an EIS from 2002); Ark. Wildlife Fed’n v. U.S. Army Corps of Eng’rs, 431 F.3d 1096, 1103-04 (8th Cir.2005) (upholding the Corps’ decision in 2004, after conducting an EA, not to supplement an EIS from 1999); Price Road Neighborhood Ass’n, Inc. v. U.S. Dep’t of Transp., 113 F.3d 1505 (9th Cir.1997) (upholding the Federal Highway Administration’s determination that a project change did not require a new EA). C. In our review of the Corps’ conduct, we conclude that its publication of the 2009 EA was neither arbitrary nor capricious. 1. The Corps complied with the procedural requirements prescribed by NEPA and its corresponding regulations because it engaged in a transparent and inclusive process, soliciting the views of federal and state agencies as well as of members of the public, and published an exhaustive, 179-page Environmental Assessment that reviewed the project’s risks, responded to concerns raised, and came to the reasonable conclusion the project should proceed. Neither CEQ nor Corps regulations detail the process an agency should follow when publishing an environmental assessment. See generally 40 C.F.R. § 1508.9 (CEQ regulations defining EAs); 33 C.F.R. § 230.10 (Corps regulations defining EAs). There are no notice requirements, pre-circulation requirements, or instructions about the public comments process. CEQ regulations only provide that agencies “shall involve ... the public, to the extent practicable, in preparing [environmental] assessments^]” 40 C.F.R. § 1501.4(b). This is different in the case of environmental impact statements, for which CEQ and Corps regulations are detailed. See Greater Yellowstone Coal. v. Flowers, 359 F.3d 1257, 1279 (10th Cir.2004) (“NEPA’s public involvement requirements are not as well defined when an agency prepares only an EA and not an EIS.”). The Corps’ procedures in preparing and publishing the 2009 EA satisfied Section 1501.4(b)’s directive to “involve ... the public to the extent practicable.” On December 17, 2008, the agency published a notice stating it was undertaking an “environmental review” in order “to update the environmental record, and to determine whether further environmental work and analyses are needed.” The Corps provided a summary of changes to the project that had been made since 1997 and links to the SEIS, EIS, and reports by other federal agencies. Collectively, the notice and appended materials communicated to the public that the Corps was undertaking a new environmental study of the deepening project and that its goal was to determine whether “further environmental work,” such as a new SEIS, was needed. It directly provided the public with access to the information it would rely upon and solicited comments. The 30-day comment period was equal to the length of time mandated by CEQ regulations for comment periods for final EIS studies. 40 C.F.R. § 1506.10(b)(2). The Corps was transparent, clear, and inclusive. After soliciting and reviewing the public comments, the Corps published a thorough, 179-page Environmental Assessment on April 3, 2009. The report addressed the substance of the most important issues raised in the comments — questions about sediment quality, water quality, air quality, biological resources, and the impacts of the Athos oil spill. Each environmental risk, the report concluded, was minimal and could be mitigated through appropriate implementation measures. The Corps also responded in great detail to a comment filed by the New Jersey Department of Environmental Protection on January 14, 2009, sending the agency a letter on April 24, 2009 that reiterated the findings of the EA and expounded on its conclusions. Despite the Corps’ comprehensive public engagement, appellants contend it acted arbitrarily and capriciously under NEPA. They argue the Corps provided inadequate public notice; erred in declining to publish a FONSI alongside the EA; erred in not circulating a draft of the EA for public review before publication; and did not meaningfully review the comments submitted. None of these claims has merit. Regarding public notice, appellants contend the Corps did not specify the form of its forthcoming “review,” i.e., that it would be an Environmental Assessment, and that the comment period fell during a time of year when many people are on vacation. But as explained, neither NEPA nor its corresponding regulations impose a public notice requirement for EAs. See generally 40 C.F.R. § 1508.9; 33 C.F.R. § 230.10. The CEQ regulations only direct that agencies “involve ... the public, to the extent practicable.” 