A protest letter was sent days before the 20th anniversary of Katrina, which caused catastrophic flooding in New Orleans and devastating destruction along the Gulf Coast in August 2005, claiming the lives of more than 1800 people.
The letter, signed by 35 named employees at the Federal Emergency Management Agency, was a rare airing of internal dissent.
It said the agency's current leaders, including Homeland Security Secretary Kristi Noem and acting agency director David Richardson, lacked the qualifications to manage natural disasters and were eroding its ability to respond to hurricanes and other emergencies.
Noem's requirement that she review all contracts and grants over $US100,000 ($A154,116) "reduces FEMA's authorities and capabilities to swiftly deliver our mission," the letter states.
It asks Congress to make FEMA an independent cabinet-level agency free from interference from the Department of Homeland Security and to protect agency employees from politically motivated firings.
This was necessary "to prevent not only another national catastrophe like Hurricane Katrina, but the effective dissolution of FEMA itself".
Daniel Llargues, the acting agency press secretary, said the organisation is "committed to ensuring FEMA delivers for the American people".
He said FEMA has been bogged down by red tape and inefficiencies and the Trump administration "has made accountability and reform a priority".
Roughly 2000 FEMA employees, or a third of its workforce, have left the agency this year through firings, buyouts or early retirements.
The Trump administration also plans to cut about $US1 billion ($A1.5 billion) in grant funding, affecting its emergency management programs.
The letter was also delivered two months into the US hurricane season and at a time when President Donald Trump had said he wanted to drastically cut the size and mandate of FEMA.
This would leave much more of the burden of responding to natural disasters to individual states.
Katrina was one of the worst natural disasters in US history, in part because of a breakdown of leadership and response at the city, state and federal levels.
Congress passed the Post-Katrina Emergency Reform Act in 2006 to give FEMA more responsibility and to put in place safeguards to mitigate against another failed response.
The letter warns that the Trump administration is undoing those reforms and sending FEMA back to pre-Katrina levels by cutting funding, reducing disaster recovery and training programs, and hampering its ability to act quickly because of stringent new oversight policies.
