Restoring Water Quality with TMDLS

Restoring Water Quality with TMDLS

Ariel Rubissow Okamoto

Pesticides, Sediment, Toxic Creeks, Water Boards, Napa County
See-Session-PowerpointsSOE2013-cover100px2When contaminants are coming from so many sources – whether it’s farm fields or urban areas or eroding creek banks, not to mention drains and discharge pipes – balancing actions to curb them can be a daunting task for water quality watchdogs. To this end, however, the two regional water boards charged with protecting Central Valley waterways and San Francisco Bay from contamination have effectively wielded the “TMDL.”  This Clean Water Act tool allows the boards to set a total maximum daily load of a contaminant for an impaired water body, and to work with diverse sources to reduce the load collectively. Such efforts often inspire new regulations, and a suite of related outreach and prevention programs. In this afternoon session, speakers described their experiences managing two priority contaminants – pesticides from agricultural irrigation upstream and urban creeks downstream, and sediment in the Napa River watershed.

Slide: Kelly Moran
First speaker Joe Karkoski, an engineer with the Central Valley Water Board, described how the Board adopted basin plan amendments to address diazinon and chlorpyrifos in the Sacramento, Feather, and San Joaquin Rivers, as well as the Delta, in the early 2000s. Those amendments included TMDL allocations, implementation provisions, and monitoring requirements for irrigated lands.

To be more specific, the Board set water quality objectives of 0.10 ug/L for diazinon and 0.015 ug/L for chlorpyrifos, and reached out to the Central Valley’s 35,000 farmers to meet them. “We monitored, we assessed, we made regulations. But just having a regulation doesn’t mean it gets implemented,” said Karkoski. “It’s not enough to create incentives, we also need new tools to get things done.”

Using the tools available, the Board encouraged agricultural coalitions to take a variety of pollution prevention steps related to pesticides and erosion. These included switching from furrow or flood irrigation to drip irrigation and micro-sprinklers; building sedimentation ponds; and doing a better job of managing tailwater return systems. The Board also worked with the Department of Pesticide Regulation (DPR), which in turn created some new dormant spray regulations. Among other things, these required anyone spraying fruit trees during the dormant cool season to maintain100-foot buffer zones from waterways, and prohibited spraying during a storm. More importantly, if alternative pesticides are used, they can’t cause a water quality problem, explained Karkoski.

Since 2004, there are far fewer exceedances of water quality objectives for the two pesticides, thanks to the program. But pyrethroids, their main replacement, now exceed objectives for water 40-50 percent of the time, and can be just as toxic to some aquatic organisms. “You can spend a lot of time in the weeds monitoring, but what we really need is to spend more time anticipating,” said Karkoski. “If you stop paying attention, problems are probably going to reoccur. We need to deal with not only particular contaminants, but also with pollutant pathways, and figure out how to sustain positive results.”

Up to 100 times more pesticide runs off from roads, sidewalks and other hardscapes than from vegetated softscapes.  Image credit: Kelly Moran.
Up to 100 times more pesticide runs off from roads, sidewalks and other hardscapes than from vegetated softscapes. Image: Kelly Moran.
The second speaker tackled the same pesticide problems but on a more urbanized landscape. The alarm bells went off when monitoring revealed widespread toxicity in 35 urban creeks in the Bay Area, results replicated around California, explained Kelly Moran of TDC Environmental. In the 1990s, they pinpointed the cause of this toxicity: diazinon.

Manufacturers agreed with U.S. EPA to end sales of all urban products in 2004, and diazinon use plummeted in Sacramento and the Bay Area. “Diazinon in our creeks dropped to zero three years after the ban,” said Moran. Various pyrethroids replaced diazinon as the active ingredient in many urban pesticide products. “Unfortunately we just traded one type of toxicity for another.” Indeed, Bay Area use of pyrethroids tripled in four years, and toxicity climbed again.

The San Francisco Water Board, with Moran’s help, was ahead of the game. In crafting its 2005 TMDL for diazinon, it recognized that there was a general problem with pesticides and built in a more big picture approach. “This was not a traditional TMDL. This TMDL addresses future pesticide related toxicity, and promotes integrated pest management,” said Moran.

