Thursday, August 8, 2013

New Mexico: Brantley Lake State Park


Brantley Lake State Park, New Mexico


Unlike the majority of New Mexico's state parks, Brantley Lake is not one I'd go out of my way to visit, although that's exactly what I did recently.

But Brantley Lake State Park does have some stories to tell.

DDT

Remember DDT from back in the day, probably before you were born?

The link is to a wikipedia article, which does a good job of explaining the not-so-black-and-white issues about the pesticide in a reader-friendly way.

Some high points: 
  • DDT was used to control pests in agriculture and also to control insects that carried diseases such as malaria, plague, and dengue fever.
  • One problem with DDT application circa 1950s-60s was the lack of restraint in its application. Instead of being used strategically or with the least amount necessary to be effective, it was often applied in promiscuous quantities and locations. This resulted in unnecessary environmental damage and the development of resistance by the target insects. 
  • DDT was associated with the near-extinction of peregrine falcons and bald eagles and human toxicity, leading to illness. 
  • DDT was banned for agricultural use in the U.S. in 1972
  • DDT or its decomposing spin-offs attach to soil, and "depending on conditions, its soil half life can range from 22 days to 30 years."

DDT and Brantley Lake


Here is a 2006 advisory from the EPA:
High levels of DDT found in Brantley fish. Officials warn against eating channel catfish, walleye caught in lake. Carlsbad, NM -- Data released by the New Mexico (NM) Department of Health, Department of Game and Fish and NM State Parks and the U.S. EPA show that elevated concentrations of total DDT, a banned pesticide, has been found in channel catfish and walleye in Brantley Lake. A fish consumption advisory due to mercury contamination is already in place for several fish species at Brantley Lake, which also advised limited eating of channel catfish and walleye. The new advisory recommends against eating any channel catfish and limiting eating of no more than 4 ounces of walleye.

NMED officials said that although only a small amount of data is currently available, the concentrations of DDT are high enough to cause health concerns for people of all ages. A composite sample from five channel catfish had 1,761 parts per billion, which is more than three times the EPA's "do not eat" guidance level of 550 ppb. A composite sample of five walleye had 485 ppb. The source of the DDT, which was banned from the US in 1972, is unknown. Source: Current-Argus Staff Writer - February 4, 2006, http://www.currentargus.com/apps/pbcs.dll/article


In 2013, Stella Davis wrote a fine piece on Brantley Lake and DDT, published in the Carlsbad Current Argus. An excerpt: 
 How did DDT get into the fish in Brantley Reservoir? According to the State Environment Department, years ago, DDT was apparently used in the Pecos River valley for agricultural and mosquito control purposes. After being applied, rain probably washed it into the river, or it may have been directly applied to water (for mosquito control) where it tends to attach to the sediment. That's why bottom-dwelling fish, such as catfish, tend to have higher concentrations than fish that live higher in the water, such as walleye.

Between 2000 and 2003, the EPA conducted a nationwide study of contaminants in fish tissue in several hundred lakes. Brantley was one of the lakes included in the study. Total DDT levels in Brantley channel catfish were the highest of the entire study - more than three times the EPA recommended "do not eat" level. Brantley walleye were at the EPA recommended "no more than one meal in two months" level. The question often asked by avid fishermen at Brantley is, if DDT has not been used in decades, why are there still unusually high amounts of it in fish at Brantley Reservoir? The state Environment Department, in its fish consumption advisory questions and answers, says DDT breaks down into DDD and DDE. When experts talk about total DDT, they mean the total amount of all three. DDE is very stable and lasts a long time in the environment. The total DDT in Brantley Reservoir fish is almost entirely DDE, which means that it has been there for a long time.

No one knows for sure, but it is likely that DDT used over several decades accumulated in the sediment of McMillan Reservoir. After Brantley Dam was built, McMillan was drained and all the sediment was stirred up, releasing several decades worth of accumulated DDT (by then, probably mostly broken down into DDE) to be absorbed by fish when the sediment settled in Brantley Lake.

 Counter-intuitively, it is safe to swim in the lake.


Who owns the lake? 

The state owns the park. Another entity owns the water in the lake (in this context known as Brantley Reservoir).

Well, it owns the water to the "minimum pool level."

It looks like the Carlsbad Irrigation District might be the owner of the lake.

When the water-users (e.g. farmers) south of Brantley Lake need water for irrigation, the water management entity drains off water from the lake to supply their needs. 

Because of the drought in New Mexico, the lake level is already very low - not as low as it's ever been, but close. Fortunately, although there's been little rain this year at the lake, the land south of the lake has enjoyed some. This happy chance has reduced the need for pulling water from the lake.

What's "minimum pool level"? 

The "minimum pool level" is the lowest level to which a reservoir is allowed to drop. (Source: Irrigation Engineering - Basak.)  

One guide to establishing a minimum pool level is here: "the level of groundwater in the aquifer and the level of surface water at which further withdrawals would be significantly harmful to the water resources of the area".

Some of the above information I received from one of Brantley Lake's park rangers. 


Conclusions

If I had limited time in the area, I'd forego Brantley Lake and instead visit:  

I'd consider checking out Sitting Bull Falls also, but I haven't been there yet. It's about 30 miles west of Brantley Lake.

 








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