Federal and state environmental relations

There are benefits to leaving environmental regulation both to the federal government to the states.For example, wildlife conservation is much more of a concern for Alaska than for New York. New York, however, has much bigger air and light pollution issues than Alaska.
Because of all of these factors, it almost never ends up being an either/or situation in terms of environmental regulation. One of the few areas that is under complete federal control is the storage and disposal of commercial-level nuclear waste, most likely because the consequences of not properly dealing with it are more dire than for most environmental concerns. States have greater regulatory freedom for areas like air and water pollution, presumably because they are not considered to be as high-stakes as nuclear waste. 
Formation of policy.
Prior to the late 1970s, nearly all environmental policy was at the state and local level. Federal environmental regulation addressed the federal government itself, rather than states, consumers, or industry. This all changed with a flurry of environmental legislation in the early 1970s. Currently, most federal environmental laws grant both expansive regulatory authority to federal agencies, as well as authorize states to implement plans outlined in federal laws. This model is often called "cooperative federalism.".
States Shaping Federal Policy.
Relationships between State and Federal parties often shape environmental laws and policy. States can directly shape federal policy in the way states choose to enforce, or not enforce, environmental regulation. Federal regulation of nonpoint source water pollution is often cited as weak, in part because localities often lack the incentive to enforce federal regulations, and federal enforcers do not have the authority to countermand state decisions. In areas where the federal government cannot directly intervene, state and local governments have a very strong hand in shaping the practical effect of federal regulation.
States often serve as testing grounds for policies which may be adopted as federal law or policy later. This idea, often called "Laboratories of democracy," was articulated by Louis Brandeis in dissent to a 1932 supreme court ruling. If states are left a free hand to try different forms of regulation, the relative merits of each approach will be easier to identify. States often adopt successful regulations from other states as well. One example is treatment of electronic waste. Currently, 18 states and New York City have enacted laws requiring the recycling of electronics at the end of their useful lives., whereas the Federal programs do not treat electronic waste different from other solid waste. Some states have adopted legislation similar to existing legislation in other states, and Congress has recently considered several bills to regulate e-waste, perhaps as a result of pioneering state regulation.
States have also used litigation to force federal regulation. A "deluge" of litigation has forced federal agencies, and the EPA in particular, to adopt more aggressive policies. Nowhere is this trend more clear than with greenhouse gas emissions. In the absence of federal climate change regulation, states have brought public nuisance suits against carbon emitters and the EPA. In Massachusetts v. EPA, a group of states succeeded in compelling EPA to promulgate rules to regulate C02 emissions under the clean air act States have spurred federal action by bringing suit against emitters directly, such as when California sued General Motors and a number of states sued power companies, both over carbon emissions.
Federal Policy Shaping State Policy.
Federal regulation often acts as a signal to states. States may perceive this signal to mean more stringent regulation is necessary. Alternately, states may understand federal regulation to be a maximum standard or states may believe federal legislation crowds out state action. In some cases, states have reacted to federal environmental policy by enacting legislation to limit state agencies from enforcing standards more stringent than federal standards. States may also adopt radically different policies as a result of perceived weakness in federal legislation.
Lastly, limits on state and federal power have often shaped environmental regulation. Federal law may preempt state legislation in issues of interstate commerce or navigable waters. Federalism doctrine limits federal power as well. For example, federal policy regarding non-point water pollution is typically subsidies to states with plans to regulate these emissions, in part because of the serious question as to whether the federal government can regulate interstate land use, as it applies to pollution.
Federalism.
Overview.
Since environmental issues are so complex, it is often lawmakers' opinion that the regulations covering these issues should be broad, all-encompassing and adjustable as new information is made available. Environmental issues are often regional or nationwide and this is reflected in regulation. Some problems are addressed at the federal level or the state level, while others are regulated by both.
Under the 10th amendment, any area over which the federal government does not have authority is under state authority. Federal regulation preempts state and local legislation under the supremacy clause when the two conflict, and under the Dormant Commerce Clause when federal legislation is silent and states seek local protectionism. In many situations of environmental regulations, state and federal governments have Concurrent powers, where each government is permitted to have its own regulation.
When the federal government would like state governments to take certain actions, the federal government may use conditional spending provisions, offering money if states take the desired actions. While some link must exist between the federal money and the desired action, the links may be tenuous. The federal government may not coerce state action or commandeer state resources to take certain actions. 
However, when the federal government has authority to take the desired actions directly, it may use conditional preemption. Conditional preemption is where the federal government allows states to take the desired actions, and if states do not satisfy federal demands, the federal government steps in and takes over enforcement. Both the Clean Air Act and the Clean Water Act contain conditional spending provisions.
Enforcement.
Federal Involvement.
Many environmental laws establish federal standards as the minimum criteria needed to be met in order to ensure state compliance. These include the SDWA, RCRA, CAA, and CWA. The notion is that as long as states meet the federal standards, the EPA will not step in. However, there are fundamental differences regarding how this is enforced.