Santa Ynez River Valley communities’ water contaminated, study says
Groundwater in some areas of the Santa Ynez River Valley is polluted, and a recent study suggests that septic tanks may be contributing to the contamination.
The study, which was overseen by the Central Coast Regional Water Quality Control Board, found that all the subbasins in the area — including Lompoc, Santa Rita, and Santa Ynez — had wells with pollutant levels higher than benchmarks established for safe drinking water.
That discharging effluent from a septic tank into the ground affects groundwater may be obvious for some. Determining the effect of septic tanks on groundwater quality, however, is complicated by the fact that other factors — agricultural activity and rain — also play a role in the quality. To get around this complication, the research analysts built a statistical model to see how significant septic tanks density was for nitrate concentration.
The reason nitrate was chosen as a pollution indicator was not random. Drinking water with high levels of nitrate is harmful, especially for babies.
“Excessive nitrate can result in restriction of oxygen transport in the bloodstream,” according to the United States Geological Survey. “Infants under the age of four months lack the enzyme necessary to correct this condition,” which is known colloquially as the “blue baby syndrome.”
A commonly accepted benchmark for safe drinking water is 10 milligrams per liter, and some areas surveyed in the study had water levels that surpassed the benchmark by more than five times.
The statistical model was conducted for the entire Santa Ynez River Valley groundwater basin and also for just the Santa Ynez subbasin. While the results for the entire groundwater basin was not statistically significant, results for the Santa Ynez subbasin were highly significant, with p-values of less than 0.01.
The statistical equations predict that in areas where there are 425 septic tanks per one square mile — such as near the Janin Acres subdivision or the town of Santa Ynez — one septic tank will increase the groundwater nitrate concentration by about 5 to 7.5 mg/L.
Rick Merrifield, the former Santa Barbara County Environmental Health Services Director, told the News-Press that septic tanks “are not bad things, but the problem is that some of them are built in places that aren’t really appropriate.”
What makes a place inappropriate for a septic tank? A small area of land. Mr. Merrifield said that there should be a septic tank should be in a lot that is at least 1 acre.
“The problem with Los Olivos is that those lots were created in the 1980s, and most of them are very small,” said Mr. Merrifield. “They’re nowhere near as large as they should be.”
Mr. Merrifield also added that “many of the [septic] systems in the Santa Ynez Valley are getting old” and need to be moved to different disposal sites.
“Everyone who builds a septic system gets a permit, and everyone’s supposed to identify the areas within their lot they can dispose effluent at,” said Mr. Merrifield. “But not everyone’s doing that.”
In Santa Barbara County, “septic systems newly installed or repaired have stricter requirements for protection of water quality,” according to Thea Tryon, an engineering geologist with the Central Coast Regional Water Quality Control Board.
When asked about prohibition in areas where water quality is extremely contaminated, Ms. Tryon said, “We need evidence of direct discharges from the septic systems that cause significant impacts to water quality before we begin working towards prohibiting discharges which would lead to sewering.”
Sewering projects, however, may upset community members that like to live in a rural area, according to Mr. Merrifield.
“They like controlling their own property, their own destiny,” he said.
The transition from septic system to sewage system, however, is inevitable, Mr. Merrified said.
“The longer you wait,” he said, “the higher the cost goes up.”
The community’s residents are typically responsible for the cost of building and connecting to a sewage system, according to Ms. Tryon, who added that there are “potential offsets from grants, low interest loans, or businesses that can’t meet septic design criteria and want to expand or build.”
Until such projects are undertaken, however, communities in the Santa Ynez River Valley are left with contaminated water. The research findings suggest that “domestic well users may be at risk of drinking water above the drinking water standard. The areas at the highest risks are near the towns of Los Olivos, Santa Ynez and Janin Acres, according to the study.
In the Lompoc Plain Subbasin, the highest levels of pollutants found are as followed. Level of arsenic was more than four times the benchmark; iron, almost 250 times; nitrate, more than 10 times; sulfate, more than eight times; and total dissolved solids, almost 25 times.
In the Lompoc Terrace Subbasin, level of arsenic was more than 250 times; iron, more than 1,000 times; nitrate, more than eight times; sulfate, more than 10 times; and TDS, more than 150 times.
The Lompoc Upland Subbasin was the only region where the maximum nitrate level was lower than the benchmark. Arsenic was five times higher than the benchmark; iron, almost 15 times; sulfate, more than three times; and TDS, almost four times.
In the Santa Rita Subbasin, arsenic was more than five times higher than the benchmark; iron, almost 90 times; nitrate, almost three times; sulfate, almost five times; and TDS, more than five times.
In the Santa Ynez Subbasin, nitrate was almost four percent higher than the benchmark while arsenic was three times higher than the benchmark; iron, more than 100 times; sulfate, more than five times; and TDS, more than three times.
The study, whose data was compiled and digitized by Cal Poly San Luis Obispo graduate Riley Haas, was funded by the nonprofit Heal the Ocean, whose advisory board includes Mr. Merrifield. Howard Kolb and James Bishop of the Central Coast Regional Water Quality Control Board also worked on the report, titled “Santa Barbara County Groundwater Characterization Project: Santa Ynez River Valley Groundwater Basin.”
