Experiments to test waterway solutions

Long-awaited efforts to improve the looks and quality of water in the Arboretum Waterway are moving ahead in true UC Davis fashion–scientifically.

The pond’s far eastern end—between the A Street Bridge and Aggie Village—has been divided by temporary wooden weirs into sections for a series of experiments in algae control and other improvements to the waterway.

In one section, a pump will move water around. In a second, water will be both circulated by a pump and aerated by a fountain. A third section will be flushed with fresh water pumped from a campus well.

"We’re trying out three different ideas that have been floated over time," said Bob Powell, a chemical engineering and materials science professor who has spearheaded efforts in recent years to improve the waterway.

A campus ad hoc committee chaired by Powell issued a report last November that recommended, among other things, creating water flows through the motionless 1 1/2-mile-long pond by pumping in reclaimed water, ground water or a combination of both.

One of the demonstration projects will measure how well that idea would work.

Like four hoses running full blast

About 21 gallons of water a minute will be pumped from a landscape-irrigation well into one section of the waterway. "That’s about the same as having four garden hoses running full blast," said David Phillips, a Facilities Services engineer overseeing the demonstration projects.

The water will flow to the west and spill over a weir built under the A Street Bridge into the rest of the waterway.

Phillips said the flow of water would be proportionally the same as if all the treated water from the campus’s new wastewater treatment plant were sent through the entire pond.

"That’s our biggest hope for improving the water quality–providing some sort of inflow," Phillips said.

"You want to have it flow out at a rate quicker than algae can grow," he said. "This will replace the water in the section every seven days."

Phillips said the other two demonstration projects will evaluate the effectiveness of suggestions made over the years, but discounted by water-quality experts, to circulate and add oxygen to the water.

"This is going to finally put this to the test and see if there are any benefits to doing it," Phillips said.

The temporary weirs and dams dividing the demonstration projects were built under three bridges for ease of construction and for aesthetic reasons.

They are located under the A Street Bridge, an old bridge that crosses the waterway between Solano Park student-family apartments and Parking Lot 10, and a footbridge to the east.

Signs explaining the projects were expected to go up before the experiments begin this month.

After the first demonstration projects run for about two weeks, a second phase will begin. Water will be pumped at different rates into all sections and the water quality compared.

A third phase of experiments will be based on the results of the previous two. The two most eastern dividers will be removed to create a single section to showcase the most promising methods for improving water quality.

"The proof is in looking at it," Phillips said. "We could do a lot of testing–and we will be doing some of that to measure the physical characteristics of the water–but really what people care about is what it looks like."

Visualizing the possible

"We never expect the water to be Tahoe blue, but this will allow people to visualize what would be possible," he said.

Concerns about algae growth and other water-quality issues in the waterway are about as old as the 31-year-old pond itself.

The waterway, located where Putah Creek flowed before it was diverted more than a century ago, was created for flood control and to enhance the arboretum and campus entrance.

With a number of recent developments–including construction of the Center for the Arts near the arboretum and the opening of a state-of-the-art wastewater treatment plant across Interstate 80–Powell and others saw a new opportunity to act.

Powell, then faculty assistant to Provost and Executive Vice Chancellor Robert Grey, organized an ad hoc committee of campus planners, horticulturists, environmental designers, ecologists, engineers and others interested in improving the pond water.

In its November report, the committee said the waterway–the campus’s main collection basin for storm and irrigation runoff–could become a model of a healthy managed ecosystem. Phillips said the goal is to transform the Arboretum Waterway from a passive stormwater pond into an actively managed campus water resource. The committee also recommended building a series of cascading weirs; creating a wetland to filter nutrients in the water; adding a fishpond to demonstrate the water’s quality; and possibly using water, once it flowed through the waterway, to irrigate landscaping.

Phillips said treated water from the wastewater treatment plant, which is currently discharged into Putah Creek, meets requirements for landscape use. However, he said the campus would first seek public comment as well as approval by the Regional Water Quality Control Board and the state Department of Health Services before redirecting any water back to the arboretum.

"We want to make sure that whatever we do, we don’t adversely impact Putah Creek," he said.

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Amy Agronis, Dateline, (530) 752-1932, abagronis@ucdavis.edu

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