Special Report: Examining the past, to help the future of the Napa River

San Francisco Bay is one of the most ecologically-rich estuary systems in the world. But much of the natural ecology disappeared, after the gold rush.

KTVU meteorologist  Steve Paulson reports how information from the past Is now being used to protect some areas from flooding, during this El Niño winter.

The bay's natural defense against flooding has been altered over the decades. Mudflats and wetlands have been replaced by urban sprawl and farms.

In order to restore the landscape and natural functions of the bay system, experts say we have to look back to see how it was before.

Clues come from trappers' diaries, survey maps, Spanish explorer maps, and even photographs.

Think modern day CSI ecology detectives:
"It's a puzzle...…there are little pieces of info all over the place," said Robin Grossinger, San Francisco Estuary Institute. "Different archives, libraries, historical societies and even peoples personal collections and memories which we have to figure out to how to weave it all together into a coherent picture which take us back 150 to 200 years on how it would have looked, how it functioned and how it would tell us what we can do in the future."

It's an extremely time consuming process developed by the San Francisco Estuary Institute, to take all this information to see how it looked then, and what can be done to improve landscape, and future flood issues.

One area they've focused on is the Napa River Valley.

"Some of the best and earliest maps of the Napa wetlands and river were made by the U.S. Coast Survey and that was in the 1850s, 1858.. just a few years after the gold rush," said Grossinger.

Maps, photos, pollen and even oak trees, which were once very abundant throughout the Napa Valley, are all part of the equation.  Even paintings along the Napa River from 1895 offer clues.

When you start layering in other sources such as aerial photographs, soil maps and exploders accounts, then you really get this rigorous and coherent picture of what the landscape was like," said Erin Buller, historical ecologist.

The Napa River was was straightened and dredged years ago. Yet we can learn from our mistakes.

Steve Paulson reported from the old mill section of downtown Napa, where the Napa River flows in and out, at one time. This was a very bustling area with a lot of industry.  In fact, across the Napa River, one would never know, but about 10 years ago, one area was covered with buildings and a lot of industries, a lumber mill, as well, but that has since all been removed, along with the contaminates have been removed too and the river, which at one time, looked like a canal, looks like it did before.  It's all been restored.

The health of the Napa River continues to improve.

River otters have returned, along with a much healthier fish population and even salmon are returning. This hasn't happened since "probably the early 1900s and possibly the late 1800s," said Shari Gardner, Friends of the Napa River.

"There was a dam on the Napa River that probably kept salmon from spawning in the river for about 30 years, so the chinook salmon are moving back into the river and really exciting to see."

If, and when El Niño rains do return, the restored river, marshlands and mudflats will allow water to flow more naturally, and not overwhelm the city of Napa.

"We've learned a lot from historical ecology about how to design natural flood protection so that we're working more in sync with the river instead of fighting it all the time," said Grossinger.