In 2009 the Chesapeake Bay Foundation (CBF) filed suit against EPA for its failure to finalize a total maximum daily load (TMDL) ruling for the bay, pursuant to the Clean Water Act. The TMDL would restrict water pollution from farms, land development, power plants and sewage treatment plants. EPA, which had been working with the states on various components of the TMDL since the 1980s (e.g. water quality criteria, standards for individual tributaries, improvements in data gathering and modeling techniques), agreed to settle the lawsuit and issued its TMDL for nitrogen, phosphorus and sediment pollution on December 29, 2010. This was the largest, most complex TMDL document that EPA had issued to date. The TMDL was challenged in litigation by the agriculture and construction industries, but EPA's document was upheld by the courts.
In 2020 the CBF filed another lawsuit against EPA for its failure to require the states of New York and Pennsylvania to comply with their TMDL goals and reduce pollution in the bay.
EPAs 2010 TMDL document requires all states in the bay watershed region to develop detailed implementation plans for pollutant reduction. The states have been developing their plans for years, in many cases building upon restoration projects that they had initiated before EPAs TMDL was finalized. These plans are long and complex, involving regular consultation with many stakeholders (i.e. governments, industry, agriculture, citizen groups). The plans include multiple milestone goals for project initiation or continued progress in water quality, through the use of pollution control upgrades (such as at sewage treatment plants) and more widespread utilization of various best management practices (BMPs). The BMPs are designed for specific sites to control pollution from nonpoint sources, principally agriculture, land development and urban runoff. For example, a farmer may install vegetated stream buffers along a stream bank to reduce runoff of sediment, nutrients and other pollutants. A land developer may install stormwater management facilities such as infiltration basins or constructed wetlands during the construction of housing or commercial buildings.
In 2011 both Maryland and Virginia enacted laws to reduce the effects of lawn fertilizer use, by restricting nitrogen and phosphorus content. The Virginia law also banned deicers containing urea, nitrogen or phosphorus.
Installation of stormwater management facilities is already a requirement for most new construction projects in the bay region, under various state and local government requirements. These facilities reduce erosion and keep sediment and other pollutants from entering tributaries and the bay. However retrofitting such facilities into existing developed areas is often expensive due to high land costs, or difficult to install among existing structures. As a result, the extent of such retrofit projects in the bay region has been limited.