SALT LAKE CITY — At the one-year anniversary of the oil spill that sent 33,000 gallons of crude oil into Red Butte Creek and the Liberty Park pond, known as Liberty Lake, Salt Lake City's mayor is still concerned about the remaining environmental impact of the disaster.

Speaking Friday on KSL Newsradio's "Utah's Morning News," Ralph Becker said cleanup efforts continue on some of the waterways affected by the spill, but other areas have been effectively decontaminated.

"Liberty Lake has been cleaned up well and been completely rebuilt," he said. "We feel good about the condition of the pond."

Becker added that Red Butte Creek "still needs work."

"(Chevron) went through last year and did a series of cleanups by hand up and down the creek," he said. "The challenge is that … you don't want to completely sterilize the creek because then you're killing all the (microbes) that really serve as the foundation for life in the creek."

Becker said cleanup work would continue once the recent flood waters recede, allowing safer access to the affected areas. Chevron said it is still monitoring the creek twice daily.

The leak started about 10 p.m. on June 11 and oil flowed into the creek all night before anyone noticed it. Chevron determined the oil leak came from a hole in a pipeline that was caused by an electrical arc from a nearby power transformer.

About 33,000 gallons of crude oil flowed down into Liberty Lake. Hundreds of birds had to be rescued and treated.

Meanwhile, some local residents in the neighborhood of the spill are expressing worry over potential health concerns. Testing performed by the city's Division of Water Quality showed high levels of carcinogens such as benzo(a)pyrene and benzo(a)nthracene, which can be absorbed through the skin and cause some forms of cancer.

Dr. Brian Moench with Utah Physicians for a Healthy Environment recently sent a letter signed by more than 20 area doctors to Gov. Gary Herbert and Becker, alerting them of the potential health impacts for exposed residents. The group also petitioned for a $2 million fund for a health study.

Becker said the city has filed a claim for its loss of property value from the spill, but is steering clear of sharp criticism for Chevron.

He was also reluctant to give the oil company a letter grade on its response because the work is ongoing.

"Ultimately, it's the end result of the cleanup and the restoration of that creek (that's important), and we're still a long ways away from that being done," he said.