The Centralia Lake is located 2 miles south of Centralia, Kansas, USA. This 400+ acre lake in the northeast corner of the state was completed in 1991 and stocked with fish that year. It is controlled by the City of Centralia with picnicking, swimming, camping, boating, and fishing facilities. The dam is at the east side of the lake with an arm to the southwest and another to the northwest. Between the two is the picnic area. The swimming area is along the southwest arm and camping along the northwest. Being an agricultural region, there are surrounding fields and also, a hog farm to the north. There is a wide zone of lake property between the agricultural areas and the shore line. B&B High School is about 12 miles north of the lake.

Since this lake is used by many people for a variety of recreational activities, maintaining healthy water is important. The chemistry class at B&B High School, set out to find if the surrounding land was impacting the water of the lake.

The class measured nitrate, dissolved oxygen, pH, phosphate, temperature, turbidity, total solids, elevation and coordinates at each of six locations at a depth of 2 feet.

Materials: HACH water test kit, simple water samplers and a secchi disk made at school, digital thermometer, digital conductivity meter, pH meter*, GPS unit**, boots

* Thanks to Paul Strathman, Nemaha County Rural Water District, along with additional equipment.

** On loan from Emporia State University

Even with a chilly day, the results were observed easily.

Temperature influences how much oxygen can be dissolved the water, how fast algae and aquatic plants photosynthesize, rate of metabolism of aquatic organisms, and the degree of sensitivity that organisms have to toxic wastes, parasites, and diseases. Cold water can hold more oxygen than warm water. Warm water has a negative affect on the water quality by speeding up organisms' metabolism, causing them to need more oxygen. The aquatic plants can not produce enough oxygen. Although the higher temperatures increase the rate of photosynthesis and plant growth, these plants die and decompose, consuming more oxygen. The sites along the south shore varied about 0.4 degrees from those on the north.

The pH of the water indicates its acidity or alkalinity. It is affected by such things as automobile and coal-fired power plant emissions, in addition to dissolved minerals from ground water and field runoff. The pH can have a negative affect if it varies too far from neutral 7. The Centralia Lake pH averaged 8.2 at each location.

Oxygen becomes dissolved in the water through wave action mixing the water with the atmosphere and also through photosynthesis by plants . High levels of dissolved oxygen (DO) are positive to the environment because aquatic plants and animals with gills get their oxygen from the water. Warm temperatures with little movement of the water result in low oxygen. Cool weather with rain and wind help mix atmospheric oxygen with the water increasing the DO. The Centralia Lake averaged 19 PPM DO with little fluctuation between the sites. This is supersaturated DO at the 13.6 degrees C average temperature of the lake.

Turbidity is caused by the suspension of particles in the water preventing light from penetrating the water. Turbidity may be caused by soil erosion, urban runoff, wastes, algal growth, or too many bottom feeders that disturb the water sediments. A high turbidity causes the water to warm which decreases the DO in the water. The water can no longer support a large amount of aquatic life. Photosynthesis decreases also because of the low light, decreasing the DO even more. The average tubidity of the water at the Centralia Lake was 1.5 feet. The fluctuation of tubidity between the six sites was only 0.5 ft.

Sewage is the main source of nitrates. Other common sources that can or high amounts of ammonia and nitrates include runoff from fields, dairies, feedlots, and barnyards. Too many nitrates in the water supply has a negative affect. It can cause a serious condition called “blue baby” syndrome. It prevents the blood from carrying enough oxygen and effects babies more readily than adults. Tests showed no nitrates in the water at the Centralia Lake.

Phosphorus in water comes from animal wastes, industrial wastes, and fertilizers. Too much phosphorous in the water supply can have a negative effect on the environment. It encourages the growth of plants rooted in the water and algae which in turn increases the rate of cultural eutrophication of the water. This means that the water is aging faster than the rate at which it naturally would. The condition arises in which the oxygen in the water is completely used up. The lake’s phosphorus levels averaged 0.4 mg/L. The phosphorus with one site showing no phosphates.

Therefore, using the guidelines from the Field Manual for Water quality Monitoring, the class has decided the Centralia Lake water quality is good to excellent since the pH is fair, DO and turbidity is good, and nitrate and phosphate levels are low. The conclusion is that the surrounding fields and hog farm are not impacting the lake water.