(TLDR... this area is subject to a specific kind of protection that emphasizes protection over recreation. I wanted talk a bit in general about how these things work, because it's not super obvious from the outside. I'm not an expert in any of this, but my undergrad was in environmental science, where we talked a lot about this stuff.)
> It seems like they are repurposing the park and hiding behind the wildlife assessment.
"Park" here is a bit of an ambiguous term. This area was designated a "National Lakeshore" in 1970, which is a lot more protection than your typical county park would have. In this case the federal government, by act of Congress, stepped in and said they wanted to preserve this land for the future, unimpaired. https://www.nps.gov/articles/nps-designations.htm and https://en.wikipedia.org/wiki/Sleeping_Bear_Dunes_National_L.... This protection is closer to something like Yellowstone or Yosemite than your local fishing spot. And apparently its management was always contentious: https://www.nps.gov/parkhistory/online_books/slbe/adhi_intro...
In other words, Congress specifically tasked the NPS to preserve this area, which is a specific designation that is meant to emphasize natural resource preservation over recreational usage. There are other land designations too, both higher like wilderness (MUCH more protected) and lower (like most USFS and BLM land, which can be managed for resource extraction alongside recreation, with limited conservation).
Probably the area shouldn't have ever been dredged for recreation, if they were to follow the true spirit of the law. But NPS personnel and values have changed over time too, as well as our science, and over time it probably has become more protective than in the past (like we don't feed the bears in Yosemite anymore).
Most of Lake Michigan doesn't have this sort of designation; it was only a few scenic spots that Congress wanted to protect (most recently, Indiana's dunes were added a few years ago).
> The environment impact is rather long but it appears to essentially say less human activity and boats may cause less disturbance to wildelife. Although this seems to undermine the point of it making the beach more accessible to other humans. I didnt see any acute or specific harm cited like damaging some endangered species or something.
PDF pages 28 and 29 summarizes the impacts and tries to weigh the pros and cons of various "alternatives". An "alternative" here is just an "option", i.e., a bunch of what-if scenarios. Alternative 2 is what they proposed, and what was ultimately chosen (https://parkplanning.nps.gov/document.cfm?documentID=83442). But the public comments on that page are worth reading too, with anglers and other community members wanting more access, more boat launches, giving the land back to the state, etc.
This project ultimately resulted in a "FONSI", a "Finding of No Significant Impact", which means the agency thought that it wasn't a big enough deal to warrant a full investigation. The environmental assessment they did was just a preliminary review; if they had found significant impacts, it would've turned into a much longer investigation, like this 382-page environmental impact statement for another seashore (https://parkplanning.nps.gov/document.cfm?parkID=358&project...).
By contrast, even at 30-some pages, this is a pretty typical EA. The agency has to be relatively thorough and check a bunch of boxes, or they can risk getting sued by environmental watchdogs, local activists, property owners & developers, etc.
Aaaaaaaaanyway, I hope I don't sound like I'm lecturing here. I don't have a dog in this race and I don't know all the facts, I just wanted to somewhat briefly explain the long and convoluted process that is NEPA (the National Environmental Policy Act), which is a super important piece of law that the government is absolutely terrible at explaining or marketing. Even this overview flowchart is super complicated, and the actual process is waaaaaay more complex: https://www.fs.usda.gov/emc/nepa/revisions/includes/docs/NEP...
For example, each stage of this process usually has a public comment period, which is the "official" way for the public to provide its input on projects. Sometimes they get a lot of attention, but other times they fly totally under the radar. I wish the government were more invested in publicizing these things and getting the public to be aware of them (such as mandatory notifications via email or social media or SMS or whatever). But even when the public does provide feedback, the agency isn't really obligated to agree with them, merely to acknowledge and respond to them. In this case, the public comments I linked to above explicitly requested more boat launches, other dredging options, etc., and the NPS explained its rationales about why it didn't do those things, why those things are out of scope for its proposed projects, etc.
It's a lot of red tape and bureaucratic language that basically boils down to "Thanks for your comment. We're going to do this anyway." And that, IMO, is a separate failure of the current law: there is not really an avenue for direct democratic participation in these processes. You can scream at them all you want but ultimately it's not your call. And that's how we end up with vigilante fishermen who take matters into their own hands.
NEPA was a groundbreaking law in its day that helped protect a lot of our public lands that otherwise would've been irreparably harmed or destroyed outright. But it's also 50+ years old now and probably in need of some updating and streamlining and more opportunities for public participation. But that's the sort of unsexy infrastructure and resource discussion that most hotshot politicians don't want to focus on, instead arguing about the latest hot-button culture war issues.
Man, I wish people invested as much emotion into these things as, say, bathrooms or movie casting. By and large people just ignore our public lands management until something suddenly changes that they don't like (even though it's often been planned for years if not decades, again, usually completely under the radar just because the governments are so bad at marketing and publicizing).