Tempe Town Lake

Source

March 5, 2007
Town Lake upgrades get Tempe OK
Garin Groff, Tribune

Cleaner water and a new pedestrian bridge are coming to Tempe Town Lake. Swimmers will enjoy the better water in time for this spring’s events, while the bridge will take a couple of years. The city approved work on both projects late last week.

The water improvements will start within the next two weeks, when the city will start diverting millions of gallons of water daily around the lake in a newly built pipeline.

That should stop water on the lake’s east end from spilling over the dam and fouling water quality by boosting algae levels.

The water has pooled at the lake’s east end since a wet spring in 2005. Since then, it’s only been possible to see about one foot into the water. That visibility should increase to about three feet by diverting water from the pond to the east, city officials said.

The increase in algae also boosted pH levels, which sometimes crept beyond federal standards for swimming. That forced the city to cancel one swimming event and change two others.

The city had lowered pH with chemical treatments, but Boyd said the treatments sometimes failed to lower pH levels sufficiently.

By pumping water around the lake, the city should be able to keep pH in well below the limit and ensure swimming events can continue. Basil Boyd, a water resources hydrologist for the lake, said water quality shouldn’t be an issue by the time swimming events start in mid-April.

The city plans to spend about $450,000 this year to rent pumps and buy fuel for the pumping operation. The pumps will divert 15 to 20 million gallons a day. The city doesn’t want to dry up the pond east of the lake, Boyd said, just lower it a few inches below the dam.

The city will only run the pumps about three months in the spring and in the fall, when swimming events are held. There’s no point to pumping water other times because the pH levels are only an issue for swimmers, he said.

The city also has approved a $574,307 contract to design a pedestrian bridge that will cross the lake above its western dam. The city will hold hearings for the public to have a say in the bridge design. The architect, T.Y. Lin International, has an office in Tempe.

The bridge will probably cost about $5.5 million and tie into piers of the western dam. Construction should begin in 2008, said Nancy Ryan, the Rio Salado manager.

The city expects the bridge will be used frequently by people going from the north end of the park to the south.

“We think it’s going to be a great connection,” Ryan said.