Putah Creek flows due east from Lake Berryessa, passing through the cities of Winters and Davis, CA, on its way to the Sacramento River before finally draining into the San Francisco Bay Delta.

Some 300,000 people in Solano County get their drinking water from Lake Berryessa Reservoir and tributaries below the reservoir that flow to Putah Creek. Seven miles below Monticello Dam (at Lake Berryessa) lies Putah Diversion Dam, which forms Lake Solano and diverts flow from Putah Creek into Putah South Canal.

The dams and canal are the main features of the Solano Project, which delivers raw drinking water for municipal and industrial use. The Solano Project also provides surface water to irrigate over 70,000 acres of farmland.

This chain of lakes, reservoirs, creeks, and tributaries is an essential component of life for residents in the area. Water not only is needed for residents but is essential for farms and livestock to flourish. Without this water supply this area could not function properly.

In 1987 Putah Creek, Lake Berryessa, and the surrounding area began a record seven-year drought. Normal rainfall finally returned in 1994, and the near-empty reservoir filled in just three years. For the local residents, this was a glimpse of how important their water supply was.

Putah Creek forms the northern boundary of Solano County and the southern boundary of Yolo County for much of its length. For Solano County, the creek is an essential water source. For Yolo County, it is an environmental amenity.

Between 1994 and 2004, the two affected counties tried to reach an agreement on how to protect their water supply for human and environmental benefit. With environmental interests and water interests competing for scarce water, reaching an agreement was difficult. When the settlement was finally reached, the agreement between the two counties was to guarantee permanent flows in Putah Creek, making it a perennial stream. A perennial stream would guarantee the flow of water to all areas and would maintain the levels of Lake Berryessa Reservoir.

Once the two counties finally reached the decision, a new problem presented itself. While the litigation was taking place, invasive vegetation had grown in force along the banks and within the channel of Putah Creek.

The problem with invasive vegetation growing in the creek channels is that it contributes “roughness,” slowing the flow of water and therefore the flood-carrying capacity of the channel.

The effect of vegetation on the flow of water can be observed long after floods as an accumulation of sediment around plants. When flow velocity drops in the vicinity of this vegetation, the sediment-carrying capacity is reduced and sediment settles out. This further impedes the flow of the stream.

One of the goals of the Putah Creek stream keeper is to replace invasive weeds that impede flows with native grasses and tall trees that enhance flow capacity and resist reinvasion by weeds. In addition, since the weeds are foreign to the creek they provide little or no habitat value to native fish and wildlife.

While the process of clearing and replacing these invasive weeds was not going to be easy, the Putah Creek stream keeper was in charge of making it happen.

“At the start of the project we used backpack sprayers and ATV-mounted sprayers to control the arundo and tamarisk that grow as individual clumps,” says Marovich. “Tackling the Himalayan blackberry was a different story.”

Himalayan blackberry, an evergreen shrub, can grow up to 3 meters tall. It is a tangle of stems that are covered in thorns, a more effective barrier than concertina wire. It sends out runners to start new plants and has extensive regeneration capabilities. This presented a problem for Marovich and his team. They needed to find the right equipment to remove the invasive vegetation but also be environmentally sound.

“It was clear from the beginning that a four-wheel tractor would never make it through the blackberry patches, and it was just too difficult for someone to physically maneuver past the thorns and stems,” explains Marovich. “We tried a 40-horsepower four-wheel-drive tractor, but the terrain was too rough for the machine to handle. Bulldozers can create access routes, but they drastically alter the landscape, often in ways that destroy a certain amount of habitat and increase the risk of soil erosion.”

Marovich and his crew needed a way to travel through this rough and changing landscape with minimal disturbance. They chose an ASV rubber track loader for several reasons. With its enclosed cab, they were able to push their way through the thickets of blackberries. The rubber tracks and the limited ground disturbance allowed them to push or lift unseen logs and maneuver up and down ravines where traditional tractors could not operate.

The ASV RC-100 has an operating weight of 10,150 pounds but only 3.5 pounds per square inch ground pressure. This was the upper hand Marovich was looking for. “The ASV, especially with the root grapple and the timber ax attachments, allowed us to access areas such as those covered by dense blackberry thicket that were formerly inaccessible,” he says. “We have been able to take on our most challenging sites and blaze trails into areas of properties that landowners have never seen.”

As far as the invasive vegetation, Marovich and his crew can get 90% or better control of the weeds in any given year. Getting there took time and lots of energy.

“The berries were so entangled with the cottonwoods, willow, and wild grape that I had all but given up hope of ever controlling them,” recalls Marovich. “In our climate, Himalayan blackberries do not go completely dormant. To control them, we use glyphosate herbicide [Aquamaster] in the winter months to selectively control the blackberries and not harm the native vegetation. Once we blazed trails through the blackberries and the storm debris, we were able to follow with an ATV-mounted sprayer.”

The result was 16 acres of berry control and no damage at all to the dense forest of native trees and vines. This is a long-term project involving 2,000 acres of riparian corridor. Marovich and his crew are still tackling the invasive vegetation, and they continue to win the battle.

Finding the right equipment is essential for any project. For Marovich, the ASV proved to be an indispensable resource for maintaining the watershed and getting the most environmental benefit for the area.

There were many benefits from this project. The weed control improved drainage in high-flow events, but the most far-reaching aspect of the project was the environmental benefits for fish and wildlife habitat. This project created a naturally functioning ecosystem, free from the impacts of foreign and invasive plants.