WATER QUALITY
Water quality consists of measurable chemical and physical quantities that are related to
intended water use. Water quality is perceived differently by different people depending upon
their designated use for the water. For example, most people demand higher quality for drinking
water than they would for irrigation water. This section focuses on water quality conditions in
the Higginsville City Lake Watershed and how they relate to intended water use.
Pesticides
As required by state regulations, DNR analyzed quarterly samples of finished drinking water
from the Higginsville City Lake. Atrazine, cyanazine, and metolachlor were detected in samples
taken between 6/6/94 and 6/10/96 (Figure 1). Two samples (6/6/94 and 9/13/94) exceeded the
Maximum Contaminent Level (MCL) of 3 parts per billion (3 ppb) for atrazine. Since compliance
is based on a four-quarter running average, the Higginsville system was out of compliance.
Cyanazine and metolachlor have Health Advisory Levels (HAL's) of 1.0 ppb and 100 ppb
respectively. MCL's have not been established for these compounds.
The Ciba Corporation hosts a voluntary water quality monitoring program. Under this program,
weekly water samples are analyzed for atrazine. Between 2/6/95 and 6/24/96, eighteen weekly raw
water samples (Martin, 1996) exceeded the MCL for atrazine (Figure 2). None of the finished
water samples taken during this period exceeded the MCL. The Ciba samples are analyzed for
total triazines (includes cyanazine and simazine ) by immuno-assay. The atrazine content is
estimated by applying a conversion factor to the total triazine concentration.
Interviews with producers (who farm over 57 percent of the cropland in the watershed) and
commercial applicators (who sell and apply pesticides in the watershed) revealed that atrazine
has been the most widely used corn herbicide in the watershed for several years. The popularity
of atrazine is due to low cost and consistent success at controlling a broad range of weed
species. Other herbicides and herbicide combinations can increase costs by 140 percent to over
400 percent and have not proven to be as effective at controlling weeds.
Grain sorghum, or milo, is produced in the watershed on limited acres. Herbicide and fertilizer
treatments are similar to corn. Few herbicides are labeled for use on grain sorghum. Since
atrazine is effective, economical, and approved for use on grain sorghum, atrazine is the most
frequent choice. Producers report that atrazine is used on at least 95 percent of the corn and
grain sorghum in the watershed. A University of Missouri study found that 95.5 percent of all
corn and 96.2 percent of all grain sorghum in Missouri is treated with atrazine
(Sievers & Fulhage, 1992).
The Higginsville Country Club Golf Course is immediately adjacent to the lake and does use
pesticides, particularly fungicides and broadleaf weed herbicides for turf pests. A pest
treatment program developed by the Scott Products company is used. Higginsville City Lake has
not been tested for the pesticide products used on the golf course.
Nutrients
Although many different plant nutrients are often present in surface waters, nitrogen and
phosphorus are by far the most important water quality indicators. Dr. John R. Jones,
University of Missouri, took surface water samples from Higginsville City Lake between 1989 and
1995. Three samples were taken four weeks apart between May and August each year of the
seven-year study (Jones, 1996). Jones analyzed for total nitrogen, total phosphorous,
transparency, total chlorophyll, and suspended solids.
Total nitrogen averaged 1,259 ppb (Figure 3). The high of 2,024 ppb was reached in 1990
and the low of 75 3 ppb was reached in 1989. These values are well below the 10 ppm
(10,000 ppb) MCL for nitrates.
Total phosphorus averaged 129 ppb (Figure 4). The high of 269 ppb was reached in 1993 and the
low of 44 ppb was reached in 1991.
The total nitrogen to total phosphorus ratio (Figure 5) averaged 12.2 over the period
indicating that plant growth in the lake tends to be limited by both phosphorus and nitrogen.
A number of likely nutrient sources were identified during reconnaissance of the Higginsville
City Lake watershed. The abundance of crop and pasture land in the watershed are the most
obvious sources. Numerous areas where livestock congregate for feeding, shade or salt and
mineral intake were found in or adjacent to drainageways. Fecal material dropped by drinking
or loafing cattle in a drainageway adds nutrients, organic matter, and bacteria to the water.
Livestock disturb the channel and streambanks creating soil erosion that adds sediment to the
stream system and water supply reservoir. Little or no buffering is present between cropland
and pasture nutrient and sediment sources and natural drainageways.
Failed private septic systems pose environmental concerns across the state. Failing septic
systems near Higginsville City Lake may pose particular hazards. Statewide, relatively few
older private septic systems with leach fields function properly. For more information on
nutrients and septic systems, see Appendix B.
