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 chemical 
entering flowing water is an unavoidable consequence of the application. In

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 draw 
the line here. If we assume that the label ensures no or little impact, then

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.