“It’s not about lawn and garden pesticides, it’s about pesticides used around buildings, much of which are sprayed in urban areas on impervious surfaces, ” said Moran. And the main reason city dwellers are using pesticides is not to control fleas or mosquitos or termites, but to control something much more harmless: ants.

Concerned about the water quality impacts of all this spraying, the TMDL team suggested that DPR consider actions to reduce pyrethroids in runoff. At the time, product labels directed users to apply pesticides in a 10-foot wide spray zone around buildings to prevent ants. DPR determined to restrict the spray zone on pyrethroids to two feet, rather than 10, which is just as effective.

DPR also broadened its view on new product registration. “The big fix has been getting DPR to ask a question it never asked before: will this product cause water pollution?” said Moran. On the federal level, EPA has also improved its pesticide review process.

Indeed this “untraditional” pesticide TMDL has led to landmark changes, said Moran, including California regulations coupled with special restrictions placed on bifenthrin (the most environmentally persistent pyrethroid) that are together expected to reduce pyrethroid-caused toxicity by 80-90 percent.

“We built a team that coordinated water quality and pesticide regulation for the first time, and included wastewater and stormwater dischargers. All it takes is a good structure, a good plan, and education,” concluded Moran.

Leigh slide 5
Vineyard development above City of St. Helena drinking water supply, 1989. Image: USDA-NRCS

Education also featured strongly in the Napa County Resource Conservation District’s efforts to curb sediment pollution to the Napa River, according to the third speaker Leigh Sharp. Expansion of vineyard development from the valley floor to the hillsides was common in the late 1980s and increased erosion. In the early 90s, facing declines in salmon and steelhead and a threat to aquatic habitat, the regional water board listed the Napa River and its tributaries as water quality impaired for excessive sedimentation. The problem even made the news when sediment from a newly developing vineyard slid into St. Helena’s drinking water supply. “You can’t use the same erosion control practices on hillsides as you do in the flatlands,” said Sharp.

Next, the local community got to work and passed a hillside ordinance that requires any property developed on an over five percent slope to have: an engineered erosion control plan; appropriate winter cover crops; and setbacks from forests and creeks, among other things. As a result, Sharp calls Napa “the most regulated agricultural community in the state, perhaps the nation, with over 14,000 acres of hillside vineyard under erosion control plans.” In the early 2000s, the water board launched their TMDL process and began studying the multitude of factors that limit salmon and steelhead production in the Napa River watershed.

At the same time, the community continued to voluntarily form watershed management groups, implement fish-friendly farming practices, and develop a program called “Napa Green.” According to Sharp, “They wanted certainty and some control of their own destiny, they wanted to get ahead of more regulation.”

Instream salmonid habitat and winter refugia created as part of the Napa River Restoration Project. Image credit: NCRCD
Instream salmonid habitat and winter refugia created as part of the Napa River Restoration Project. Image: NCRCD

As a result, according to Sharp, “in many aspects, the community is now exceeding the requirements of the sediment TMDL.” Local interests are restoring thirteen miles of predominantly privately-owned Napa River frontage through public-private partnerships, removal of fish migration barriers, developing sustainability plans through a variety of third-party programs, and implementing priority erosion control projects in tributary watersheds that support threatened steelhead. More than 80 miles of habitat have been made more accessible to fish in just four years. “There have been a lot of bottom-up creative approaches because the community recognizes that sediment isn’t the only problem. Many vineyard owners voluntarily rededicate portions of their land to the river to reclaim,” said Sharp.

Results from five years of out-migrant fisheries monitoring demonstrate that steelhead in the Napa River are now relatively large and smolt production fairly consistent. These are good signs for the Napa River watershed, but there is more to do, said Sharp. Napa County, US EPA, and other partners are investing in development of a TMDL accounting system, for example, the success of which will depend upon cooperation from stakeholders, regulatory agencies, funders, and policy makers. “I don’t think you can write a regulation that would spawn this level of effort. The greatest benefits of the TMDL were the conversations and the relationships that happened – the mixing zone between information and action.”

Central Valley Irrigated Lands Program
Central Valley Board TMDLs
Urban Creeks Pesticide TMDL
Napa Watersheds

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Karkoski Slides

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Karkoski Slide 18


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Moran Slides

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