Watersheds

Introduction
All plants and animals (including humans) depend on water for life. The cleanliness of the water in our environment impacts our lives in very obvious ways. Many rural people drink groundwater (from wells or springs) without any treatment, assuming that it is clean and pure. Even city water supplies which treat their water merely remove biological organisms and large particles. Most chemicals which contaminate these city water supplies carry through the treatment process and are consumed by the public.

Water quality is also important from an environmental point of view. Many aquatic animals are unable to survive in polluted creeks and rivers. In particular, our region has a tremendous diversity of mussel species, many of which are very sensitive to water pollution, so a decline in our water quality could drive these species to extinction.

There are several basic concepts that I will assume you understand in the following discussion of Wortroot's water quality. When water falls as precipitation, some of it sinks down into the ground and becomes part of the groundwater. Groundwater can flow back to the surface through springs or may be reached by wells. Other water flows across the land's surface and becomes surface water. Surface water includes creeks, rivers, and lakes. A watershed is the land area from which a surface water supply is fed.

Surface Water
All of the water in Wortroot ultimately flows into Raccoon Branch, which then flows into Boozy Creek. Boozy Creek flows into Reedy Creek which eventually flows into the South Holston. So the quality of Wortroot's water influences (to a small extent) the quality of the water in the South Holston.

On a smaller scale, the water in Wortroot's creeks is influenced by the surrounding region. The map below shows the watershed which feeds Wortroot's portion of Raccoon Branch. The boundaries of Wortroot are outlined in red while the watershed boundary is outlined in blue.

Wooded areas at the time of this map's production are shown as green. After the map was produced, some land use changes occurred. The majority of Wortroot is now wooded, but more of the surrounding area has turned into pasture.

As you can see, over half of Wortroot's watershed is wooded, which promotes good water quality. However, the many steep pastures in the watershed are problematic. Without streamside buffers (strips of forested land along the sides of creeks), animal waste from these pastures flows down into the creeks and degrades the water quality.

Even on Wortroot's own property, there is a problematic area. Ideally, a buffer of trees should be maintained along the sides of Raccoon Branch in the meadow. The buffer should extend a minimum of 25 feet on either side of the creek. Streamside buffers slow the flow of water so that contaminants will drop out before the water enters the creek. In a later section, I have listed some resources for developing streamside buffers.

Groundwater
In most areas, groundwater is purified as it slowly trickles down through the soil, leaving impurities behind. In these cases, it is much purer than surface water and is usually safe to drink without treatment. However, in karst regions which include caves and sinkholes, water can flow directly from the surface to the groundwater without being purified.

The sinkholes along the road east of Wortroot are very problematic from a water quality standpoint since they are currently being managed as pastures. Water, including cow wastes, can flow straight down the sides of these sinkholes and into the groundwater. The groundwater from these sinkholes is likely to flow directly under Wortroot and could possible re-enter the surface water supply, causing water quality problems.

Health of Wortroot's Creeks
I used a macroinvertebrate sampling method to assess the health of Raccoon Branch, Wortroot Creek, Grave Creek, and Willow Creek. This method is based on the Izaak Walton League's National Save Our Streams Program and involves counting macroinvertebrates (insects, worms, crustaceans, and mollusks) in the creek. The diversity of macroinvertebrates can be used as a relatively reliable indicator of stream health since polluted creeks will have few macroinvertebrates living there.

I surveyed fourteen sites, most of them in August, but also one in January. During each survey, I identified all macroinvertebrates in a roughly 9 square foot region of the stream. I chose riffle areas where the water was moving rapidly and tried to choose areas with at least some large rocks. I surveyed two sites along Grave Creek, four sites along Willow Creek, three sites along Wortroot Creek, three sites along the southeast end of Raccoon Branch, and two sites along the northwest end of Raccoon Branch.

A water quality rating for each site was calculated using the following method. First, the types of macroinvertebrates found were divided into the following groups. (I have listed only those types found at Wortroot.)

Sensitive	Somewhat-Sensitive	Tolerant
caddisfly larvae	crayfish	aquatic worms
hellgrammite	damselfly nymphs	midge larvae
mayfly nymphs	dragonfly nymphs
gilled snails	scuds
riffle beetle adult	fishfly larvae
stonefly nymph
water penny larvae

Next, the water quality rating of the site was calculated, as follows:

(# of sensitive types X 3) + (# of somewhat-sensitive types X 2) + (# tolerant types X 1) = water quality rating

So, for example, at one site I found the following organisms: gilled snails, mayfly nymphs, caddisfly larvae, dragonfly nymphs, riffle beetle adults, stonefly nymphs, midge larvae, and water penny larvae. So I calculated the water quality rating as:

(6 X 3) + (1 X 2) + (1 X 1) = 21

Finally, I averaged the water quality ratings for each stream segment, resulting in the values shown below:

Streams are rated as follows:

Excellent = > 22
Good = 17 - 22
Fair = 11-16
Poor = < 11

As you can see, most of the streams on Wortroot are rated as good, though Willow Creek is only rated as fair. This is somewhat disappointing since Wortroot's creeks should be in the excellent category.

I did not do statistics on the results, so it is possible that the trends toward lower diversity in southeast Raccoon Branch and in Willow Creek are merely due to chance. However, I will assume for the moment that they are accurate representations of the diversity of macroinvertebrates in the streams.

The relatively low ratings of Willow Creek and of the southeast portion of Raccoon Branch could be the result of several factors. First, it may be merely an artifact of sampling in the case of Willow Creek - this creek is small and thus may not attract as many insects as larger creeks do.

The second possibility is potentially more troublesome - since the majority of the watershed for both of these creeks flows out of steep pasture, the water quality may be degraded. It is telling that Grave Creek is much smaller than the the southeastern portion of Raccoon Creek and is equivalent to Willow Creek in size, but has a slightly higher diversity than either. As you can see from the watershed map, a larger percentage of Grave Creek's watershed is forested compared to the watersheds of the other two creeks.

Finally, it is possible that the lower diversity in some creeks is due to chance since I sampled relatively few areas in each creek. In addition, floods washed out all the creeks in the fall and may have lowered the diversity of macroinvertebrates. In any case, it is worth keeping an eye on the diversity of macroinvertebrates in all the creeks, especially if land use in the watershed changes.

Resources
The state of Virginia is seeking to improve the water quality of the state through its Agricultural BMP Cost-share Program. They describe their program as follows:

This program funds up to 75% of the cost of implementing conservation practices to protect water quality. There is a maximum payment of up to $50,000 per farm. This program requires a minimum of 25 feet of fenced buffer around streams. The main benefits of this program are: the stabilization of streambanks from livestock, creation of forest buffers, and reduction of non-point source pollution.

To find out more about the program, contact your Soil and Water Conservation District Office at:

95 US Highway 23 S, Suite 1, Gate City, VA 24251
(276) 386-2323 or (276) 386-9241

It would be of great benefit to Wortroot to ensure the health of its watershed. If neighbors could be convinced to create streamside buffers, the quality of the water would improve greatly.

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Last updated 9/04.