MINNEAPOLIS (AP) — A scenic stretch of the St. Croix River was one of 581 waterways Minnesota has added to its list of waters that don’t meet state pollution standards, according to a report released Wednesday.

The Minnesota Pollution Control Agency added the lakes, rivers and streams to its draft list of “impaired waters” that will go to the U.S. Environmental Protection Agency. The 3,416 waterways represent 56% of the state’s waters. The list has been steadily growing over the past decade as researchers evaluate more waterways across the state annually.

The popular stretch of the St. Croix River between Taylors Falls and Stillwater, which forms part of Minnesotan’s border with Wisconsin, made the proposed updated list because of high phosphorous levels. The stretch includes Minnesota’s William O’Brien State Park and rugged bluffs.

“We are very disappointed to see this section of the St. Croix River is proposed to be listed as impaired,î said Deb Ryun, executive director of the St. Croix River Association. “But this potential impairment designation is a reminder that continual work and public action will be necessary to preserve and protect the �- St. Croix we all know and love.”

The St. Croix was one of the first rivers designated under the national Wild and Scenic Rivers program. The 20-mile stretch from Stillwater south to Prescott, Wisconsin, made the impaired list in 2008 due to excess phosphorus.

Most phosphorus, which spurs algae growth, comes from runoff from agricultural or urban areas. Phosphorus levels in the St. Croix actually have been decreasing in recent years due to better controls on wastewater treatment plants and better farming and forestry practices.

Julie Galonska, superintendent of the St. Croix National Scenic Riverway, challenged the idea that the river is deteriorating. She characterized the impairment as an “administrative twist” that resulted from new standards the MPCA recently adopted, not a big increase in pollution.

Miranda Nichols, the MPCA’s impaired-waters list coordinator, said that the newly designated stretch had not previously been evaluated for nutrients and algae under the new standards.

Although the section of the St. Croix north of Stillwater made Minnesotan’s list, it won’t be on Wisconsin’s, Nichols said. Each state sets its own water-quality standards, and Wisconsin has a less stringent phosphorus standard — 90 micrograms per liter compared to Minnesotan’s 40, she said.

Lakes, rivers and streams on Minnesotan’s impaired list have a range of problems, including excess mercury, bacteria, phosphorus, nitrate and other pollutants, as well as struggling fish and insect populations. About one-third of Minnesota’s waterways are considered impaired for recreational use because of high bacteria in streams and phosphorus in lakes.

The public has until Jan. 14 to comment on the draft list. Public meetings are planned around the state in December.

The MPCA plans to submit the list to the EPA by April 1.