Department of Water Resources
A daily compilation of significant news articles and comment
May 8, 2009
4. Water Quality –
Study revealing new facts about the Arroyo
The
By Carissa Marsh
With
In
Kenda Neil, who is studying geological sciences with an emphasis in hydrology, is conducting research along the Arroyo Simi as part of her master's thesis, testing the quality of both ground and surface water to see if the creek could serve as a viable resource for the region's water needs.
The project received funding from the Calleguas Municipal Water District and the Metropolitan Water District (MWD) of
Neil's general study area is the South Las Posas Basin, which includes
Calleguas is currently studying the feasibility of tapping into the basin as an underground water source.
"Calleguas is planning to pump some of the groundwater out of the South Las Posas and potentially keep it for a future groundwater resource," Neil said, adding that Calleguas wants to know the location of the best water to pump.
The Arroyo Simi is a major tributary that drains into the watershed.
Russ Donnelly, education programs manager for MWD, said the district's Southern California World Water Forum College Grant Program provided the financial backing for Neil's research because of the real world usefulness of her data.
"This particular project has a direct and almost immediate application to what Calleguas is doing," Donnelly said.
Due to the drought as well as constrained water resources, the cost of water is set to increase. But utilizing local groundwater resources could offset those price hikes, Donnelly said.
"What you see here is one element of good science," he said of Neil's project. "In order to make a good policy decision, you need good science behind it, and if we can help move that along that's a great outcome for us."
Quicksand in Simi?
Neil first started sampling in July last year, and she'll continue sampling through the summer. She tests for water quality, chemistry, temperature and artesian conditions at six locations along the western portion of the Arroyo Simi.
Somewhat surprisingly, one test location is a quicksand area just west of the
Neil and her graduate adviser M. Ali Tabidian, a professor in the department of geological sciences, stumbled upon the small gray bubbling pool together.
"I've been through this area many times and I've missed it," said Tabidian, who stuck a PVC pipe almost 10 feet long into the quicksand area and still couldn't get to the bottom of it.
Quicksand occurs when high underground pressure causes groundwater to bubble up to the surface, which loosens the sediments and makes the ground soft and unstable.
Tabidian said the 3-foot-wide quicksand area could pose a danger to people walking along the Arroyo if it weren't for the riprap, or man-made rocks, lining the banks of the creek. Still, he said, people should steer clear of the bubbling water because if someone fell in they would sink.
Surface water problems
Another aspect of Neil's research includes analyzing the geochemistry and water quality on either side of the Simi fault to see how the fault influences the route of groundwater traveling between
"It can act like a barrier," said Neil, who works as a hydrologist in the environmental restoration department of the
Tabidian said groundwater in Simi flows west, but rocky, narrow conditions can cause groundwater to back up and seep up to the surface—the reason for the quicksand and the flooding issues on places like
To combat the problem, six dewatering wells on the west end of Simi together pump 2,000 to 3,000 gallons a minute every day. This groundwater is then emptied into the Arroyo.
Another source of drinking water?
One of Neil's sampling sites is a dewatering well on a vacant piece of property on Easy Street.
Neil said the water coming from these types of wells should be treated and used as an alternative water resource, not dumped into the Arroyo.
"There's too much water being discharged into the Arroyo right now," she said.
According to Tabidian, drinking water must have less than 500 milligrams per liter of total dissolved solids (TDS). The water that's discharged into the Arroyo has four times that much.
But if the groundwater were blended with imported water, it would lower the TDS and make it okay to drink, Neil said.
In addition, her research suggests that wells should be built farther from the Arroyo where the TDS levela are lower.
Tabidian said groundwater near the Arroyo and discharge areas has a higher TDS count because more sources impact it.
The data that Neil collects will ultimately be presented to Calleguas, MWD and the county. #
http://www.simivalleyacorn.com/news/2009/0508/community/028.html
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