The City of Sonoma, the Sonoma County Water Agency and the Sonoma Ecology Center are collaborating on a series of integrated projects to better manage Valley water, with the most recent work creating a highly visible presence at Montini Open Space Preserve.
The project, in which geologists and hydrologists are currently taking ground samples and drilling test wells in the Fifth Street West meadow at the edge of the preserve, is part of the larger City Watersheds of Sonoma Valley Project. That effort is a multi-benefit project being developed to help address local flooding, promote groundwater recharge and enhance habitat along Fryer Creek. The water agency and its partners recently received a $1.89 million grant from the Department of Water Resources in a statewide competition for its $4.14 million project.
Betty Andrews, who is a principal engineer focusing on environmental hydrology at Environmental Science Associates, Phillip Williams and Associates (ESA PWA),
is working to actively implement the watersheds project in Sonoma through site investigations and research with her team.
The project’s first priority, Andrews explained, is reducing flood hazards by finding the best locations for reduction. In addition to looking at Fryer Creek and areas within the city, researchers are paying specific attention to Nathanson Creek because, if that creek floods, it has the potential to affect the most people in the surrounding city neighborhoods.
The project proposes flood reduction along the main stem of Fryer Creek by capturing runoff and diverting storm water as part of an effort to enhance wetland areas at Montini.
The second objective, she noted, is finding an area of focus with the best potential for groundwater recharge to increase the reliability of the area’s water supply.
Water agency hydrogeologist Marcus Trotta explains one facet of the project at Montini examines the property’s potential for retaining water by contouring the land, building detention basins to slow the flow and capture water, thus allowing water to better percolate into the ground.
“There are opportunities for mixed benefits for this project,” Andrews said.
The project is currently in its first phase, with site investigations and studies taking place so engineers and scientists can collect samples to identify areas most suitable for storm water recharge and water retention.
Other aspects of the project include modification and replacement of a culvert on Fryer Creek at West MacArthur Street because it is currently a “flow trap,” as loose sediment and debris make it difficult for local fish to pass through, and it limits water flow. Another aspect of the project is vegetation management at Fryer Creek, removing excess sediment and invasive weeds, while reshaping the channel banks and replanting native plants.
Hydrologist Jenny Cherney, from Daniel B. Stephens and Associates, a national team of scientists, has been working on site to investigate soil conditions. Cherney and her team are taking samples of the soil at Montini Preserve, using a drill rig, and are installing monitoring wells. This allows the team to check groundwater levels and determine how the soil absorbs water. “We are collecting soil samples to test them for properties that would be most compatible with projects related to recharge,” she said.