In the Environmental Report Card poll about the status of ocean life, pollution got more votes than the three other threats — global warming, overfishing, and ship and boat traffic — combined.

Most water pollution comes from activities on land. With each passing year, more people are living in coastal areas of the United States. Increasing human populations bring more opportunities for pollution from land to enter nearby waters.

For instance, each year, more than 28 million gallons of oil from everyday activities, such as driving a car or heating a home, are washed from streets and driveways into our rivers, lakes and streams. That's more than double the amount of oil from Alaska's now-notorious Exxon Valdez oil spill of 1989. Oil-laden water from many rivers and streams winds up in the ocean, where it can foul seabird feathers and smother other forms of sea life.

"We used to think the oceans were so big we could never deplete them," notes the Environmental Defense Network's Oceans Alive campaign. "We now know we were wrong. The challenge for the 21st century is to change our thinking and behavior to maintain the oceans' abundance."

Visit the Save the Planet message board to share your ideas for preventing land-based pollution from ruining our oceans' health.