SAGLE - The answers aren't getting any easier for the beleaguered Southside Water & Sewer District.

The district's plan to dissolve a four-year-old moratorium on new hookups to its system by discharging treated wastewater into the Pend Oreille River has been thrown for a loop because the Idaho Department of Environmental Quality recently listed the river as impaired for excessive phosphate.

Elevated levels of phosphate can generate excessive algae growth, which depletes dissolved oxygen in a body of water.

The impairment designation, which applies to the stretch of river between Sandpoint and Oldtown, could prohibit Southside from adding to the nutrient loading.

"Right now, we're in limbo," Southside Chairman Gary Wescott said on Wednesday during a teleconference with the Pend Oreille Basin Commission.

The district was seeking state and federal approval to enhance its treatment capacity with a membrane bioreactor, or MBR system, which would have allowed the stringently treated wastewater to be discharged into the river.

Now the district is looking into discharging into the Sagle aquifer.

"In the interim, we are investigating the possibility of using the MBR system and a groundwater regeneration or recharge system. It has a lot of questions to it and I don't know where we're going to go with it," Wescott told commissioners.

The nutrient-impairment listing could pose problems for other dischargers, such as the cities of Sandpoint and Dover, municipalities which will eventually have to renew their discharge permits, Wescott added.

Tom Herron, a regional water quality manager for DEQ in Coeur d'Alene, said the listing should not have come as a surprise because it has been a topic of discussion at Watershed Advisory Group meetings attended by dischargers.

"What we're doing is looking at water quality conditions to determine what kind of permit limits are going to be supportive of water quality in the Pend Oreille River above the Albeni Falls Dam, particularly because that's the most sensitive reach with the most at stake," Herron said during the teleconference.

Herron said the department is working on developing an interim threshold target. The DEQ's technical services bureau is conducting a loading analysis to determine the ambient level of phosphorus and how much more, if any, could be discharged into the river without degrading water quality.

"As we see what we would call the assimilative capacity increasingly taken up by development on the Pend Oreille River, that pie is shrinking and the manifestation of water quality issues is increasing," Herron said.

Preliminary results of the data-gathering effort are slated for discussion during a meeting hosted by DEQ on Wednesday, Dec. 10, at Sandpoint City Hall. The meeting lasts from 1-5 p.m.

A more comprehensive Total Maximum Daily Load threshold for the river is slated to be developed in 2013.