With rapid development in the southwest area of Salt Lake County along with pressure to build a new sewage plant, the time has come for a comprehensive, end-to-end look at the Jordan River's water quality.

So says the state's top water quality administrator.

The Jordan River is "above the standard — barely" of dissolved solids, oxygen and other indicators of pollution, Don Ostler, director of the state Division of Water Quality, told the Salt Lake County Council of Governments on Thursday.

While studies of limited stretches of the river have been done in the interim, the last study of river quality as a whole was done in 1978 — 26 years ago. "It's just old," Ostler said. "We don't know what is valid any more."

Burgeoning development that is stressing the river like never before is also increasing the need for a fifth sewage treatment plant in Salt Lake County, the construction of which would obviously stress the river even more.

As currently envisioned, the plant would be the county's third to discharge treated effluent into the Jordan River. (The Central Valley and South Valley sewage treatment plants already discharge into the river, while Salt Lake's treatment plant discharges into a canal and Magna's into a smaller river.)

Effluent from all of the plants eventually reaches the Great Salt Lake.

A proposal for a new sewage treatment plant in South Jordan, next to the Jordan River, was withdrawn last January because of citizen complaints. But the reprieve was only temporary. South Jordan Sewer District general manager Craig White said the district's West Jordan plant, equipped to treat 13 million gallons a day, is now treating 12 million gallons a day with more looming on the horizon, making the need for an additional plant increasingly acute.

"It is a thorny issue" in terms of water quality, Ostler said. "It is one we will have to grapple with."

Utah County officials are just now gearing up to do a water quality study on Utah Lake, which makes a similar study on the Jordan River — running from Utah Lake to the Great Salt Lake — particularly timely. The two studies could also be coordinated for better overall results.

"Twenty years from now people are going to be saying, 'Why didn't they do something?' " if no study is done, said West Valley Mayor Dennis Nordfelt.

The most pressing issues of Jordan River water quality have to do with its levels of salinity, ammonia and dissolved oxygen. Partly because of Utah's ongoing drought, Utah Lake is becoming increasingly salty, which transfers to the Jordan River.