A new floating laboratory onboard a boat on the Potomac River is keeping tabs on the water quality that flows through the nation's capital and surrounding area. A local environmental group, the Potomac Riverkeeper Network, is collecting water samples at several sites to measure the amount of bacteria that cause pollution. As VOA's Deborah Block reports, the data will be used to help clean up polluted areas in the future and is already informing the public when it is safe to swim in the river.