The United Nations secretary general for humanitarian affairs said in a series of UN reports on Friday that Ukraine’s humanitarian crisis has been made severely worse by the Kakhovka Hydroelectric Power Plant’s destruction. The UN’s top official in Ukraine, Denise Brown, says that immediate needs are now “huge.”

In his statement to the UN, Secretary General for Humanitarian Affairs and Emergency Relief Coordinator Martin Griffiths says that the disaster is “potentially the most significant incident of damage to civilian infrastructure since the start of the invasion.” While he says that there are many humanitarian efforts for relief and aid, it may be difficult to deliver assistance to some areas, and the flooding makes life “intolerably harder for those already suffering from the conflict.”

The UN aid coordination office (OCHA) released a statement that flooding will continue for “at least a week,” impacting at least 17,000 people. That number could rise to an estimated 40,000 people. Stagnating water is increasing the risk for waterborne diseases such as cholera, and water is being contaminated with sewage, heavy oil, pesticides and other harmful chemicals, posing a major health hazard. Officials have also expressed concern about mines floating downstream.

Griffiths cited international humanitarian law which outlines that installations such as dams must receive special protection, as their destruction can result in severe loss for the civilian population. International law also creates special protections for water during times of war.

The High Representative Borrell and Commissioner Lenarcic are blaming Russia for the dam’s destruction, stating that such an attack may constitute a violation of international humanitarian law. According to a joint statement, the resulting downstream flooding is “putting at risk the lives of hundreds of thousands of civilians in over 80 settlements,” further exacerbating the humanitarian situation. It states that dropping water levels is affecting access to “critical cooling water for the reactors of the Zaporizhzhia Nuclear Power Plant.”

In terms of long term effects, UN officials noted that the dam’s destruction could have a major impact on water and energy supplies, environmental contamination and result in the destruction of farmland and livestock.