Water Clarity and Solids
Water clarity is an important consideration for many intended uses. One of most simple and
widely used devices for measuring the transparency of water is the secchi disk. It is a black
and white wood, plastic or metal disk about 8 inches in diameter that is lowered into the water
being tested until it disappears. The depth at which it can no longer be seen is called the
secchi depth. Experiments have shown that sufficient light to support plant growth penetrates
to approximately 2.5 times the secchi depth.
Another important measurement related to transparency and algal growth is the chlorophyll
content of the water sample. Chlorophyll is the green plant pigment responsible for capturing
the sun's energy in the process of photosynthesis. Algal blooms can greatly reduce water
clarity under certain conditions. The chlorophyll content is related to the abundance of
phytoplankton, minute free-floating aquatic plants, in a water sample.
The amount of solids present in water is a consideration in its suitability for domestic use.
Waters with total solids content of less than 500 ppm are most desirable with standards
generally recommending an upper limit of 1000 ppm for potable water. Waters with a high solids
content often have a laxative effect on people whose bodies have not adjusted to them.
Sufficient nutrients are present in Higginsville City Lake to support plant growth that would
turn waters green however turbidity due to suspended sediment turns waters brown and limits the
light available for plant growth. Over a seven-year study period (Jones, 1996), summer surface
waters were never very clear.
Secchi depth (Figure 6) averaged 2.1 feet (0.64 meters) with a high of only 3.3 feet (1.0
meters) in 1989 and a low of 0.5 feet (0.15 meters) in 1990.
Total chlorophyll (Figure 7) averaged 18.0 ppb with a high of 28.0 ppb in 1993 and a low
of 5.8 ppb in 1990.
Suspended solids represent the undissolved portion of a water sample that remains on a standard
glass fiber filter (typically 0.45 um nominal size) after drying at 105 degrees C. Volatile
suspended solids reflects the weight of organic matter in the dried solids that burns off after
combustion at 550 degrees C and indicates the organic solids content of the water sample.
Non-volatile suspended solids reflects the weight of solids remaining on the filter after
combustion and indicates the inorganic solids (primarily sediment) content of the water sample.
The sum of volatile and non-volatile suspended solids is the total suspended solids content.
Over the seven-year study period (Jones, 1996), summer surface waters averaged 22.7 ppm total
suspended solids (Figure 8) with a high of 58.4 ppm in 1990 and a low of 7.8 ppm in 1991.
Volatile suspended solids averaged 4.7 ppm with a high of 9.0 ppm in 1993 and a low of 2.8 ppm
in 1995. Non-volatile suspended solids averaged 18.0 ppm with a high of 52.0 ppm in 1990 and a
low of 4.6 ppm in 1991.
The previously mentioned nutrient and organic matter sources (refer to Nutrients Section, pp.
12-13) contribute to the volatile solids concentration. Sediment (refer to Soil Erosion and
Sedimentation section, pp. 9-10) also contributes to the nonvolatile solids concentration. For
information on nutrient and sediment regulations, see Appendix B, Nutrient and Sediment
Regulations.
Pathogens
Cryptosporidium and Giardia are two pathogenic microorganisms that are found in the intestines
of livestock and wild animals. Both cause intestinal disorders in humans and both are resistant
to conventional water treatment methods. Although Cryptosporidium outbreaks in the U.S. have
been relatively rare until the last decade, several outbreaks have occurred since 1983 that have
caused a number of deaths. Giardia outbreaks are more common but much less likely to cause
death. Most outbreaks of these pathogens have been linked to runoff from feedlots, manure piles,
and fields where liquid waste was land-applied. The presence of livestock in the Higginsville
City Lake Watershed makes pathogens a valid concern. Efforts to exclude livestock from
watercourses and reduce movement of animal wastes in runoff will reduce the presence of these
pathogenic organisms reducing the risk of an infectious outbreak.
Trihalomethanes
Trihalomethanes (THM's) are chemical byproducts formed when chlorine is used to disinfect
drinking water. THM's have been linked to rectal, bladder, and pancreatic cancers in humans.
THM's form as chlorine reacts with organic matter in the water being treated. The current MCL
for THM's is 100 ppb. Under an EPA rule, proposed in 1995, the MCL will be lowered to 80 ppb.
THM concentrations in the Higginsville Public Water Supply system (Figure 9) show considerable
seasonal variation with the lowest values in winter and the highest values in spring and summer.
High THM concentrations correspond with seasonal algal bloom which raise the level of organic
matter in Higginsville City Lake. THM concentrations can be reduced by reducing the levels of
organic matter in the water being treated. Reducing nutrient and animal waste loading will
reduce levels of organic compounds.
Toxic and Hazardous Materials
The Lafayette County Emergency Management Plan is being revised at this time. The revision is
scheduled for completion by October 1, 1996 (Florence, 1996).
Evidence of illegal dumping was observed at several locations in the watershed. Although
difficult to control, such dumping can be a source of contaminants to the water supply.
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