The most comprehensive assessment so far to date, the report also reveals that agriculture is the main source of 96 percent of nitrate pollution. The five counties in the study area - among the top 10 agricultural producing counties in the United States - include about 40 percent of California's irrigated cropland and more than half of its dairy herds, representing a $13.7 billion slice of the state's economy, Holbrook reports.
"Nearly 10 percent of the 2.6 million people living in the Tulare Lake Basin and Salinas Valley might be drinking nitrate-contaminated water, researchers found. If nothing is done to stem the problem, the report warns, those at risk for health and financial problems may number nearly 80 percent by 2050," writes Holbrook.
High nitrate levels in drinking water have been linked to thyroid cancer, skin rashes, hair loss, birth defects and "blue baby syndrome," a potentially fatal blood disorder in infants.
Holbrook explains that nitrates are odorless, tasteless compounds that form when nitrogen from ammonia and other sources mix with water. While nitrogen and nitrates occur naturally, the advent of synthetic fertilizer has coincided with a dramatic increase in nitrates in drinking water. He notes that rural residents are at greater risk because they depend on private wells, which are often shallower and not monitored to the same degree as public water sources, writing,
"Current contamination likely came from nitrates introduced into the soil decades ago. That means even if nitrates were dramatically reduced today, groundwater would still suffer for decades to come."According to the report, removing nitrates from large groundwater basins is extremely costly and not technically feasible. One relatively low-cost alternative is called "pump and fertilize" pulling nitrate-saturated water out of the ground and applying it to crops at the right time to ensure more complete nitrate uptake.
The report lists a few solutions to help pay for the cleanup of contaminated water, including a fee on fertilizer sales and greater "mill fees" on the production of fertilizer, Holbrook notes, explaining that in California, farmers do not pay sales tax on fertilizer, while water districts and communities bear the cost of cleaning up tainted wells.
The timing of the report is important, notes Holbrook, because the Central Coast water board, one of several regional water agencies that enforce the state's Clean Water Act, will hold a highly anticipated meeting, March 14, to decide on new agricultural regulations aimed at reducing the release of nitrates, pesticides and other chemicals into aquifers, as well as creeks, rivers, lakes and the Pacific Ocean.
You can read the full report here. You can read the previous reporting by the Food & Environment Reporting Network here.