*Changed the way the Endangered Species Act is applied, making it more difficult to protect wildlife from long-term threats posed by climate change.
*Overturned a ban on the use of lead ammunition and fishing tackle on federal lands.
*Overturned a ban on the hunting of predators in Alaskan wildlife refuges.
*Amended fishing regulations for a number of species to allow for longer seasons and higher catch rates.
*Withdrew proposed limits on the number of endangered marine mammals and sea turtles that can be unintentionally killed or injured with sword-fishing nets by people who fish on the West Coast. (In 2018, California issued a state rule prohibiting the use of the nets the rule was intending to regulate.)
*Rolled back a roughly 40-year-old interpretation of a policy aimed at protecting migratory birds, potentially running afoul of treaties with Canada and Mexico.
*Overturned a ban on using parts of migratory birds in handicrafts made by Alaskan Natives.
*Opened nine million acres of Western land to oil and gas drilling by weakening habitat protections for the sage grouse, an imperiled bird with an elaborate mating dance. An Idaho District Court injunction blocked the measure.
*Proposed ending an Obama-era rule that barred using bait to lure and kill grizzly bears, among other sport hunting practices that many people consider extreme, on some public lands in Alaska.
*Proposed relaxing environmental protections for salmon and smelt in California’s Central Valley in order to free up water for farmers.
*Scaled back pollution protections for certain tributaries and wetlands that were regulated under the Clean Water Act by the Obama administration.
*Revoked a rule that prevented coal companies from dumping mining debris into local streams.
*Withdrew a proposed rule aimed at reducing pollutants, including air pollution, at sewage treatment plants.
*Withdrew a proposed rule requiring groundwater protections for certain uranium mines.
*Proposed a rule exempting certain types of power plants from parts of an E.P.A. rule limiting toxic discharge from power plants into public waterways.
*Proposed allowing the E.P.A. to issue permits for federal projects under the Clean Water Act over state objections if they don't meet local water quality goals, including for pipelines and other fossil fuel facilities.
*Proposed extending the lifespan of unlined coal ash holding areas, which can spill their contents because they lack a protective underlay.
*Proposed a regulation limiting the scope of an Obama-era rule under which companies had to prove that large deposits of recycled coal ash would not harm the environment.
*Proposed a new rule allowing the federal government to issue permits for coal ash waste in Indian Country and some states without review if the disposal site is in compliance with federal regulations.
*Proposed doubling the time allowed to remove lead pipes from water systems with high levels of lead.
*Repealed an Obama-era regulation that would have nearly doubled the number of light bulbs subject to energy-efficiency standards starting in January 2020. The E.P.A. also blocked the next phase of efficiency standards for general-purpose bulbs already subject to regulation.
*Allowed coastal replenishment projects to use sand from protected beaches.
*Limited funding environmental and community development projects through corporate settlements of federal lawsuits.
*Announced the intent to stop payments to the Green Climate Fund, a United Nations program to help poorer countries reduce carbon emissions.
*Reversed restrictions on the sale of plastic water bottles in national parks designed to cut down on litter, despite a Park Service report that the effort worked.
*Ordered a review of water efficiency standards in bathroom fixtures, including toilets.
*Proposed limiting the studies used by the E.P.A. for rule-making to only those that make data publicly available. (Scientists widely criticized the proposal, saying it would effectively block the agency from considering landmark research that relies on confidential health data.)
*Proposed changes to the way cost-benefit analyses are conducted under the Clean Air Act, Clean Water Act and other environmental statutes.
*Proposed withdrawing efficiency standards for residential furnaces and commercial water heaters designed to reduce energy use.
*Created a product category that would allow some dishwashers to be exempt from energy efficiency standards.
*Initially withdrew then delayed a proposed rule that would inform car owners about fuel-efficient replacement tires. (The Transportation Department has scheduled a new rule-making notice for 2020.)