Lake Olathe Watershed of Olathe, KS

Liz Coffey

Spring 2010

Hydrologic Setting / Hydrologic & Geologic Properties
Water Resources / Groundwater Quality & Contamination
Conclusions / References

Hydrologic Setting

The Lake Olathe watershed extends over 43 km2 (10,800 acres) of land that encompasses the drainage areas of Lake Olathe, Cedar Lake, and Cedar Creek. (Fig.2) Cedar Creek is the main tributary that links the two lakes together. Surface area of Lake Olathe covers 0.68 km2 (170 acres) and Cedar Lake covers about 0.21 km2 (54 acres). The surface waters are used for recreation purposes and a drinking water source for many residents. Land use of the area is about eighty-three percent used as agricultural cropland and grassland. (Mau, 2004) The Lake Olathe watershed is overlying the Western Interior Plains Aquifer System that extends through Kansas, Missouri, and Nebraska as seen in Figure 1.

Figure 1. Extent of the Western Interior Plains aquifer system shown in purple. (USGS, 1997)

The range of precipitation averages for the area is 3.0 cm (1.2 in) to 13.3 cm (5.24 in) for a maximum in the month of June. (HPRCC, 2009) The average precipitation of the area is 101.6 cm (40 in) that occurs primarily during the growing season between April and October. Average temperature for the year is 22.2 C (55 F) with an average temperature of January as -3.8 C (29 F) and July as 46.2 C (79 F). (Mau, 2004)

Figure 2. Location of Lake Olathe watershed, land use in the watershed, and real-time water quality monitors. (USGS, 2004)

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Hydrologic & Geologic Properties

The Lake Olathe watershed is underlain by sedimentary bedrock deposited during late Pennsylvanian time (about 285 to 320 million years ago). The bedrock is mostly shale, with some prominent limestone layers and sandstone. Pre-Illinoian glacial till and a thin layer of loess (windblown Pleistocene deposits) cover the bedrock. Soils in the watershed were formed from windblown loess, glacial outwash, and residuals derived from the weathering of shale and limestone bedrock (Mau, 2004).

Recharge to the aquifer involved is seasonal due to the variability of the precipitation to the area. Ground water moves downward through permeable rocks due to gravity and moves east from the southeast laterally. The yield is generally less than 50 gpm for the wells in Olathe, KS. (O’Conner, 1971) The structure and character of the rocks may affect the direction and rate of movement of the water. Ground water may discharge into the three water bodies of the watershed or may evaporate or transpire by plants. Some of the groundwater is discharged from wells by those not close enough the water lines from the two lakes but is very minimal. Over a long period of time, equilibrium generally exists between the recharge and discharge. (O’Conner, 1971) Ground water of the Western Interior Plains Aquifer System has an average of concentrations of 1,000 mg/L of total dissolved solids with a maximum of 200,000 mg/L concentration. Water from this aquifer system is not generally pumped due to its highly mineralized nature and its deep burial of about 76 m.(250 ft.). Although it is deeply buried, the aquifer thickness ranges from 457 m. (1,500 ft.) to 305 m.(1,000 ft.) (USGS, 1997)

Figure 3. Map shows aquifer thickness of the extent of the Western Interior Plains aquifer system in feet. The circle shows the general location of Johnson County, KS. (USGS, 1997)

Physical Characteristics of Cedar Lake and Lake Olathe.

[--, not applicable]

Characteristic (unit of measurement) / Cedar Lake / Lake Olathe
Total storage volume at dam crest elevation (cubic meter), 2000 / 4.1E5 (334 acre-foot) / 3.8E6 (3,100 acre-foot)
Surface area (square kilometers) / 0.22 (54 acres) / 0.69 (170 acres)
Mean depth (meters) / 1.9 (6.20 ft.) / 5.5 (18.2 ft.)
Maximum depth (meters) / 4.3 (14.0 ft.) / 13.4 (44.0 ft.)
Mean annual inflow (cubic meters per second) / -- / 0.44 (15.6 c.f.s)
Drainage area of watershed (square kilometers) / 15.8 (6.10 sq.mi.) / 28 (10.8 sq.mi.)

(Table taken from Mau, 2004)

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Water Resources

Water from the Lake Olathe watershed is used extensively for drinking water and recreation. There are approximately 1,500 residents in the watershed that live mostly in single-family homes and farms with the city of Olathe nearby with a population well over 100,000 residents. The watershed area is experiencing rapid development and urbanization. Guidelines have been set for development in the Lake Olathe watershed by the City of Olathe. These guidelines are based on Best Management Practices propagated by the Mid America Regional Council and the American Public Works Association. (City of Olathe, 2010)

After some concern was raised with Lake Olathe and Cedar Lake’s bottom sediments and their chemical properties, samples were taken from both locations. To precede the sampling bottom sediment mapping was conducted in July 2000 for Cedar Lake and Lake Olathe. The sampling provided information that was used to help describe the effects of industrial, agricultural, residential activities in the watershed. After analysis, it was found that there were large mean concentrations of phosphorous and a few trace elements were present in the lake bottoms. A study done in 2005 concluded that there were also elevated concentrations of manganese in both lakes but an emphasis was made on Lake Olathe because its use as drinking water. High concentrations of phosphorous could lead to eutrophication (nutrient enrichment) that degrades water quality. An eutrophication condition in the lakes would provide a food source for phytoplankton (algae) that may cause seasonal algal blooms.

