SIOUX CITY (AP) – Sioux City is looking to get ahead of new state wastewater treatment regulations – the latest in ever-changing environmental rules that have cities struggling to keep up.

Sioux City is among several Iowa municipalities studying how to add phosphorus and nitrogen removal to their wastewater treatment plants before the guidelines become mandatory. Any changes in Sioux City would come after $73 million was spent updating the plant to meet state guidelines in 2011.

The plant treats residential sewage and industrial wastewater from the metro area and releases it into the Missouri River.

The requirements would be part of Iowa’s Nutrient Reduction Strategy – an effort to reduce phosphorus and nitrogen pollution entering the Mississippi River Basin by 45 percent.

Water pollution has caused an oxygen-deficient dead zone in the Gulf of Mexico, prompting the U.S. Environmental Protection Agency to require 12 states along the Mississippi River Basin to implement environmental changes.

Those states are Iowa, Louisiana, Mississippi, Kansas, Tennessee, Kentucky, Minnesota, Wisconsin, Indiana, Ohio, Illinois and Missouri.

The Sioux City Council voted 4-1 on Dec. 10 to approve a $29,600 study looking at the cost of adding better phosphorus removal to its wastewater treatment plant. The plant already removes nitrogen.

Sioux City does not have to conduct a study now, but wastewater treatment plant director Jay Niday said the data is needed if the city wants to have input on the Iowa Department of Natural Resources’ pending guidelines.

“This is something we are going to have to do anyway,” he said. “We want to be involved in these discussions, so we need this data. We could potentially influence these discussions and reduce our cost.”

Outgoing Councilman Tom Padgett, who voted for the study, said the Iowa League of Cities will address the proposals as a group.

“Phosphorus removal could be expensive,” he said. “We are trying to work with the state and the league to hopefully come to an agreement on standards that are acceptable to the Environmental Protection Agency and Department of Natural Resources.”

Voluntary vs mandate

Iowa has not set a timeline yet for when upgrades to remove phosphorus would have to be implemented, or how much of a reduction would be required at individual plants.

Mayor Bob Scott, who cast the lone no vote on Sioux City’s study, opposed the study because he fears getting too far ahead of the game could mean the state expects changes to come to Sioux City quicker.

Scott added it’s frustrating to see that the state plans to mandate another plant update two years after the city poured $73 million into the facility to meet state requirements.

“We already spent about $73 million on that plant and now they want more changes,” Scott said. “They keep moving the bar, and we’re not even the main problem.”

Scott also raised concerns that agriculture – the primary source of phosphorus and nitrogen pollution in Iowa – faces voluntary regulations while municipalities face mandatory changes.

The Department of Natural Resources says 80-90 percent of phosphorus and nitrogen pollution comes from non-point source locations. Most of that is believed to be fertilizer runoff from farm fields.

While guidelines for farmers are not mandatory, environmental and agriculture leaders have said they’re really not voluntary.

Department of Natural Resources spokesman Adam Schnieders said the goal behind voluntary agriculture regulations is that farmers know mandatory policies will come down next if they do not take action to curb fertilizer runoff into nearby waterways.

The state is also trying to work with cities to find out what changes they can afford to make, and how long it will take to upgrade treatment plants.

Ultimately, the state wants to ensure changes are affordable and realistic.

Iowa has 102 municipal wastewater treatment plants that discharge at least 1 million gallons of water a day.

Sioux City’s plant discharges between 16 million and 28 million gallons a day.

“What can you do and what timeline will work for you given everything else that’s also going on?” Schnieders asked. “We know there are challenges.”

Niday said the state’s willingness to work with municipalities highlights the need for Sioux City to proactively tackle phosphorus removal instead of waiting for a state mandate to come down.

“We need to prepare the community and the council for these changes and for the cost,” he said.

“We don’t want to have to raise sewer rates to pay for this (phosphorus upgrade).”