A new county ordinance is now in effect that requires those floating on rivers in unincorporated areas wear a life vest, just as warm weather should draw plenty of folks to rivers and lakes over the July 4 weekend.

The high on Saturday could reach near 80 degrees in Renton, with Sunday somewhat cooler. Sunny skies are forecast for the Monday holiday, with highs in the mid-70s.

The county’s new rule applies to major rivers, including the Cedar before it flows into Renton. The City of Renton doesn’t have a similar regulation requiring personal flotation devices, but it encourages their use.

“We always have concerns about people being smart around the rivers,” said Terry Higashiyama, administrator of the Renton’s Community Services Department, which includes parks and recreation areas in the city.

The lower stretches of the Cedar don’t have the snags and other large wood that’s more common upriver, she said. Nor are their deep holes. “Our flow through Renton is pretty straightforward,” she said.

Still, she encourages parents to have life jackets on their children when near the water. “Things can happen in inches of water,” she said.

She suggests taking a dip in one of Renton’s two swimming beaches on Lake Washington that have lifeguards.

Lifeguards are on duty at Gene Coulon Memorial Beach Park and Kennydale Beach Park daily noon to 8 p.m. through Labor Day, Sept. 5. Henry Moses Aquatics Center also has lifeguards; its open swim hours are noon to 3:30 p.m. and again from 4:00 p.m. to 7:30 p.m. The pool is also open through Labor Day.

For much of the late spring, officials have warned that rivers are running particularly high and cold for this time of year. Conditions may have improved, according to officials, but log jams can trap swimmers and large rocks or logs can tip over rafts, canoes and kayaks.

“With melting snowpack at much higher levels than normal, our rivers are fast moving and the risks for drowning are much higher,” says Mark Peterson, Fire Chief /Emergency Services administrator. “Drowning can be easily prevented by wearing a life jacket, keeping a close eye on children when they are in or near the water, and learning how to perform cardio-pulmonary resuscitation (CPR).”

State law says all children 12 and under must wear a Coast Guard approved life jacket or vest on all vessels 19 feet and under.

The county’s new rule is in effect through Oct. 1. It excludes fishermen or those wading within five feet from shore or in water less than four feet deep.