This project will explore and explain water quality testing done over a period of time in Wenas and Umptanum Creeks. Three tests were done which help researchers to determine the general "health" of the streams. Turbidity, suspended sediment, and the nitrate levels were carefully measured using Depth and Width Integrated Samples.
The Wenas and Umptanum Creeks
Due to man’s influence, Wenas Creek is more polluted than Umptanum Creek. These two streams lie in drainages adjacent to each other and empty into the Yakima River. They are only a few miles apart but are vastly different in many ways. While they both basically are fed from the same snow pack and rainfall, the paths that their streambeds take have a marked affect on the quality of the water in each stream. Umptanum Creek is a free flowing stream that runs through rugged, undeveloped terrain. Wenas Creek, in contrast, begins in an area influenced by logging, flows into a manmade lake, and then continues through a valley of agriculture, livestock, and residential development.
Depth and Width Integrated Sample
A Depth and Width Integrated Sample is a water sample taken in such a manner that a small portion of the total sample is taken at each level of the stream- surface, mid-flow, and near the bottom. This process is repeated several times across the entire width of the stream. This method gives the most accurate sampling of the entire stream flow. Results of the testing done for this study are presented in graphic form later in this project.
Turbidity is a measure of light scattered in water. It is caused by solids suspended in the water, whether mineral or organic. In general, turbidity is the cloudiness of the water. It is a good indication as to the presence of potential pollutants.
The test for suspended solids measures the weight of material in a given volume of water. High concentrations of particulate matter can increase sedimentation and siltation in a stream. This can change the habitat for bacteria and other aquatic life.
The measurement of nitrates present in stream is a good indicator of the total nutrients in the water. Nutrients are essential for growth. In most instances, growth is considered to be beneficial, but this is not necessarily so in a stream. Algae and other plant growth enhanced by nutrients can be good up to a point, but can easily over-populate and become a nuisance. Many things affect stream nutrients. Temperature, decomposition of organic matter, and lawn and garden fertilizers are just a few of these things.
Ryan Anderson, an environmental specialist for the Washington State Department of Ecology, has been very helpful in the research of this project. He provided the test kits and materials for the experiments, and has given much information for the improvement of this project.
This report will be arranged in the same way that the water flows. The headwaters of the Wenas and Umptanum Creeks are only about eight miles apart and are mostly snow and rainfall fed. Both streams flow in an easterly direction to end up pouring into the Yakima River.
These streams originated in the forested foothills of the Eastern Cascades. When water falls in a forested area, most of it does not penetrate the canopy of the forest. Over half of the water never reaches the forest floor. It mostly evaporates and transpires back into the atmosphere. The water that does reach the ground "slowly percolates down through the forest soil and some of the rain runs over the surface of the soil and enters the waterways." This can cause problems, such as soil erosion, as is explained later.
By removing trees through logging, the canopy of a forest is damaged or destroyed, which can cause soil erosion. Soil erosion is caused by many things, including removal of the canopy, road runoff, and the ground disruption caused by the heavy equipment used in a logging operation. Logging affects soil erosion in that when there is not a forest canopy, all of the precipitation that the area receives will fall to the ground, and a large portion will runoff, and eventually end up in a stream. This will cause a higher turbidity and suspended sediment in the waterway that the runoff enters. In this paper, it is assumed that since the headwaters of the Wenas and Umptanum Creeks are close together, the effects of logging on water quality are roughly the same in both streams. Top of Page
The Wenas Reservoir is a manmade lake in Wenas Creek. Damming a stream turns the free flowing creek into a still body of water. This can have an effect on several aspects of water quality. In the warm months of the year, the sun will heat still water. Warmer water can encourage algae growth, which can, in turn, change the color of the surface water to a pea-green shade. Other aspects of the lake, as they relate to water quality, include its use for recreational boating and fishing, and lakeside development. Small amounts of gasoline and other human litter may find their way into the water, which could increase the turbidity. Below the dam, Wenas Creek then flows through several miles of mostly agricultural area. There are several things about agriculture that can affect water quality. These include the effects of fertilizers, pesticides, and herbicides. Livestock, soil tillage, and irrigation are other major factors.