40 C.F.R. § 1501.4(b). The December 17, 2008 notice satisfied this mandate by describing a forthcoming “environmental review” that would be “used to update the environmental record, and to determine whether further environmental work and analyses are needed.” Furthermore, the Corps appended a wealth of materials to its notice to make evident the information it would rely upon and to solicit feedback on that information. Courts have upheld EAs preceded by public notices with the same or with considerably less detail than that here. E.g., Theodore Roosevelt Conservation P’ship v. Salazar, 616 F.3d 497, 519 (D.C.Cir.2010) (involving a public notice that did not “supplfy] any specific environmental information”); Bering Strait Citizens for Responsible Res. Dev. v. U.S. Army Corps of Eng’rs, 524 F.3d 938, 952-53 (9th Cir.2008) (involving a notice that did not specify an EA was being prepared); Alliance To Protect Nantucket Sound, Inc. v. U.S. Dep’t of Army, 398 F.3d 105, 108, 115 (1st Cir.2005) (involving a notice that did not mention a forthcoming EA). Second, appellants fault the Corps for publishing the EA without issuing a Finding of No Significant Impact. But neither CEQ nor Corps regulations impose a FONSI requirement in this context — an agency deciding, on the basis of an EA, whether to issue a supplemental EIS. The regulations require FONSIs only when the agency employs an EA to decide whether to issue an initial EIS. See 40 C.F.R. § 1501.4(e) (instructing agencies to prepare “a finding of no significant impact (§ 1508.13) if the agency determines on the basis of an environmental assessment not to prepare a[n environmental impact] statement”); 33 C.F.R. § 230.11 (“A FON-SI shall be prepared for a proposed action, not categorically excluded, for which an EIS will not be prepared.”). Given that CEQ and Corps regulations authorize the use of EAs for a wide array of purposes, see 40 C.F.R. § 1501.3(b) (“Agencies may prepare an environmental assessment on any action at any time in order to assist agency planning and decisionmaking.”); 33 C.F.R. § 230.10(c), their silence on FON-SIs for all but the initial EIS-determination is instructive. The Corps was not required to issue a FONSI, and its decision to refrain from doing so was not arbitrary or capricious. See In re Operation of Mo. River Sys. Litig., 516 F.3d at 695 (“[T]he Corps prepared an EA, not to help it decide whether to prepare an EIS, but rather to determine whether the change in agency action required an SEIS. As this case illustrates, it is reasonable to expect that the Corps will sometimes determine that a FONSI is not appropriate because the action being taken has a significant impact on the environment, but an SEIS is not required because the impact was sufficiently analyzed in an earlier FEIS [Final Environmental Impact Statement]. This approach is neither a misuse of the EA procedure nor a violation of NEPA.”). Third, appellants contend the Corps’ failure to circulate a draft of the EA before final publication was procedurally invalid. But neither CEQ nor Corps regulations impose a universal requirement to circulate draft EAs before publication. The CEQ regulations instruct that a document be disseminated for public review only when it is a draft or final EIS, 40 C.F.R. § 1506.10(b), or involves a “proposed action” that (i) would normally require an EIS which the agency has decided to forgo, or (ii) is “without precedent,” id. § 1501.4(e)(2)(i), (ii). The Corps’ regulations require that EAs be circulated before publication only when they concern “feasibility, continuing authority, or special planning reports and certain planning/engineering reports.” 33 C.F.R. § 230.11. The EA for the deepening project did not fall into any of these categories. See Bering Strait Citizens, 524 F.3d at 952 (“We hold today that the circulation of a draft EA is not required in every case.... Our conclusion is consistent with the views of other circuits, which uniformly have not insisted on the circulation of a draft EA.”); Fund for Animals, Inc. v. Rice, 85 F.3d 535, 549 (11th Cir.1996) (holding there was “no legal requirement that an Environmental Assessment be circulated publicly and, in fact, they rarely are” (emphasis omitted)). Meanwhile, although some evidence in the record suggests the Corps often released EAs for public review before publication, this was a nonbinding internal practice from which the Corps had discretion to deviate. United States v. Caceres, 440 U.S. 741, 754 n. 18, 99 S.Ct. 1465, 59 L.Ed.2d 733 (1979) (“[A]geneies are not required, at the risk of invalidation of their action, to follow all of their rules, even those properly classified as ‘internal.’ ”). It exercised that discretion reasonably, given the long history of public involvement in reviewing and commenting on the deepening project, including the recent four-week comment period, and given the EA’s central conclusion that no factor or development altered the findings of the earlier reports. E.g., Pogliani v. U.S. Army Corps of Eng’rs, 306 F.3d 1235, 1240 (2d Cir.2002) (refusing to grant a preliminary injunction based on the Corps’ decision not to circulate a draft EA because the action was not one which “normally requires” an EIS nor “without precedent” under 40 C.F.R. § 1501.4(e)(2), and so did not have a pre-circulation requirement). Finally, appellants contend the Corps failed to meaningfully consider the public comments it received on its December 17, 2008 notice. But the 179-page Environmental Assessment comprehensively addressed the key issues raised in the comments. See supra. Furthermore, the record demonstrates over twenty years of engagement by the Corps with the public, state governments, and other federal agencies. The Corps’ activity in the 2008-2009 period was the final chapter of this engagement. On May 4, 1989, the Corps issued a notice of intent to file a Draft Environmental Impact Statement on the deepening project. It circulated a copy of that report for public comment on July 13, 1990, and released a final EIS in February 1992, incorporating the comments received. The Corps repeated this public engagement process for the SEIS in 1997. Between 1992 and 2008, it had a steady stream of communications with the EPA, New Jersey, and Delaware about the project’s compliance with the Clean Water Act and the Coastal Zone Management Act. It also engaged in rigorous coordination with the National Marine Fisheries Service (“NMFS”), conducting an Endangered Species Act consultation in 1996 and preparing a Biological Assessment for the agency in 2009. Given this twenty-plus year period of public, inter-state, and inter-agency involvement, the assertion that the Corps failed to engage the public or respond to its views lacks merit. 2. NEPA not only requires that agencies follow certain procedures when assembling environmental reports, but also that they take a “hard look” at the environmental costs of the proposed action as compared to the contemplated benefits. See Baltimore Gas & Elec. Co. v. Natural Res. Def. Council, Inc., 462 U.S. 87, 98, 103 S.Ct. 2246, 76 L.Ed.2d 437 (1983) (“Congress, in enacting NEPA----required [] that the agency take a ‘hard look’ at the environmental consequences before taking a major action.”); Vt. Yankee Nuclear Power Corp. v. Natural Res. Def. Council, Inc., 435 U.S. 519, 524, 98 S.Ct. 1197, 55 L.Ed.2d 460 (1978). The Corps provided the necessary “hard look” at the project’s costs and benefits, and at whether an additional SEIS was needed for the project, in the 2009 EA. Riverkeeper and New Jersey advance three reasons for why the agency’s review was not sufficient, none of which is convincing. First, Riverkeeper argues the EA failed to adequately address the adverse impacts the project could cause on the shortnose sturgeon. The shortnose sturgeon was included in the federal Endangered Species list at least as far back as 1996, meaning it bore that classification at the time the SEIS and EA were published. Some agencies and organizations had expressed concern during the comments period that the analysis of the shortnose sturgeon in the 1997 SEIS was no longer sufficient. New information about the species and its use of the Delaware River had become available, such that “the proposed deepening may affect shortnose sturgeon in a manner or to an extent not considered” previously. The EA contained no fewer than four separate sections on the shortnose sturgeon, including a comprehensive assessment of the species in an appended Essential Fish Habitat Evaluation. The report acknowledged that recent surveys showed “a significant expansion in the number and distribution of shortnose sturgeon in the Delaware River appears likely,” but it also cited a 2005 study which found that “large aggregations of sturgeon do not exist in the blasting area.” Furthermore, it explained how blasting techniques could be honed to minimize harm to the species. The Corps drew on these analyses — as well as its findings in a Biological Assessment published for NMFS earlier that year — to conclude that adverse impacts to the shortnose sturgeon would be minimal. The Corps’ conclusion was neither arbitrary nor capricious. Riverkeeper also contends the EA did not give a hard look to the dangers confronting the Atlantic sturgeon. NMFS designated the Atlantic sturgeon as a “candidate” for the Endangered Species list in 2006, and throughout the time at issue in this litigation, it retained that classification. “Candidate” species receive no statutory protection