Figure 4. Real-time water quality and chemical analysis monitor used in Cedar Lake and Lake Olathe. (Mau, 2004)

Figure 5. (Left) Technician working on the intake structure set up in Lake Olathe. (Right) Schematic view of intake tower. (Rasmussen, 2005)

Seasonal algal blooms can also endanger some aquatic species and could also be the cause of the taste-and-odor issues that will be discussed later. They can be caused by excessive nutrient concentrations, favorable sun and temperature conditions, and presence of pesticides. Data collected from intake structures (Fig.5) is used for real-time data for water quality. Six trace elements that were found in the soil samples included arsenic, chromium, copper, lead, nickel, and zinc and all exceeded the soil-quality guidelines created by the Environmental Protection Agency for some sensitive aquatic species. Higher concentrations of these trace elements could be more deposited from sediment transport and accumulation than industrial, agricultural, residential activities in the watershed. Analysis is still underway and has not found any definitive results on the origin of the excess phosphorous. Although the source is not defined, it was concluded that the excess phosphorous had been transported in some way to Cedar Lake and Lake Olathe. Predictions of the seasonal algal blooms will be the done by monitoring water quality with real-time data using a probe shown in Figure 4. This notification system will be added to the watershed water quality protection plan.

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Surface Water Quality & Contamination

Every year there is a problem with a taste-and-odor water quality in the Olathe community. In 2000, a study done in cooperation with the City of Olathe, Kansas Department of Health and Environment, and United States Geological Survey to determine the water quality of Lake Olathe and the connecting streams. (Mau, 2000 and Mau, 2002) The goal of the study was to better understand the concentration of chemicals in stream and lake water, the conditions and processes in the lake watershed, which led to the algal growth and taste-and-odor problems in the drinking water from Lake Olathe. The concluding action of this investigation was to create a comprehensive watershed protection plan to be used for the community for maintaining and protecting the water quality in Lake Olathe.

Ground water quality is well measured in the wells in Olathe, KS. Figure 6 indicates that at 76 m(150 ft.) in the Douglas, Lansing, and Kansas City Groups the water is moderately saline at that depth. As mentioned previously, the dissolved solids concentrations of the area of concern is very high.

Figure 6. Table of the stratigraphic unit and the water quality and well yield that it is associated with. Lake Olathe watershed is associated with the top unit of this table. (O’Conner, 1971)

Regulatory agencies that are responsible for the protection or cleanup of contaminated waters in the Lake Olathe Watershed include the United States Environmental Protection Agency (EPA) Region 7, Kansas Department of Health and Environment (KDHE) Bureau of Water, and the City of Olathe.

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Conclusions

The surface water of the Lake Olathe watershed is one of the prominent water sources for both recreation and consumption. It provides water for agriculture and human use and consumption. High concentrations of phosphorous and manganese are areas of concern and of current research. Algal blooms are the cause of the problems of taste-and-odor drinking water in the area. The City of Olathe is working in cooperation with federal agencies to create a watershed protection plan.

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References

City of Olathe, 2010. Development in the Lake Olathe Watershed. http://www.olatheks.org/OMS/LakeOlatheWatershed [retrieved on 29, April 2010].

High Plains Regional Climate Center (HPRCC). 2009. Olathe 3 E, Kansas. http://www.hprcc.unl.edu/cgi-bin/cli_perl_lib/cliMAIN.pl?ks5972 [retrieved on 29, April 2010].

O’Connor, H. 1971. Geology and Groundwater Resources of Johnson County, Northeastern Kansas State Geological Survey, The University of Kansas, Bulletin 203. http://www.kgs.ku.edu/General/Geology/Johnson/ [retrieved on 4, May 2010].

Mau, D.P. 2000. Sediment Deposition and Selected Water-Quality Characteristics in Cedar Lake and Lake Olathe, Northeast Kansas, 2000. Prepared for USGS with City of Olathe and KDHE. http://ks.water.usgs.gov/pubs/reports/wrir.02-4073.html [retrieved on 12, April 2010]

Mau, D.P. and C.S. Adams. 2002. The Lake Olathe Watershed – Understanding an Important Resource. Prepared for USGS from City of Olathe. http://ks.water.usgs.gov/pubs/fact-sheets/fs.057-02.html [retrieved on 12, April 2010].

Mau, D.P., A.C. Ziegler, S.D. Porter, and L.M. Pope. 2004. Surface-Water-Quality Conditions and Relation to Taste-and-Odor Occurrences in the Lake Olathe Watershed, Northeast Kansas, 2000−02. Prepared for USGS. http://pubs.usgs.gov/sir/2004/5047/ [retrieved on 11, April 2010]

Rasmussen, P.P. and D.H. McAllister. 2005. Monitoring the Water Quality of Lake Olathe, Johnson County, Kansas. Prepared for USGS from City of Olathe. http://pubs.usgs.gov/fs/2005/3093/ [retrieved on 15, April 2010].

USGS. 2009. Water-Quality Study of the Lake Olathe Watershed, Northeast Kansas. http://ks.water.usgs.gov/studies/qw/olathe/ [retrieved on 11, April 2010].

USGS. 1997. Ground Water Atlas of the United States Kansas, Missouri, and Nebraska HA 730-D. Prepared by USGS. http://pubs.usgs.gov/ha/ha730/ch_d/D-text7.html [retrieved on 4, May 2010].

This webpage was designed for Introduction to Hydrogeology
Instructor: Dr. Marcia K. Schulmeister of Emporia State University
For questions or comments contact Liz Coffey
Created on April 30, 2010