Why California’s Nitrate Problem Will Take Decades to Fix

The state has a long-term plan to clean up nitrate-contaminated groundwater, but farmers say more research is still needed and environmental groups think the proposal isn’t strong enough.

Written by Erica Gies
Published on Aug. 31, 2017

Dairy lagoon
On most California dairies, liquids and fine particles from cow manure end up as nutrient-rich wastewater in lagoons like the one pictured. An alliance of industry, conservation and academic partners is testing and scaling an innovative system to utilize this liquid manure in underground drip-irrigation lines to grow crops at a handful of San Joaquin Valley dairies. Paolo Vescia

When folks talk about “black gold” in California’s Central Valley, it’s usually a reference to oil – unless you’re in the dairy business. No state in the country produces more milk than California, thanks to its 1.7 million cows. Those cows also produce a lot of manure – 120 pounds per cow per day. But manure isn’t a problem; it’s an opportunity, says Ryan Flaherty, director of business partnerships at the San Francisco-based Sustainable Conservation, a nonprofit that works with diverse stakeholders to help clean water, air and land.

Many farmers use this waste as a resource, spreading the manure on fields that will be used to grow crops to feed the animals – a virtuous circle of sorts.

There’s just one problem: crops don’t absorb all the nitrogen in the manure, and the excess runs off into surface water, where it can cause algae blooms, or percolates down into aquifers as nitrates. Sustainable Conservation is working with dairy farmers to fix this issue, but it’s one component of a bigger problem.

It’s not just nitrogen from dairy waste that contaminates groundwater. Nitrogen-rich fertilizer applied to hundreds of crops has helped make California’s agriculture industry a powerhouse, producing one-third of the vegetables and two-thirds of fruits and nuts in the United States. But that has come at a cost.

Nitrate-contaminated groundwater is now pervasive in agricultural areas in California such as the San Joaquin and Salinas valleys. It’s a serious problem in rural communities that rely solely on wells for drinking water because it can cause health problems or even death, especially for infants and pregnant women.

In the two most affected regions in California, Tulare Lake Basin in the San Joaquin Valley and the Salinas Valley, most nitrate pollution comes from crop runoff – 55 percent from synthetic fertilizer and 33 percent from animal manure – according to a University of California, Davis study commissioned by the State Water Resources Control Board. Other sources, such as animal waste from dairy and meat production and overwhelmed sewage and septic systems, can be locally important.

Based on that study and other input, the state came up with a long-term plan to address nitrate pollution, but not everyone is happy with it. Many farmers find parts of it burdensome, and some environmental groups say that the plan lacks teeth and that regulators aren’t doing enough to enforce clean water laws.

Coalition Building

The first step for the state in attacking its nitrate problem began with getting the right people to the table.

A coalition of state and federal agencies, growers and environmental justice groups, known as the Central Valley Salinity Alternatives for Long-term Sustainability (CV-SALTS), developed a plan to sustainably manage salinity and nitrogen in the Central Valley.

CV-SALTS laid out a three-tiered approach to nitrate pollution in the Central Valley: first, provide safe drinking water to affected communities; then stabilize the amount of nitrates in groundwater; and finally clean up groundwater.

The last is particularly challenging. Cleaning up the groundwater can be done through various processes, such as reverse osmosis or ion exchange, but they tend to be time-consuming and expensive, and some are only able to process low volumes of water. For that reason, restoring groundwater is likely not going to happen in any concerted way, says Daniel Cozad, executive director of the Central Valley Salinity Coalition, a group that raised funds for CV-SALTS’s scientific studies.

Jeanne Chilcott, environmental program manager for the Central Valley Regional Water Quality Control Board, agreed. “Even with the most aggressive pumping, treating and reinjecting clean water back in groundwater system, it would be 50 to 70 years before you see an improvement in water quality,” she says. Cleaning technologies would also generate a significant and costly waste stream.

“We don’t want to give up on our groundwater basin,” Chilcott says. “But to think the solution is to first clean up groundwater basins is not borne out by studies.” Instead the state needs to “prioritize resources to make sure people have a safe supply in the meantime,” she says.

Controlling Source Pollution

The next step is not making the problem worse. In areas with nitrate problems, growers are now required to create reports, called nitrogen management plans, that record how much nitrogen they apply and when, and whether it’s commercial, synthetic or organic, says Sue McConnell, Irrigated Lands Regulatory Program manager with the Central Valley water board.

They also report on their crop yields. Because there are estimates for how much nitrogen each type of crop will consume as it grows, they can calculate the difference between the two to get a general idea of how much nitrogen is left over in the soil, where it can leach into groundwater.

Many farmers are part of grower coalitions, which look at the reports to find members who are applying much more nitrogen than their neighbors, says McConnell.

So far that’s been a merely educational exercise, in which the outlier is notified “and encouraged to reduce,” noted Chilcott.

Nitrogen management plans must be kept on site, but growers are not required to submit them. “If inspectors come to site, they can ask to see it,” McConnell says. “Last year we visited 114 growers out of 30,000. We have 18 staff, so we have limited ability to touch them individually.”

