MINNEAPOLIS (AP) — The U.S. is falling short of its goals to cut Mississippi River pollution and shrink the dead zone it creates in the Gulf of Mexico.

Speaking in Minneapolis on Tuesday, Environmental Protection Agency officials said states in the river’s watershed need to accelerate efforts to cut pollution from farm field runoff and discharges from sewage treatment plants.

The Gulf’s dead zone, an area of depleted oxygen that’s largely devoid of marine life, was the size of Connecticut this summer. In 2008, an EPA-led task force set a goal of reducing it to 5,000 square kilometers — still larger than Rhode Island — by 2015.

Nancy Stoner, the EPA’s acting assistant administrator for water, said her agency and river states have worked together to come up with strategies, but that progress is going more slowly than they’d hoped.

“It’s about three times the size we’re looking for in terms of our ultimate goal,” said Stoner, who co-chairs the task force. “It has not appreciably shrunk yet.”

Each of the 12 states along the river has its own plan to help reach the overall goal. The Minnesota Pollution Control Agency will issue a draft of its updated plan next month and take public comments on it.

MPCA Assistant Commissioner Rebecca Flood previewed Minnesota’s plan for state and federal regulators, saying that within 12 years, the state hopes to reduce nitrogen runoff from farm fields, urban streets and water treatment plants by 20 percent. Phosphorus, another nutrient that primarily comes from agricultural fertilizers and soil runoff, would be reduced by 35 percent.

High levels of nitrates and phosphorous lead to excessive plant and algae growth, which doesn’t provide enough oxygen to support aquatic life.

Iowa Secretary of Agriculture Bill Northey, the other task force co-chair, said states are just beginning to tackle nitrate pollution from farm runoff. He said it isn’t as simple as changing fertilizer rates because nitrogen is also in crop residue and organic matter.

Planting cover crops that absorb nitrogen, such as alfalfa, is one way farmers can reduce nitrate pollution. But farmer participation is voluntary, and Stoner said the EPA doesn’t have the authority to make it mandatory.

Some environmental groups have criticized the EPA for not doing more. Last week, a federal judge in New Orleans told the agency it has six months to decide whether to set standards for nitrogen and phosphorous pollution or explain why they’re not needed.

Trevor Russell, program director for Friends of the Mississippi River, said the EPA’s goals are good, but changing land management practices across millions of acres will be a staggering task without federal funding or mandatory regulations.