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Diving Deeper Shorts: Hydrography

Episode 21 (July 5, 2012)

HOST: During these hot summer days, are you longing to be out on the water? Today on Diving Deeper Shorts, we revisit our interview on hydrography and why this is important for commercial and recreational boaters. We go back to our interview from July 2009 with Jerry Mills from the Office of Coast Survey.

Let's listen in.

HOST: What does hydrographic data tell us?

JERRY MILLS: Kate, the most important thing we can learn from hydrographic data is the depth of the water in a particular area. In order for large commercial ships, military watercraft, and pleasure boats to safely navigate on America's oceans and coasts, mariners need to know where it is safe - or not safe - to steer their vessels.

Hydrographic data collected by my office is used to update NOAA's nautical charts. Nautical charts are like road maps for mariners. Charts are dotted with little numbers, or depth measurements, and symbols which tell a ship captain if an area is too shallow or too dangerous to operate their vessels.

HOST: Jerry, many of our listeners today do not live right along the coast. Why is hydrography important to them?

JERRY MILLS: Hydrography is important to everyone in the U.S. whether you live along the coast or in the middle of the country. Roughly 98 percent of all goods and products that are brought to our country are brought here by ship. This includes petroleum, automobiles, sports equipment, cameras, and many others. In order for ships to safely dock into port, they need to safely travel along our coasts, Great Lakes, canals, bays, and rivers. You can't navigate safely if you don't have a NOAA nautical chart. If ships can't safely dock in port, then people in the middle of the country can't get their products.

HOST: What are the economic benefits associated with hydrographic surveying?

JERRY MILLS: Well, just like our trucks on our highways, captains of commercial ships require hydrographic data on NOAA's nautical charts to safely transit marine highways. More than two billion tons of domestic and international freight travel over our marine highways annually including 3.3 billion barrels of oil to meet U.S. energy demands. Waterborne commerce is a major part of the U.S. economy contributing more than $1 trillion to our gross domestic product.

Also, U.S. ports receive more than 22,000 visits a year from ocean-going container ships. That's a lot of products coming to our store shelves from these ships. Keep in mind, if you live in the middle of the country, these products need to be transported by trucks, trains, or river-bound tugboats and barges from the ocean ports. Operating this marine transportation system requires more than 13 million jobs, another great number for our economy.

That's all for today's show. Want to learn more? Go to and select the July 2009 podcast archive to listen to the full interview on hydrography.

If you have questions on this episode or the National Ocean Service in general, you can contact us at And if you're on social media, don't forget you can find us, its usoceangov, on Facebook, Twitter, Flickr, and YouTube. You can catch our next episode in two weeks.