A rendering shows the weirs coming to the waterway.

Arboretum Waterway Improvement Begins

by | May 30, 2017 | Environment, On Campus, Spring/Summer 2017

First it flowed east. Then it hardly flowed at all. Soon it will flow gently to the west — making the campus waterway a more dynamic element of the UC Davis Arboretum.

Construction underway now and through the summer will transform the east end of the arboretum waterway from a stagnant pond into a calm cascade over five weirs leading to Lake Spafford.

This is phase one of the Arboretum Waterway Maintenance and Enhancement Project, which, among other things, is meant to keep the waterway from becoming stagnant and overridden by algae and weeds. Subsequent phases over the next four years call for similar improvements from Lake Spafford to Putah Creek Lodge. Then, from the lodge to the west end of the waterway, plans call for an emergent marsh, open water and riparian forest habitat, for the benefit of wildlife and visitors by way of a new boardwalk and viewing platforms.

First, Valentine Corp. of San Rafael is dredging and regrading the channel in the east end — building a 15-inch drop in elevation that will at long last give the waterway the flow it deserves, to be achieved by recirculating water from below the last weir and back to the east end.

Duckweed and algae thrived on the water before a cleanup last year.

The gabions (retaining walls made of rocks encased by chicken wire) along the waterway will be disassembled, and the banks recontoured into gentler slopes to the water. Alongside the waterway, the paths will be improved to bring them up to modern accessibility standards.

The dredging is part of normal maintenance (and overdue, not having been done for 20 years). The flow is new — and desperately needed. Last summer the arboretum brought in a company to sweep out the green yuck.

The lack of flow owes to the fact the waterway is not a creek. It’s a remnant of a creek, the North Fork of Putah Creek, which flowed east and frequently flooded Davis — prompting the citizenry to divert the water to the South Fork of Putah Creek. The university eventually turned the old channel into the waterway that you see today — dammed at both ends. It collects storm runoff, and, at a certain level, the water drains over a weir at the west end and is pumped to the south fork.

“This enhancement project gives us the best of both worlds,” said Bob Segar, assistant vice chancellor for Campus Planning and Environmental Stewardship, “a state-of-the-art water management system, and a more natural waterway that adds to the arboretum’s beauty.”