Irrigation in the Wenas Valley is basically done two ways; ditch or "rill" irrigation, and sprinkler irrigation. Rill irrigation is accomplished by making furrows in the land with a tractor. Water is then flooded into these ditches. This method of irrigation causes more soil erosion than sprinkler irrigation. Sprinkler irrigation is more rain-like, and more of the water is absorbed into the ground, instead of running off. Since the Wenas Valley lies in an arid desert, constant irrigation is needed to grow crops. Irrigation runoff can add to suspended sediment, turbidity, and possibly the nitrates in a stream, if the ground was fertilized. Wenas Creek has irrigated fields along almost its entire length. Umptanum Creek has no development or farming, and no irrigation in its drainage.
In agriculture today, fertilizers, pesticides, insecticides, and herbicides are all commonly used. These chemicals can be transported into streams by rainfall, irrigation, or snow runoff. Since the Wenas Valley has many agricultural fields, it is reasonable to conclude that some of the chemicals used on these fields eventually end up in Wenas Creek. In contrast, Umptanum creek flows through rugged, undeveloped country; it has no exposure to agricultural chemicals.
Agricultural fertilizers are mostly made up of nitrogen. These compounds are regularly applied to fields. Rainfall and irrigation transport most of the fertilizer into the ground. In places where runoff is common, this nitrogen can be washed away with the soil and eventually end up in adjacent drainage ditches. Ultimately, this nitrogen-rich runoff finds its way into the stream. The nitrogen that is in the ditch water, when added to the stream, can raise the nitrate level in the waterway.
Nitrate and turbidity levels are affected by the exposure to livestock. There are many cattle operations along the entire length of Wenas Creek. The cattle operations of the Wenas Valley affect the nitrate levels of the Creek in that the cattle manure raises the nitrate levels of the creek. At certain points along the streams, there is much cow manure on the banks. This can cause higher levels of nitrates and nutrients. If too many nutrients are in the water, algae can live and develop, and algae growth increases the turbidity in a stream. Also, in researching this paper, many observations of stream bank destruction were found due to cows. This stream bank destruction causes erosion, which can lead to higher turbidity and suspended sediment.
In farming, any time the soil in a field is tilled, it is loosened and more easily eroded. When the soil is loose and it rains or the field is irrigated, some of the loose soil will runoff and eventually drain into a stream. This will cause suspended sediment and turbidity to rise. Since the Umptanum area is undeveloped, no soil tillage is taking place. The valley that the Umptanum Creek lies in is mostly sagebrush. On the other hand, the Wenas Valley is mostly fields and farming is widespread.
As Wenas Creek continues toward the Yakima River, it flows through miles of residentially developed area. Residential development can have many effects on water quality. Issues here include road runoff, septic systems, pesticide and fertilizer use, and disruption of the soil for construction. There is no residential development on Umptanum Creek.
Wherever there is development, there are going to be roads, and along with roads come road runoff. Runoff is what happens when it rains and washes road tar, tire rubber, and oil off of the road and into roadside ditches which eventually drain into nearby streams. The substances washed off the road can add to nitrate and turbidity levels in the stream.
Human wastes from the residential development in the Wenas Valley are dealt with by septic systems. Untreated wastes, detergents, and other household chemicals are flushed into septic tanks and are filtered by the surrounding soil. While septic systems are designed to filter water before it returns to the groundwater, it is possible for some of these wastes to make it into the creek. This is especially a concern where the development is very close to the creek. This could have an effect on the nitrate levels in the Wenas creek.
As with the agricultural chemicals previously mentioned in this report, the same problems exist with residential pesticides and fertilizers.
As these residences are built, soil is disrupted and displaced, exposing it to erosion, which can lead to higher levels of suspended sediment and turbidity in a nearby stream.
Importance of Water Quality
Water quality is important for the environment because water is the basic element of all living things. If polluted water is present, this will affect the health of the plants, animals, and other organisms, including humans, which come in contact with it.
Water quality is a very important issue for human health and wildlife. Testing water quality is the only way to determine the amount of chemicals that are being added or dissolved into a stream. Scientists, planners, and developers need to know about changes in water quality. The health and well being of citizens depends on it.
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