Kherson, Ukraine — Authorities rushed drinking water to areas flooded by a collapsed dam in southern Ukraine on Wednesday as they managed a growing humanitarian and ecological disaster along a river that forms part of the front line in the 15-month war.

The collapse of the Kakhovka hydroelectric dam and emptying of its reservoir on the Dnieper River added to the misery the region has suffered for more than a year from artillery and missile attacks.

With humanitarian and ecological disasters still unfolding, it is already clear that tens of thousands of people have been deprived of drinking water, many are homeless, crops are ruined, land mines have been displaced, and the stage is set for long-term electricity shortages.

Some residents of Russian-occupied areas hit by high water complained that help was slow in arriving, with some stranded on roofs and streets passable only by boat in scenes more like natural disasters than wars. Others refused to leave.

About 3,000 people have been evacuated from both the Russian and Ukrainian-controlled sides of the river, officials said, with the true scale of the disaster yet to emerge in an affected area that was home to more than 60,000 people. Russian-appointed authorities in the occupied parts of the Kherson region reported 15,000 flooded homes.

The dam and reservoir, essential for fresh water and irrigation for a huge area of southern Ukraine, lies in the Kherson region that Moscow illegally annexed in September and has occupied for the past year. The reservoir is also critical for water supplies to the Crimean Peninsula, which Russia illegally annexed in 2014.

Ukraine holds the Dnieper’s western bank, while Russia controls the low-lying eastern side, which is lmore vulnerable to flooding.

The high water could wash away this season’s crops, while the depleted Kakhovka reservoir would deny adequate irrigation in the years ahead.

A day after the dam’s collapse, it remained unclear what caused it, with both sides blaming each other. Some experts said it might have been due to wartime damage and neglect, although others argued that Russia might have destroyed it for military reasons. Either way, concluded analyst Michael Kofman, “Russia is responsible, either by virtue of action or by virtue of the fact that it controlled the dam.”

“It’s going to lead to lasting damage to agriculture, provision of drinkable water. And it’s going to wipe out entire communities,” Kofman — who is with the Center for Naval Analyses, a U.S. research group — told the “PBS NewsHour.”

Many residents had long ago fled the region due to the fighting, but others stayed, making it hard to determine how many people remain at risk in an area where hundreds of thousands lived before Russia’s February 2022 invasion.

Ukraine President Volodymyr Zelenskyy met with officials on how to provide drinking water to residents, as well as assess damage to wetlands, farms and other property from what he called “a crime of ecocide.”

“The destruction of the dam and the reservoir is a manmade strike on the environment, after which nature will have to recover for decades,” Zelenskyy said in English in a video posted on YouTube. He said it was impossible to predict how much of the chemicals and oil products stored in flooded areas will end up in rivers and the sea.

Ukraine’s agriculture ministry warned, “The fields in the south of Ukraine next year can turn into deserts.”

Zelenskyy accused Moscow-installed officials in occupied areas of failing to respond adequately to the emergency.

Those officials said they evacuated fewer than 1,300 people in an area where at least 22,000 people were said to have been affected. That compared with about 1,700 evacuated on the Ukrainian side where the population was reportedly around 42,000.