AUSTIN (KXAN) — Austin city officials say pet owners still shouldn’t let their dogs swim in Ladybird Lake or the Red Bud Isle area.

MORE: No relief in sight yet from toxic algae bloom

The latest water samples in those areas still tested positive for the neurotoxins that first raised alarms in early August.

The city’s Watershed Protection Department took more samples on Monday. Those results should be in by early next week.

City of Austin Environmental Scientist Senior Brent Bellinger says too much rain last fall and winter contributed by washing in nutrients that algae feed on. He says zebra mussels could also be to blame. Those factors, mixed with hot weather can grow algael blooms.

Now, Bellinger says, the hope is that cold water will kill the blooms.

“What we’re really hoping for with the water is to consistently be below 75 degrees,” Bellinger said. “It really needs to be persistent, you know. Just a couple of days of cool weather really isn’t enough.”​​

Bellinger says smaller rain showers could be problematic, washing in things like fertilizers or animal waste that feeds the algae.​

However, a lot of rain could help wash out the blooms.

“When you get kind of persistent rain, continuous rain, then your water quality improves with those flushing events,” Bellinger said.

This year, it’s a waiting game to see when the algae will move out.​ Meanwhile, city scientists are already looking toward 2020, studying this summer’s blooms, and preparing for the potential of more next summer.​​​

“As we get more data, we’ll look at, well, what are some of the mitigation options in the future instead of just sitting back and waiting. Is there a way we can be more proactive, or ideally just prevent this from happening?” Bellinger said.

