In July 1938, Dr. Arthur Lien, Spokane’s health officer, issued this warning about the Spokane River: “Persons who insist on swimming in the river are subject to arrest.” Raw sewage was dumped into the river back then and Lien worried about swimmers contracting typhoid. He also wanted to cut down on the “numerous drownings charged against the river.”

Now it is summer 2006 and the warnings from 68 years ago are relevant still. More than 300 people have drowned in the river since 1938. One of the most dangerous times on the river occurs in early summer, when the weather can heat up dramatically, as it has in recent days, making the river’s cooling waters very appealing.

The 111-mile Spokane River can be deceiving. It looks as calm as a lake in many places, and sometimes the calm on the surface reflects the reality beneath. But in many places, strong currents race below that surface. Swimmers wade in unaware, get caught in the current, panic, flail and drown. Last Sunday, a 22-year-old man got caught in a current at Plantes Ferry and disappeared.

The typhoid scare of 1938 disappeared when treatment plants were built along the river, transforming raw sewage into treated wastewater. But the river still contains toxic chemicals. State ecology officials announced recently that the Spokane River contains more of the fire retardant chemical PBDE than any other waterway in the state.

The river has been under a fish consumption advisory since 2003, because of elevated levels of another toxic chemical, PCB. Fish caught between Idaho and Upriver Dam should not be eaten.

The Spokane River’s story first intersected with humans when regional tribes discovered its salmon runs — now gone — and claimed the river as a place for gathering and bartering. It has always been both a source of life and livelihood and a place where death can arrive swiftly.

The river is more popular than ever. The cost of homes built along the river, especially in its Post Falls stretch, has skyrocketed. The proposed whitewater park beneath Sandifur Memorial Bridge has beckoned more people to river’s edge. The Centennial Trail’s popularity with walkers, joggers and bikers grows each season.

The river will always be true to its nature, no matter how popular it becomes, so it’s up to the users to respect its power and force.

The respect begins with wearing a life preserver when on the river, especially when swimming. It means that kayakers, rafters and other boaters should not overestimate their skills in navigating this river.

And river respect means, in some instances, that you don’t swim in it at all. In 1938, health officer Lien recommended swimmers choose pools and lakes over the river. His advice may be timely again, especially along stretches with strong currents.

The phrase “be careful out there” has become a cliché, but clichés often contain a deeper truth. The Spokane River claims victims almost every summer season. Taking care out there is the first line of defense against becoming the next one.