PROVO — The soupy green swirls of blue-green algae on the surface of Utah Lake aren't pretty — but worse, they could be deadly.

Utah Lake's high phosphorus levels have created a breeding ground for the algae, which can create massive, slimy blooms in the right conditions. If too much of the algae grows, then dies, the results could be catastrophic for the lake's ecosystem, according to a report released Wednesday by Utah's Division of Water Quality.

"Where conditions are right, the algae take off, and then they die off, and you can have a dissolved oxygen crash and the fish go belly-up," Utah Division of Water Quality environmental scientist David Wham says. "When you look at the dynamics in Utah Lake and the species (of algae) we're dealing with, it really is a cause for concern because these kind of impairments have caused problems in other bodies of water that are similar to Utah Lake."

Blue-green algae is an indicator of unhealthy water, Wham says, which is one reason why Utah Lake has been on Utah's "impaired body of water" list for years. The lake is listed as being impaired for two issues: high levels of phosphorus and high levels of salinity.

It's the Division of Water Quality's job to figure out how to decrease those levels — and ultimately get Utah Lake off the impaired list — but Wham says the task is easier said than done. The high levels of salinity are naturally occurring, and as for the phosphorus, finding a limit to how many nutrients can be in the water is a difficult number to pinpoint.

The division's recent study shows that the lake has high phosphorus levels and that 76 percent of the lake's phosphorus comes from surrounding waste water treatment facilities, but a direct connection between the phosphorus and the health of the lake's fish hasn't been found.

The division is also missing some data from their report — a determination of how much phosphorus in the water is too much — but a fear that the tipping point could be frighteningly near has prompted the division to make a recommendation that may cause some criticism.

"It's not a healthy ecosystem, I think we can all agree to that," Wham said Wednesday to a room full of Utah Lake stakeholders, including representatives from several cities that border the lake. "We do have some holes in our data set, and it's enough to give us pause, given the other symptoms of the lake, but we're not comfortable washing our hands of it and walking away and saying it looks fine."

The Division of Water Quality is advocating that the best way to reduce the lake's phosphorus will be to require the waste treatment facilities to remove phosphorus from their effluent flow through a biological phosphorus removal process.