Sotomayor, J., concurring
If Jane spills the insecticide into the river, the effects will surely reach the riverbanks—public areas within the park’s legal boundaries. An antipollution rule tailored to apply to the Nation River as it runs through the park thus could well be “necessary or proper” to manage the parklands on either side of the river, even though the river itself is not legally a part of the park. §100751(a). And if the pollution is likely to harm nonnavigable stretches of the river downstream—public waters that are “within” the park for legal purposes—the ban also could be authorized because it specifically concerns “activities… relating to water located within [Park] System units.” §100751(b). Similar reasoning could justify a range of Service regulations, giving the Service substantial authority over navigable rivers inside geographic park boundaries in order to protect the parklands through which they flow.
Assuming that the Service has such authority over out-of-park areas pursuant to its Organic Act, nothing in ANILCA §103(c) takes it away. That section’s first sentence explains that nonpublic lands are not part of Alaska’s park units. See 16 U. S. C. §3103(c); supra, at 4–5. The second sentence then emphasizes that the Service cannot regulate nonpublic lands as if they were part of the park. Together, these sentences mean that the Service loses its authority to apply normal park rules to nonpublic lands, and instead can apply only those rules that it can justify by reference to the needs of other, public lands. For instance, the Service is unlikely to have power to apply rules against abandoning property, 36 CFR §2.22(a), or trespassing, §2.31(a)(1), to nonpublic lands amid parklands because doing so would have little or no impact on neighboring public areas within the legal boundaries of the park. But a Service regulation tailored to apply to nonparklands in order to protect sensitive surrounding parklands—like a rule against putting a toxic substance in the Nation River to stop harms to the riverbanks—would
