WATER QUALITY IN EASTERN NORTH CAROLINA
Presentation to the February 19th NC Pork Conference
NC Division of Water Quality
I’ve been asked to discuss the water quality in Eastern North Carolina. The usual question that most people want answered is whether water quality is getting better or worse. Which answer would you prefer hearing? In many water quality issues in the state, I can actually provide any answer that is sought, and then back it up with scientific evidence, as long as I’m allowed to focus only on the evidence that I choose. It’s similar to the popular political questions on the health of the US economy. If you look around Kannapolis, NC, you’d probably get a much more dire reading on the economy than if you looked at evidence from Wall Street. In most water quality matters, I could provide evidence that is completely contradictory to evidence presented by another “expert.” But, I’m not up for election and I don’t get paid enough to perjure myself, so I will try to provide a honest response, based on the best information available to me.
When researching the water quality in any basin, I must first determine the criteria that will be used in making my overall assessment. This is the key and will directly impact the answer that I provide. An honest assessment of water quality in Eastern NC can only be provided by first answering critical questions such as these below:
· Do I concentrate on the data available on the mainstem of the river or do I include small creeks and embayments that might be showing problems not being seen in river mainstems? Sometimes localized pollution sources in a small stream can cause severe problems that are not seen river wide.
· In the case of many of North Carolina’s rivers, do I consider the quality of the sounds or just evaluate a few riverine stations?
· Do I just look solely at surface water or should I include groundwater?
· What parameters do I use to determine the health of a river? Do I use sediment, dissolved oxygen, fecal coliform, nutrient concentrations, metals concentrations, average algae biomass levels, shellfish closures, swimming beach closures, fish populations, fish kills, diversity of fish species, or small aquatic insect assessments?
· Do I look at the past two years’ data, ten years’ data, twenty or more? How many years of incline or decline are necessary to show a definite trend?
· Do I try to determine if stormwater runoff is getting larger or smaller?
· Do I consider improvements or degradation caused by hurricanes? How do I remove that data that is not to be considered?
· Do I look at how many miles of good quality habitat that has been destroyed in recent years?
· Do I look at the number of municipal, industrial or agricultural spills that occur, even though we don’t usually measure the water quality impact of these spills?
· Should I in any way consider the potential for pollution by increase in potentially polluting activities?
There is no one method to assess water quality and when someone presents evidence of a trend based on a narrow data focus, I know to be cautious. It’s like I mentioned before, it’s tantamount to someone relying on one economic indicator to define the health of this country’s economy.
In evaluating longer-term trends in water quality, a critical variable that must be considered is the annual precipitation. Precipitation can change drastically from one year to another and can go in seemingly unprecedented cycles that last for several years. If, for example, we were trying to look at the impact of runoff from agriculture operations during the 1995-2001 years, we should see a significantly reduced impact due to the significantly reduced rainfall seen in those years. Similarly, I remember seeing information from the Chesapeake Bay that showed that during the extremely wet year of 1996, after spending hundreds of millions of dollars to reduce nutrient contributions by installing BMPs, the loading of nitrogen to the Bay was about 50% greater and phosphorus 100% greater than the past 10 year loadings. The impact of these loads were seen in the next year’s algae growth levels but should they be taken as a sign that the Bay was going down in water quality?
In another instance, a study was done on the Yadkin River based on 40+ years of suspended sediment data, to attempt to determine if there was a trend in sediment concentrations or loadings. Deriving an answer was not as straightforward as you might think. The data shows that if trends in rainful were up, the river’s sediment loading could go for years showing an upward trend. If an analysis had ended after those years, the conclusion would have been that things were getting significantly worse. On the other hand, during drought periods, the data showed that suspended sediment levels would be significantly lower than previous years, leading to an incorrect conclusion that the quality was getting better. It took an enormous and potent amount of statistical analyses to determine that there was an overall decline in sediment concentration during the past 40+ years. In many of our streams, creeks, rivers, lakes and estuaries, we do not have the comprehensive data required to analyze trends, although trends could be occurring.
Another fallacy in looking at trends is that analytical data capabilities are frequently improved. This places previous data in question. For example, a method that the state employs in measuring eutrophic conditions, the chloropyll a test, has changed, and hopefully improved, over the years. Because of analytical changes, some of the previous data is questionable. What does this say about the veracity of long term trends that were based on the old analytical method? Another dynamic is in our capability to detect chemicals such as mercury or dioxin. Historical data reports, based on old testing methods, might have indicated “not detectable.” But, better analytical techniques reveals the presence of these “previously undetected” chemicals. Does that indicate that the water quality is getting worse? Was a violation in a water quality standard not there thirty years ago or just not seen?
During my presentation, I will look at the available data that we have about several of the major river systems seen in Eastern North Carolina. I will present evidence might indicate that there is no downward trend in overall water quality of these waters. One of the most critical water quality measurements that relates to animal operations is nitrogen levels. I will present several assessments that indicate a downward trend in nitrogen levels in the eastern rivers. However, I will also present evidence that shows things might not really be improving. I will present evidence, or a lack of evidence, that groundwater is being adversely affected by the animal waste industry.
In my presentation, I will review evidence that indicates that we should be seeing significant improvements in the waters of Eastern North Carolina and why or why not this has been seen in the field.