The thunder of artillery echoes night and day over the mighty Dnipro River as it winds its way through southern Ukraine. With Russian and Ukrainian forces squared off on opposite banks, fighters have replaced fishermen, surveillance drones circle overhead and mines line the marshy embankments.

Carving an arc through Ukraine from its northern border to the Black Sea, through Kyiv, Zaporizhzhia and Kherson, the Dnipro shapes the country’s geography and economy, its culture and its very identity. And now it helps define the contours of battle — as it has for millenniums, a barrier and a conduit to warring Scythians, Greeks, Vikings, Huns, Cossacks, Russians, Germans and many more.

Visiting towns and villages along the Dnipro a year after Russia’s full-scale invasion and ahead of a much-anticipated Ukrainian counteroffensive, Nicole Tung, a photographer for The New York Times, traveled a path marked by hope and horror, joy and sorrow.

The Dnipro has always been Ukraine’s great natural engine, supplying water, transport, power — and food. The fishing industry is crucial to Ukraine’s domestic food market, with 80 percent of the annual catch coming from the Dnipro and its reservoirs, according to the Ukrainian Nature Conservation Group.

But fish stocks have been decimated by the war. After Russian forces damaged the Nova Kakhovka dam, the river dropped by about 1.5 meters (five feet) over the winter, Ihor Syrota, the head of the state company that manages Ukraine’s hydropower plants, said in an interview. The water level hit a 30-year low — too low to sustain the fish population.

Mykola Derebas, 54, a fisherman for over three decades, lost his job at the start of Russia’s full-scale invasion. He cannot even catch enough fish now to feed his own family in the town of Malokaterynivka, near the city of Zaporizhzhia.

“Not being able to go fishing is almost like when a person loses their leg,” Mr. Derebas said in late January. “All I hoped for when the war started was for it to be over, but I don’t see how it will be finished anytime soon. All we can do is sit and wait.”

The dams along the Dnipro were once mighty symbols of Soviet prowess. “Communism is Soviet power plus the electrification of the whole country,” Vladimir Lenin famously declared in 1920.

In 1932, Soviet engineers completed work on what was then the largest dam ever built in Europe, near the city of Zaporizhzhia — one in a cascade of dams and hydroelectric plants on hundreds of miles of the Dnipro, from north of Kyiv to Nova Kakhovka. In the 1980s, their successors built the Zaporizhzhia Nuclear Power Plant, Europe’s largest atomic power station, which now poses a particular risk as it lies in the line of fire.

Over the past year, Moscow has repeatedly bombed the Dnipro power stations that Soviet leaders so proudly promoted as the key to prosperity.

While Ukraine is working to restore water levels on the Dnipro, they remain far below normal.

“Of special concern are large reservoirs along the Dnipro River, which are critical for energy production, cooling of nuclear power plants, sustaining agriculture and seasonal flow regulation,” said a study published in the scientific journal Nature in March.

The Zaporizhzhia nuclear plant is under Russian occupation, and British military intelligence recently warned that Russian forces had “established sandbag fighting positions on the roofs of several of the six reactor buildings,” which “increases the chances of damage” to the plant.

While the situation there has sparked international alarm, other dangers have gotten less attention.

One of the Soviet Union’s largest processing plants for nuclear fuel sits near the river, outside the city of Dnipro — long neglected, though it holds an estimated 40 million tons of radioactive waste, according to a 2020 report by the Bellona Foundation, a Norwegian environmental group. Scientists have warned of an environmental catastrophe if the facility is shelled and waste contaminates the river.

The conflict has already wrought untold damage.

The study in Nature showed how in the first months of the war alone, Russian attacks on wastewater treatment facilities resulted in widespread pollution of waters. At the same time, the rivers and irrigation channels that both militaries use as natural fortifications “have also become a burial place for military objects,” like ammunition that can leak heavy metals and toxic explosives, with impacts that may last for decades.

President Volodymyr Zelensky often quotes Taras Shevchenko, Ukraine’s most famous poet, to rally his nation. In his 1845 poem “Testament,” a battle cry against Russian subjugation, Shevchenko wrote that he would not go to God until the Dnipro “delivers to the sea the spilled blood of Ukraine’s enemies.”

Many Ukrainians would support that sentiment, but even during some of the war’s darkest moments, Ukrainians have also found ways to celebrate life. That is particularly true in cities like Dnipro that have not been at the heart of the fighting, though they have suffered bombings and blackouts, and have given refuge to people fleeing horrors elsewhere.

This winter, young actors and dancers from the Dnipro Academic Opera and Ballet Theater performed “Sorochinsky Fair,” an operetta based on a story by the Ukrainian writer Nikolai Gogol. It is a love story centered on overcoming evil spirits, mixing Ukrainian folk traditions, crafts and humor.

The war rages on along the river, scarring towns and villages, and Russia has often directed its fire at civilian areas, a reminder that when armies clash, civilians often pay the highest price.

As the Germans invaded in 1941, Stalin ordered the destruction of the great Soviet dam in Zaporizhzhia, flooding a vast area and killing anywhere between 20,000 and 100,000 people, according to military historians. In 1943, the Germans blew up the dam again, trying to slow the Soviet advance in the Battle of the Dnipro, one of the largest engagements of the war.

Last fall, Ukrainian forces drove the invaders from the west bank of the lower Dnipro, including the city of Kherson and the farms and hamlets around it, but the Russians have continued to bombard the area. For Inna, 57, and her husband Mykola, 63, who live near the city of Kherson, that means days are centered around getting the cooking and cleaning done before noon, when the sound of incoming Russian artillery means it is time to move to their food cellar.

“I don’t want to leave this home because I can’t, mentally,” Inna said this winter. “These are my walls, and if it’s meant to be, it will be.”

The Ukrainian authorities have ordered all residents on the river’s west bank not to leave their homes this weekend, as Russian shelling of the region has intensified ahead of the looming Ukrainian counteroffensive. On a single day this week, Russian shelling killed at least 23 civilians.

Rivers can “tell the story of a nation’s history and a people’s experience,” Roman Cybriwsky observed in his authoritative chronicle of the Dnipro, “Along Ukraine’s River.”

The Dnipro tells a tale with “a plentitude of national sorrow,” he wrote, but also reveals moments “uplifting and joyous,” an observation that holds true even in wartime. In areas out of range of Russian artillery, the Dnipro remains a vital part of Ukrainian life. People flock to its banks to find moments of solace and reprieve.

But everywhere, the savage toll of wars past and present is visible. The burial mounds of Scythian fighters killed thousands of years ago can be found near memorials to soldiers and civilians killed in World War II. At a graveyard outside the city of Dnipro, there is a section for soldiers killed in eastern Ukraine in 2014, when Russia invaded Crimea.

Since Russia’s full-scale invasion last year, the cemetery continues to grow.

Nicole Tung, Evelina Riabenko and Andriy Kalchenko contributed reporting.