The Lincoln Memorial seen from the reflecting pool.
The National Park Service is trying to remove a thick layer of green algae from the reflecting pool in front of the Lincoln Memorial.
The algae began to cover one end of the reflecting pool less than a month after a $34 million overhaul was completed.
The recent two-year reengineered project was designed to use river water from the Tidal Basin instead of city drinking water. The system is supposed to filter and circulate the water to keep it cleaner than it was in past years.
A Park service spokesperson says the new water system is complex and needs to be fine-tuned. As a result workers are boosting the amount of ozone in the water to in an effort to improve the quality.