The reporting regulations can also be burdensome for some growers. Parry Klassen grows peaches on a small farm near Kings River and manages the East San Joaquin Growers Coalition, where he works with large farming operations. He says that although the nitrogen management plans are not a huge burden for him, he sees that they can be a challenge for others. “If you have thousands and thousands of acres, it is time-consuming,” Klassen says. “A lot of these farms have a person who is committed to doing just this for several months of the year.”

New Ideas

Farm worker Honorio Nunez stands near boxes of bottled water, the only water he and his family have to drink because their domestic well is tainted with dangerously high levels of nitrates, in East Porterville, California. (AFP/ROBYN BECK)

A possible win-win that could come out of nitrogen measuring and reporting is a technique called pump and fertilize. Farmers in some areas tap groundwater to irrigate their fields. If they measure the amount of nitrates in the groundwater they use, they can reduce the amount of new nitrogen fertilizer they apply to their crops, says Covad.

“We’ve been pushing that a lot,” says Klassen. “I’ve had conversations with tons of growers who say, ‘I never thought of that before.’ Some farmers don’t even fertilize anymore in the high nitrate areas.” In those cases, pump and fertilize is the most efficient, cost-effective way to clean up groundwater because the crops are removing some of the nitrogen from the water, and farmers aren’t adding extra.

Sustainable Conservation has been working on another possible solution to help dairy farmers reduce their contributions to nitrate pollution. That is especially a concern in counties like Tulare, which leads in milk production and also grows a lot of feed crops.

Many dairy farmers “fertigate” – they mix their manure-based fertilizer with water and flood-irrigate their fields. But it’s not the most efficient use of water, or the most precise way to get nutrients to crops, and it worsens nitrate pollution. So Sustainable Conservation has spent the last few years piloting a technology that allows water mixed with manure to be put through drip irrigation without clogging the drip tape – something that kept most dairy farmers from using drip irrigation in the past. Drip irrigation is generally a more precise way to get irrigation water to the roots of the plant, where it can take it up, thereby reducing runoff that can carry pollutants with it.

So far the results have shown what they’ve hoped for, says Sustainable Conservation’s Flaherty – an increase in crop yields because the nutrients are evenly distributed at the root zone and a reduction in water and nutrient use. The project has received more funding to expand to three dairies.

Research Drives Action

A custom system engineered by project partner Netafim USA takes in raw dairy wastewater, filters out fine particles that would otherwise clog irrigation lines and spoon-feeds a precise mixture of filtered lagoon water combined with fresh water directly to a crop’s root zone. This direct, targeted irrigation approach increases the crop’s water- and nitrate-use efficiency. (Sustainable Conservation)

While innovation is happening on a small scale, research is also continuing to help guide the agricultural industry’s participation in reducing nitrate and to inform possible enforcement down the road.

The basics of how to reduce nitrate leaching are pretty well understood, says Thomas Harter, a hydrologist at the U.C.Davis, and a lead author on the university’s report to the state water board.

U.C. Davis has done a lot of the research growers rely on to keep up with best practices, says Karen Ross, secretary of the California Department of Food and Agriculture. Still, she says, “In a state like California, trying to create that kind of precision tool for 400 crops in all of the different microclimates and different soils that we have is challenging.” Making that task somewhat easier is the fact that just 20 crops make up about 90 percent of the acreage, says Harter, so the research has focused intensively on the needs of those plants.

Growers follow that research assiduously, says Klassen. “What we preach in all of our meetings are the four Rs: right place [where on the ground so roots take nitrogen up], right time [when the crop is using it], right amount in those applications and the right product.” The last refers to different commercial mixtures formulated for particular plants.

Despite this knowledge, the Harter report found that, even in optimal circumstances, crops just take up 80 percent of the nitrogen applied, meaning 20 percent would still be running off.

Klassen is skeptical of that finding. “It’s site-specific,” he says. “We’re taking more data points to verify.” Agriculture groups funded by grower dues are paying for field studies and modeling. “In five to six years we’ll have that research done to correct that assumption that we’re causing groundwater contamination,” Klassen says. He points the finger of responsibility at his predecessors: “A lot of what was in the groundwater now was on the surface 10, 20, 40 years ago. We are seeing the effect of what were probably shoddy practices in the ’60s and ’70s.”

If the findings don’t bear that out, the state will require growers to adjust their practices to stop polluting. While applying less fertilizer could be a boon to farmers, helping them save money, farmers use fertilizer for a reason, says Klassen: to produce higher yields.

Ultimately, the water boards will enforce clean water rules on polluters, says McConnell. “We’re working toward nitrogen targets, figuring out which practices are protective,” she says. “And once we have the science and documentation behind it, [compliance] will then be required.”

Not Enough

There are some groups who won’t be waiting years to see if the state begins to enforce regulations against agricultural polluters.

“We are claiming that the state of California has a ‘pattern and practice’ of turning a blind eye to agricultural pollution and is ignoring its duty to protect the public and the environment,” says Steve Shimek, executive director of the environmental nonprofit The Otter Project, based in Monterey.

Shimek’s organization is part of a coalition of environmental justice, coastal protection and fishery groups that filed a lawsuit against the state at the beginning of August, contending that the State Water Resources Control Board and the Central Valley Regional Water Quality Control Board have failed to enforce clean water laws that are meant to prohibit agricultural pollution.

“The state board has to start regulating,” Shimek says. “It can’t just walk hand in hand with industry.”