Source: National Weather Service

Conditions are building for a rough spring flooding season in the Midwest that could disrupt the transportation of many commodities including agricultural fertilizers, the National Weather Service (NWS) said on Thursday.

"A deep snowpack and recent heavy rains have elevated the spring flood threat in parts of the Midwest," said NWS spokesman Pat Slattery from his office in Kansas City, Mo., where the service keeps an eye on the upper Mississippi river watershed.

Flooding could rival the high water levels experienced in 2006, and possibly 1997, Slattery said.

The transportation of bulk fertilizers such as ammonia, potash, phosphate and urea by barge, rail and truck can be severely hampered by flood waters, which can close locks, bridges, rail lines, and roads.

According to the latest data available, 1.7m/tonnes of anhydrous ammonia was moved by barge in the US in 2007, The Fertilizer Institute spokesperson Kathy Mathers said.

The Illinois River crested earlier this week at Meredosia, Ill., where Transammonia and Agrium have riverside nitrogen storage facilities, but potential logistics problems loom elsewhere in the Midwest.

Winter frost had yet to melt out of the ground in the northern states, according to the NWS. Any significant rain in these areas would cause flooding.

A massive late winter storm this week affected Montana, the Dakotas and Minnesota, exacerbating the potential for flooding in the Missouri and Mississippi watersheds.

The Red River, which flows between North Dakota and Minnesota, began to flood this week with a potential crest above historic levels. The Red river flows north into Canada where its waters eventually reach Hudson Bay.

Mathers said fertilizer retailers in the Red River Valley report that it was too cold and the ground too frozen for the flooding to affect any application activity.

"Retailers were busy on Thursday taking steps to keep their inventory out of harms way," Mathers said.

Forty miles to the east in Minnesota, a continental divide sends water flowing into the Mississippi river system where flooding is expected to occur over the next several weeks.

About half-way down the Mississippi from St. Paul to New Orleans, the big river is already near flood stage at Hannibal, Missouri, with minor flooding occurring at Hardin, according to the NWS Advanced Hydrologic Prediction Service.

The NWS North Central River Forecast Center said that the greatest chance of major flooding along the Mississippi will occur during the period of April 14-28.

Slattery said the area around St Louis, where the Mississippi River is joined by the Missouri and Ohio rivers, and southward could be in danger of severe flooding in 2009.

"We are looking at a situation with all the ingredients for near record flooding in the Midwest," said NWS director Jack Hayes.

"Sudden snowpack melts due to warm temperatures or a heavy rain could further complicate the flooding on the northern plains," Hayes said.