A liner along the bottom of the Reflecting Pool in Washington DC was cut with a sharp knife or razor earlier this month, an official at the National Park Service has said.
Frank Lands, deputy director of operations for the park service, said in a court filing on Thursday that US Park Police had responded to a report of an incident on 9 June regarding the pool's liner, which caused damage to the foam sealant that had been installed as part of a recent multi-million dollar rehabilitation project.
Earlier this week, US President Donald Trump blamed vandals for "a 300-foot-long gash" and accused someone of putting fertiliser in the water.
The president was pressed by CBS News during an interview, external for evidence of the slit, which Trump said would be provided in court.
In the recent court filing, Lands said a US Park Police report indicated damage "including a caulk over the foam sealant that was cut with a sharp knife or razor and destruction of delaminating surface material."
It also detailed that "approximately 70 fence post tops were thrown into the pool".
However, it does not say when exactly the damage occurred and does not identify anyone who might have been involved.
The statement in the court filing is part of a lawsuit filed by a nonprofit organisation seeking to stop the Trump administration's work on the site.
It is also the first public record detailing how the pool may have been damaged after work on the project was completed.
Renovations to the The Lincoln Memorial Reflecting Pool started in April and went on for two months, under Trump's request, ahead of the 250th anniversary of the United States.
"The 2,000-foot-long basin was drained" and "a tinted polyurea liner" was installed in the pool to "waterproof and protect the concrete pool surface", the NPS outlined in its statement.
But after being refilled with water, the pool was plagued by an algae bloom and developed issues with the deep blue paint that was added to its bottom.
Five people have been arrested for vandalism in connection with the Reflecting Pool, and five others were issued federal citations, according to US Park Police.
The NPS plans to drain the pool once more after Independence Day celebrations on 4 July to "conduct repairs, including assessments and repairing any damage to the lining", Lands said.
The pool, which was built in the 1920s and stretches 2,030ft (619m) between the Lincoln Memorial and the Washington Monument, has long suffered from leaks, structural deterioration, faulty pipes, algae growth and bird droppings.