under the Endangered Species Act, but their vulnerability makes them appropriate for consideration in a NEPA review. The EA’s analysis of the Atlantic sturgeon was sufficient. The report contained two sections on “threatened and endangered species and other species of special concern,” each of which contained a subsection on the Atlantic sturgeon. The sturgeon’s use of the Delaware River— from spawning, to hatching, to other migratory patterns — was analyzed in detail. Furthermore,- every public comment about the vulnerability of the species that River-keeper cites in its Brief was also addressed in the EA. See Riverkeeper Br. at 85 (citing comments by NMFS, Prof. Dewayne Fox, and the Delaware River Basin Fish and Wildlife Management Cooperative). The Delaware River Basin Fish and Wildlife Management Cooperative filed a comment recommending the Corps “establish dredging and blasting windows that would result in the lowest probable impact to existing sturgeon populations of both Atlantic as well as shortnose.” The EA adopted this proposal: “All of these windows will be met during construction of the deepening project,” save for one, which was infeasible. Professor Dewayne Fox of Delaware State University advised the Corps to take into account “the large body of work ... done primarily by both DSU and the Delaware Department of Fisheries and Wildlife” about the Atlantic sturgeon. The EA devoted three pages to the studies of Professor Fox. NMFS informed the Corps it would “recommend protective measures” for the Atlantic sturgeon. The Corps committed to using “environmental windows” and “[cjonstruction techniques” to “reduce the impacts of rock blasting on fish,” and to working collaboratively with NMFS during the project design phase. Finally, New Jersey contends the EA’s analysis of potential water contamination was deficient. In two ways, New Jersey argues, the EA lacked the necessary data for a robust analysis. First, it did not include up-to-date sediment samples from “bend-widening areas” in the Delaware River, which are necessary to obtain ‘“a worst case picture of contaminant concentrations that would potentially be in the dredged material.’ ” N.J. Reply Br. 19 (citing the SEIS). Second, New Jersey-claims the EA omitted a “modified elutriate analysis,” which was important for predicting how dredged material, stored upstream, would impact surface water quality. Neither purported data shortcoming rises to the level of arbitrary or capricious action. The EA relied on a broad array of studies, surveys, and sediment samples to ground its analysis of the potential water contamination from the project. First, it relied on sediment samples evaluated in the SEIS, which New Jersey concedes included samples from bend-widening areas. These had shown no bioaccumulation of any significance in the river’s sediment, and no potential for the deepening to increase the water’s toxicity. Second, the EA “incorporated ... by reference” the modified elutriate analysis from the SEIS, which similarly concluded that “dredging and dredged material disposal operations would not significantly impact water quality within the Delaware River.” Third, the EA relied on two studies by the Corps in 2003 and 2005, analyzing “[a] total of 45 sediment cores” from the main channel and concluding there was negligible contamination. Finally, the EA relied on 162 sediment samples collected by the National Oceanic and Atmospheric Administration from intertidal and subtidal areas for a 2007 report. These samples showed the 2004 oil spill had left no lingering effects and “baseline conditions (i.e., no spill-associated service losses) [wejre reached in 14 months.” Altogether, this material provided the Corps a sufficient basis from which to analyze how the project would impact water contamination in the Delaware River and from which to draw well-reasoned, non-arbitrary conclusions. IV. Riverkeeper contends the Corps’ decision to proceed with the deepening project violated the Clean Water Act. First, River-keeper argues it violated Section 401(a), which requires recipients of federal permits who release “discharge” in navigable waters to obtain “a certification from the State in which the discharge originates or will originate.” 33 U.S.C. § 1341(a)(1). The Corps never secured water certifications from New Jersey or from Delaware for the project. Second, Riverkeeper contends the Corps’ actions ran afoul of Sections 313 and 404(t), which obligate federal agencies to comply with state environmental regulations when engaging in dredging operations. 