Washington Monument
US capital's sustainability plan
Washington DC plans to capture the majority of its rainfall for reuse or filtration as part of a bid to become the most liveable sustainable city in the US.
The ambitious target, which it hopes to achieve by 2032, will see the US capital aim to use three-quarters of its landscape to capture storm water, either to reuse it or to allow it to filter through the earth instead of putting pressure on storm water infrastructure. In this way, it is hoped to alleviate the flash flooding and surges after storms that are said to be responsible for up to 90% of river pollution in the city.
The target is part of the Sustainable DC 2032 plan, which covers areas like climate change mitigation and adaption, job creation and healthcare. 
The city has created the first private market for trading storm water retention credits that it hopes will encourage the building of green infrastructure. Sustainable DC estimates that $14.3 million can be saved each year if rainwater is captured from rooftops and reused.
Among Sustainable DC's other ambitions is a scheme to retrofit the entire city's existing commercial and multi-family buildings to net zero energy standards. It is hoped to cut energy use across the city by 50% and to draw half of Washington's energy needs from renewable sources. The city's power needs are already purchased from green energy companies.

Other targets include: 

- Increasing the area of wetlands surrounding local rivers by 50%.
- Covering 40% of the city with a tree canopy.
- Providing parkland or natural space within 10 minutes' walk of all residents.
- Reducing car commuting to 25% of total.
- Decreasing total water use by 40%.

The package of measures comes as the city's population has started to grow again after decades of decline and is part of a long-term goal to make it a more attractive place for new residents as well as existing inhabitants. Sustainable DC's management believes that "in just one generation - 20 years - the District of Columbia will be the healthiest, greenest, and most liveable city in the United States."