### NE Dept. of Ag comments on minimum thresholds Creger, Tim to: Jack Faulk 10/23/2009 03:09 PM
Cc: "Romary, Craig", "Goans, Steve"
History: This message has been forwarded.

Dear Mr. Faulk,

I would like to offer the following comments regarding minimum thresholds for the aquatic pesticides NPDES permits. These comments come from myself and my environmental programs specialist, Craig Romary. I think you'll find our comments are tempered somewhat by our perspective on High Plains geography, which means we have few large lakes but a lot of flowing streams, rivers and irrigation canals. I am copying Steve Goans at the NE Dept. of Envir. Quality so that he knows what our submitted comments were. We intend to work together to establish similar thresholds on NDEQ's state permits. If you have any questions, feel free to give me a call or send me an e-mail.

Regards,

Tim Creger Pesticide Program Manager Nebraska Department of Agriculture (402) 471-6882 tim.creger@nebraska.gov

From Tim Creger:

Aquatic herbicides applied in NE would include, but not be limited to, irrigation canals, farm ponds, privately held non-farm ponds, recreational lakes, runoff containment lakes (such as Offutt AFB), and streams and rivers.

Mosquito control applications would include both larval and adult stages of development, with the larval stage most likely to be applied to standing or open water, and the adult applications more likely targeting terrestrial sites that include or are adjacent to open water.

First and foremost I believe we need to write in exceptions/exemptions/exclusions (whatever term is required or palatable) for small scale private land owners, homeowners, and property managers. This audience is most likely to use over-the-counter pesticides that have low secondary toxicity, will make as few applications as possible, and will own or manage the smallest sized treatment sites. I am a lousy judge of surface area, but in my mind the average farm pond would probably range in the 1-10 acre size. There are a few NRD flood control impoundments that are used as water sources for cattle, but I've never seen any larger than half a section (320 acres). My impression of state-managed lakes and ponds is that they are typically more than 100 acres in size, but there are a few possibly smaller. Given these parameters, I think a reasonable threshold for standing open water treated to control mosquitoes (larval or adult) would be 50 surface acres. Anything larger seems like it would be prone to regular outflow due to springs or rainfall. As for flowing water treated for mosquitoes, I don't see that happening on any kind of regular basis, since flowing water is not good mosquito breeding habitat. If treatments are made to these areas, the applicators either don't understand the biology of the insect, or they are actually targeting the still waters along banks and ditches, and the chemicalentering flowing water is an unavoidable consequence of the applicatio n

. I n these sites, I believe it would be reasonable to set a threshold of 1-2 linear miles of stream bank, with the possible exception of roadside applications made to/over/near drainage ditches with flowing or standing water.

As for the aquatic weed control stuff, that really expands the potential list of target sites. Now we're talking irrigation canals/ditches/laterals, drainage ditches, private and public ponds and lakes, and probably more I am not thinking of right off hand. The irrigation sites could be treated when dry or filled, flowing or not. I venture to guess virtually every road in our state has some sort of drainage control system engineered into the roadbed, and they will carry water sometime during the year. The weed control applications would only be expected to be made in the growing season, but whether there is water present or not is actually the issue. Finally, ponds and lakes that are treated for aquatic or noxious weeds are everywhere. It is not cheap to treat a pond or lake for weeds, and all aquatic herbicide labels limit the treatment to no more than one half of the lake/pond volume per treatment, in order to avoid oxygen depletion and a subsequent fish kill.

Here's my thinking on each of the above sites: For irrigation canals/laterals/ditches, approach the threshold from the perspective of what the water will or might impact should treated water be released into a non-irrigation conveyance. That could either be a set number of miles upstream from the outlet of the canal, an expected length of travel for the treatment, or a percentage of water volume capacity of the canal/ditch. Most irrigation canal managers know the maximum volume of their systems, so if we were to say a NOI would only be required if the treatment was expected to enter into a non-irrigation conveyance, introduced within XX miles of the outflow point of the canal, or applied to greater than XX% of the total daily volume flow of the canal at the point of treatment, we would cover the bulk of the scenarios where treated water could impact non-target sites. As for the ponds and lakes, I don't know if we can use the same thresholds as for mosquito control or not.

Something I've heard and seen discussed recently is how different people view what the "treatment site" is. If the shoreline of a lake is treated for swimmer's itch or toxic algae, the treated water eventually dissipates throughout the water body, even though the majority of the lake is not treated. What starts out at 10 ppm a.i. at the shoreline on day 1 could result in 10 ppt in the center of the lake on day 5. The discussion becomes do you set your treatment thresholds at the specific area of initial treatment or the whole lake after dissipation? I think this speaks to the concept of "no toxics in toxic amounts", but I really don't know how to apply it to an intentional pesticide application, since FIFRA stipulates that once the a.i. no longer impacts the target species, it is not considered toxic, whereas others will argue that even trace amounts of the chemical are toxic to some sort of organism given the right conditions.

If it were me, I'd say the easiest measure to most applicators is the entire water body surface area, since most aquatic herbicide labels provide treatment rates in cubic volume, and that is much harder to estimate than an established surface area measure for the lake or pond.

From Craig Romary:

* I think we want to exclude those applications that we feel won't have potential for detrimental impact, yet still ensure that small, potetnially toxic, applications done thousands of times across the state in a given year don't have environmental impact. I'm still not sure how to drawthe line here. If we assume that the label ensures no or little impact

, t hen I think we can exclude certain applications from the NOI, and many of the other requirements in the permit. If they are small applications but for whatever reason we want to have a better idea of what is going on and include more controls, we could exclude from NOI yet still have some of the other requirements under the permit - whatever those are (IPM, BAT, recordkeeping, reports, etc).

* Another key is connection to waters of the state - some ponds aren't in a drainage way, per se, but could still overflow and drain to a stream. Same thing for more ephemeral road ditches that may have water present at certain times of year.

* The largest NRD impoundment listed in the 2009 fishing guide ( http://www.ngpc.state.ne.us/fishing/ guides/fishguide/FishGuide.pdf) is 250 acres, and there were only a couple out of 40-50 that were this large. Majority are 100 acres or less - many 10-15 acres. Many of the state WMA and state lakes are several hundred acres in surface area (500-900 ac)

* For mosquito applications, I think I would start at 15-20 acres over standing water, and 1/2 mile for more linear habitats. This would exclude most of the small acreage owner/landowner sites, yet keep the larger scale applications as needing some requirements under the permit.

* For aquatic weed control, I think it can be distinguished between submerged/floating aquatic vegetation (algae, pondweed (or canal weed), etc) and emergent macrophytes. The former could use a volume and/or surface area mark for the threshold; the latter could be "bank mile" or something. Because the former would include copper and some of the more 'heated' products for irrigation canals, the surface area or volume threshold may need to be smaller than we would like. Copper is on many states' list of pesticides of concern, I think, and things like acrolein are also on the radar (obviously). We could define these sites even more by using terms like flowing (lotic), impounded (lentic) to differentiate thresholds.

* For submerged/floating weeds in lentic/impounded systems, I think 5-10 acres would be a good threshold - this would exclude many small ponds and backyard goldfish ponds but keep most neighborhood association ponds/lakes and bigger operations. For submerged/floating weeds in lentic systems (irrigation canals), you could use a volume of treated water or percent of actual flow volume, etc.

* For emergent macrophyte weed control (cattails, phragmites, loosestrife, etc) in linear habitats, I think the 1/2 mile threshold would still work. It would exempt/exclude NOI for small operators/projects yet catch many of the bigger ones. Whether county or state roadside work and rail ROW work would fall here depends on the drainage and NDEQ's interpretation.