33 U.S.C. § 1323(a); id. § 1344(t). After eight years of delay, Delaware denied the Corps two permits required by state law for users of subaqueous lands and wetlands in July 2009; nonetheless, the Corps decided to proceed. In response to Riverkeeper’s challenges, the Corps contends it is entitled to two statutory exemptions codified at Sections 404(r) and 404(t) of the CWA. For the reasons stated, we hold that both exemptions attach. A. The Clean Water Act (“CWA”) was enacted in 1972 to “restore and maintain the chemical, physical, and biological integrity of the Nation’s waters.” Federal Water Pollution Control Act, Pub. L. No. 92-500, § 101(a), 86 Stat. 816 (1972). Under its principal provision, “the discharge of any pollutant by any person shall be unlawful.” 33 U.S.C. § 1311(a). The “discharge of a pollutant” is defined as “any addition of any pollutant to navigable waters from any point source,” see id. § 1362(12); “navigable waters” are defined as “waters of the United States, including the territorial seas,” id. § 1362(7); and “pollutant” is defined as including “dredged spoil, ... rock, sand, [and] cellar dirt,” id. § 1362(6). The Delaware River readily qualifies as a “navigable water” because it is a “relatively permanent ... continuously flowing bod[y] of water forming geographic features that are described in ordinary parlance as ... rivers,” Rapanos v. United States, 547 U.S. 715, 739, 126 S.Ct. 2208, 165 L.Ed.2d 159 (2006) (internal quotation marks and citation omitted); and dredging qualifies as the “discharge of a pollutant” because it results in the “addition” of “dredged spoil” to a navigable water. Under Section 404(a), however, the U.S. Army Corps of Engineers may “issue permits ... for the discharge of dredged or fill material into the navigable waters at specified disposal sites.” See CWA § 404(a) (codified at 33 U.S.C. § 1344(a)). The Corps “exercises the discretion of an enlightened despot” in issuing discharge permits, Rapanos, 547 U.S. at 721, 126 S.Ct. 2208, and considers a broad range of factors set forth in its regulations, see 33 C.F.R. § 320.4. But there is one statutory obligation incumbent upon the Corps. Before issuing a permit, it must apply “guidelines developed by the Administrator [of the EPA], in conjunction with the Secretary [of the Army],” which prescribe a rigorous review of a project’s environmental costs. CWA § 404(b)(1) (codified at 33 U.S.C. § 1344(b)); 40 C.F.R. § 230.10 et seq. The Clean Water Act requires federal agencies and holders of federally-issued discharge permits to comply with state and local environmental laws in two pertinent ways. First, under Section 401(a), the Act requires holders of U.S. Army Corps permits, issued pursuant to Section 404, to obtain “certifications” from the states in which the discharge into navigable waters will occur. CWA § 401(a) (codified at 33 U.S.C. § 1341(a)(1)) (“Any applicant for a Federal license or permit to conduct any activity ... which may result in any discharge into the navigable waters, shall provide the licensing or permitting agency a certification from the State in which the discharge originates or will originate ... that any such discharge will comply with the applicable provisions of [other sections of this title].”). The state certification “shall become a condition of any Federal license or permit subject to the provisions of this section.” 33 U.S.C. § 1341(d). Second, under Sections 313 and 404(t), the Act requires federal departments and instrumentalities to comply with state environmental laws when they engage in activities that emit pollutants into navigable waters. CWA § 313 (codified at 33 U.S.C. § 1323(a)) (“Each department, agency, or instrumentality of the executive, legislative, and judicial branches of the Federal Government ... shall be subject to, and comply with, all Federal, State, interstate, and local requirements ... respecting the control and abatement of water pollution____”); CWA § 404(t) (codified at 33 U.S.C. § 1344(t)) (“[Every federal] agency shall comply with such State or interstate requirements both substantive and procedural to control the discharge of dredged or fill material to the same extent that any person is subject to such requirements.”). But the Act also provides exceptions to the provisions cited, enacted as part of the Clean Water Act of 1977, Pub. L. No. 97-217, 91 Stat. 1566. As to the water certification requirement under Section 401(a), Section 404(r) creates an exemption for projects “specifically authorized” by Congress. See CWA § 404(r) (codified at 33 U.S.C. § 1344(r)) (“The discharge of dredged or fill material as part of the construction of a Federal project specifically authorized by Congress ... is not prohibited by or otherwise subject to regulation under this section.... ”). As to the mandates