EDINA, Minn. -- Many pools across the state aren't even open yet, but already two Minnesota kids this season have drowned.

That's why pools are sending an urgent reminder to parents and caregivers to closely watch children near water.

The Edina pool is among many opening this weekend, and says its 45 lifeguards go through nearly a week of intense training, a mentoring program and workshops every two weeks.

But with as many as 3,000 people using the pool on a weekend day, and as many as 800 in the water at one time, lifeguards say they can't watch everyone.

"We should be a last line of defense," said Bill Moir of the Edina pool.

Moir says he encourages parents to enroll their children in swimming lessons, and that many pools, including Edina, offer life jackets free of charge.

But he said those precautions are no substitute for following safety rules and good supervision.