Green Guide

Formerly barren part of Truckee River thrives after floods

Posted September 15

— In December, Lori Leonard put finishing touches on a native vegetation project she hoped would repopulate a barren stretch of the Truckee River.

Then she spent the rest of the winter wondering if her work would survive through spring.

Historic levels of rain and snow submerged her work on the Tracy Reach, a portion of the McCarran Ranch Preserve east of Sparks.

Workers had used heavy equipment to haul hundreds of tons of dirt out of the floodplain. The idea was to undo ecological damage from previous channeling projects that had decimated 90 percent of the native plant life and 70 percent of the bird population.

The native seedlings were the final touch. They went in just before the river rose.

"This was essentially bare ground," said Leonard, a restoration technician for The Nature Conservancy.

Then the water rose. And rose. And rose.

At its peak Leonard estimated the river was flowing at about 15,000 cubic feet per second at the ranch, roughly eight times higher than normal, she said.

"We didn't know flooding was going to happen like this," Leonard said.

When it finally receded, Leonard worried she would find the flooding had washed away the river bank and the seeds.

Instead, she found an ecosystem much more vibrant than before, with cottonwood trees, sunflowers, sage and willow pushing out of the ground. The abundant water soaked the soil around the river and gave the seeds a chance to take root.

"We feel very, very excited," Leonard said. "It is functioning well, sort of as we had hoped."

That's important because it means another stretch of the Truckee River could return to what it was like before 20th century development nearly destroyed the area as a living entity.

Back then people thought the best way to control flooding in the Reno-Sparks area was to channelize the river downstream from town, enabling it to carry more water.

They straightened the river and raised and fortified the banks.

One unforeseen consequence, however, was that the water sped up as it traveled through the narrow course and dug deeper into the ground below.

As it dug deeper the water table sank lower and, eventually, it dropped beneath the roots of the vegetation. Trees and plants died and wildlife disappeared.

"It just acted as a drain," Leonard said.

Today, however, the flora is returning which is a good sign for wildlife. Vegetation will help protect the river banks from eroding. And as the cottonwood trees mature they will provide shade that blocks sunlight from reaching the water which will help keep it at temperatures that support fish.

The seedlings survived the flooding in large part because the area Leonard planted is downstream from prior restoration work that re-established a more natural, meandering channel.

Since 2003 the conservancy, along with local, state, federal and tribal governments, restored 10 miles of river at the former Mustang, 102 and McCarran ranches, Lockwood and the Tracy Reach.

By the time water reached the freshly restored area, it had spread out across the flood plain and slowed down, causing less erosion and enabling the latest round of plantings to survive, Leonard said.

"When you have a healthier system, it can take care of itself pretty well," Leonard said.

She said the recovery shows how streams and wetlands, when managed to protect their health, can improve communities around them.

"As the population increases natural space is important," Leonard said. She said The Nature Conservancy is looking to help with forest health projects upstream that could improve water quality in Reno.

"Now we are looking at the headwaters of the Truckee River," she said.

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