to follow states’ environmental laws, codified at Sections 313 and 404(t), the final sentence of Section 404(t) provides a partial waiver. See CWA § 404(t) (codified at 33 U.S.C. § 1344(t)) (“This section shall not be construed as affecting or impairing the authority of the Secretary to maintain navigation.”); see also S.Rep. No. 95-370, at 68-69 (1977), 1977 U.S.C.C.A.N. 4326, 4393 (“[C]orps dredging activities are not exempt from State pollution abatement requirements.... [But this] is neither intended nor expected to result in compromising the ability of the corps to maintain navigation.”). Before Section 404(t) was added in 1977, the CWA had included a provision, still in force, that similarly preserved the Corps’ authority to “maintain navigation.” See CWA § 511(a)(2) (codified at 33 U.S.C. § 1371(a)(2)) (“This chapter shall not be construed as ... affecting or impairing the authority of the Secretary of the Army (A) to maintain navigation or (B) under the Act of March 3, 1899[.]”). B. The Corps asserts it was relieved of the need to obtain water certifications from New Jersey and Delaware under Section 401(a) of the CWA by virtue of the “eongressionally authorized” exception under Section 404(r). Riverkeeper disagrees, but we find the Corps’ argument convincing. As an initial matter, we agree with the Corps that “all of the elements of section 404(r) have been satisfied” for the deepening project. Section 404(r) provides: The discharge of dredged or fill material as part of the construction of a Federal project specifically authorized by Congress ... is not prohibited by or otherwise subject to regulation under this section ... if information on the effects of such discharge, including consideration of the guidelines developed under subsection (b)(1) of this section, is included in an environmental impact statement for such project pursuant to the National Environmental Policy Act of 1969 [42 U.S.C.A. § 4321 et seq.] and such environmental impact statement has been submitted to Congress before the actual discharge of dredged or fill material in connection with the construction of such project and prior to either authorization of such project or an appropriation of funds for such construction. 33 U.S.C. § 1344(r). Accordingly, to trigger Section 404(r), there must be a federal project specifically authorized by Congress. The deepening project unquestionably qualifies, as Congress clearly authorized it in the Water Resources Development Act of 1992, Pub. L. No. 102-580, § 101(6), 106 Stat. 4797, 4802 (“[T]he following projects for water resources development and conservation and other purposes are authorized to be carried out by the Secretary.... The project for navigation, Delaware River Mainstem and Channel Deepening, Delaware, New Jersey, and Pennsylvania: Report of the Chief of Engineers, dated June 29, 1992, at a total cost of $294,931,000, with an estimated Federal cost of $195,767,000....”). Section 404(r) also requires that “information on the effects of [the project], including consideration of the guidelines developed under subsection (b)(1)” be “included in an environmental impact statement ... submitted to Congress before the actual discharge of dredged or fill material ... and prior to either authorization of such project or an appropriation of funds for such construction.” 33 U.S.C. § 1344(r). This prerequisite was met. The Corps transmitted an EIS to Congress in June 1992 that had been prepared pursuant to NEPA and that included, as Section 404(r) directs, a “consideration of the guidelines developed under subsection (b)(1).” The transmission occurred five months before Congress authorized the project or appropriated funds, see WRDA, 106 Stat. at 4797 (showing a date passage of October 31, 1992), and years before any “actual discharge” occurred. Nonetheless, Riverkeeper contends Section 404(r) does not apply for two reasons. The first is that the 1992 EIS was incomplete because it lacked a Record of Decision. The Record of Decision was issued in December 1992, two months after the WRDA was enacted. But this is of no moment. Section 404(r) mandates that “[an] environmental impact statement ... [prepared] pursuant to the National Environmental Policy Act” be provided to Congress and that it “includ[e] consideration of the guidelines developed under subsection (b)(1)”; it never mentions a Record of Decision. The absence of a Record of Decision in the congressional submission violates no statutory command. Furthermore, the purpose of Section 404(r) is for Congress to receive sufficient information in order to make an informed judgment about whether to authorize a federal project. In cases like this, where an EIS is produced after a full-fledged notice and comment process, bears the title of “final” impact study, and is transmitted to Congress with an explicit request for a Section 404(r) exemption, that purpose has been achieved. Second, Riverkeeper contends the SEIS invalidated whatever exemption had been attained by virtue of the EIS. Riverkeeper claims the SEIS stands as proof that by 1997, the deepening project had changed to such an extent and new information had become available to such a degree, that Congress’s 1992 statutory authorization was no longer binding. But nothing in the text of Section 404(r) suggests that once the exemption attached, it lapses. The plain language of the statute states that when Congress “specifically authorizes” a federal project, following its consideration of an EIS, the exemption is triggered. 33 U.S.C. § 1344(r). There is no requirement that the agency submit supplemental NEPA reports so Congress can reauthorize the venture. Furthermore, the SEIS’s central findings were that despite the developments between 1992 and 1997 — e.g., modifications to the project, new scientific information that became available — the conclusions in the EIS still applied. The SEIS stated: “[Refinements to the authorized plan that were recommended in the 1992 Interim Feasibility Report.... did not alter the environmental impacts that were presented in the Final Environmental Impact Statement” and the project still “complied] with the 404(b)(1) guidelines.” There was no need to solicit reauthorization from Congress because the project had not changed in a material way. In sum, Section 404(r) of the CWA was triggered in 1992 and did not lapse by virtue of the Corps’ subsequent NEPA analyses. The Corps was relieved of the federal permitting requirement under Section 404, see 33 C.F.R. § 323.4(d) (explaining that “[fjederal projects which qualify under the criteria in section 404(r) of the CWA are exempt from section 404 permit requirements”), as well as from the water certification requirement under Section 401(a), see 33 U.S.C. § 1341(a)(1) (stating the certification mandate attaches to “applieant[s] for a Federal license or permit to conduct any activity”). The fact that the Corps attempted to work collaboratively with New Jersey and Delaware for several years does not undermine its lawful reliance on the Section 404(r) exemption. C. The Corps contends it was relieved of Sections 313 and 404(t) of the Clean Water Act, which required it to obtain special Delaware permits, because it was entitled to a statutory exemption codified at Section 404(t). We afford Skidmore deference to the Corps’ invocation of Section 404(t) and find its interpretation of the statute reasonable. We also find the Corps was neither arbitrary nor capricious in deciding to invoke Section 404(t). The Delaware Subaqueous Lands Act “empower[s] the Secretary to deal with or dispose of interest in public subaqueous lands.” 7 DeLCode Ann. tit. 7, § 7201. Under that authority, DNREC promulgated regulations instructing that “[n]o ... project which may potentially impact the public interest in the use of tidal or navigable waters [or] contribute to water pollution ... shall be undertaken on public or private subaqueous lands unless approval has been obtained from the Department.” 7 Del. Admin. Code § 7504-2.7. The Delaware Wetlands Act provides that “[a]ny activity on the wetlands requires a permit from [DNREC].” 7 Del.Code Ann. tit. 7, § 6604(a). The word “activity” is defined to include dredging operations. Id. § 6603. Both permit requirements extend to the deepening project because it calls for the disposal of dredged material at three subaqueous land-sites in Delaware and for a wetlands restoration project in Delaware. The Corps applied for subaqueous lands and wetlands permits in 2001. For eight years, Delaware stalled on its application. In light of Sections 313 and 404(t) of the CWA, which obligate federal agencies to follow states’ environmental laws, the Corps was at an impasse. Accordingly, it invoked the exemption set forth in Section 404(t) in the spring of 2009. That provision provides: “This section shall not be construed as affecting or impairing the authority of the Secretary to maintain navigation.” CWA § 404(t) (codified at 33 U.S.C. § 1344(D). On April 30, 2009, the Assistant Secretary of the Army for Civil Works signed a Memorandum of Record declaring the “failure to construct the 45 Project as authorized by Congress in 1992 has ... impaired the Secretary of the Army’s authority to maintain navigation .... ” The Assistant Secretary was “directing] the Corps to proceed with construction of the project.” The Memorandum of Record cited Se