Urban Water Quality Monitoring in Johnson County Kansas

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Johnson County, a suburban part of the Kansas City metropolitan area, is one of the most populated counties in Kansas with 544,000 people in 2010, a 21 percent increase in population since 2000, according to the U.S. Census Bureau. Located in northeastern Kansas, about one-half of the county is urban. Urban, industrial, and agricultural land uses affect the quality of streams and lakes in the county. Water-quality impairments related to excessive nutrients, sediment, and bacteria have been identified by the Kansas Department of Health and Environment. Since 2002, the USGS has conducted several past and ongoing studies related to hydrology and stream quality. Analysis of the data obtained from these studies is being used to better understand streamflow characteristics such as flooding and urban hydrology and factors that affect water quality and ecosystem health. In addition, these studies identify current and changing conditions and help municipalities address regulatory requirements related to the Clean Water Act.

Streams in Johnson County in northeast Kansas are important for human and environmental health, water supply, recreation, and aesthetic value. Rapid population growth and urbanization in Johnson County has affected stream quality. Urbanization results in more residential, commercial, and industrial developments, and generally affects streams by altering hydrology, geomorphology, chemistry, and biology. These changes affect aquatic communities. Contamination entering streams in rural and urban areas can originate from point sources (such as wastewater treatment discharges) and nonpoint sources (such as stormwater runoff, leaking sewer lines, septic tanks, and atmospheric deposition).

Results from these studies are used to define current water-quality conditions, understand variability in conditions, evaluate effects of urbanization, develop effective water-quality management plans, document changes in water quality, and evaluate conditions relative to total maximum daily loads (TMDLs), National Pollutant Discharge Elimination System (NPDES) requirements, and water-quality standards.

Monitoring Water Quality to Assess Total Maximum Daily Loads (TMDLs)

Total maximum daily loads (TMDLs) are water-quality criteria that originate from national recommended criteria (US EPA) and state water-quality standards (Kansas Department of Health and Environment). In Johnson County, most water-quality impairment is caused by excessive nutrients, sediment, and fecal bacteria. This project monitors water-quality constituents in stormwater that are regulated by TMDLs in Johnson County streams and lakes and evaluates the utility of the monitoring data in assessing water-quality improvements. Water-quality samples are being collected at 26 sites and analyzed for nutrients (nitrogen and phosphorus), sediment, and E.coli bacteria.

Assessment of Streamflow Alteration in Johnson County Streams

Alteration of the natural streamflow regime, or hydromodification, is a primary factor affecting stream health in urban areas and is potentially a major cause of ecological stream impairments. This study will quantify hydromodification in selected watersheds, identify streamflow metrics that may have important implications for stream quality, and develop tools for monitoring streamflow changes that may be used to evaluate management practices that affect streamflow.

Effects of Wastewater Discharge and Treatment Facility Upgrades on Stream Quality

The effects of wastewater effluent discharge on stream quality were assessed in Indian Creek and in the Blue River during 2008-2014. Physical and chemical conditions were evaluated using previously and newly collected discrete and continuous data. Conditions were compared with an assessment of biological community composition and ecosystem function along the upstream-downstream gradient to understand the potential effects of wastewater effluent on water quality, biological community structure, and ecosystem function.

Evaluation of Water Quality of Johnson County Streams

Water quality of Johnson County streams was evaluated during 2002-2010 to describe water quality in streams throughout Johnson County; identify contaminant source areas; assess biological conditions in relation to environmental variables; evaluate the effects of urbanization; and estimate water-quality constituent concentrations, loads, and yields.

Types of data collected for evaluation included streamflow, water chemistry (discrete and continuous data), streambed sediment chemistry, benthic macroinvertebrates, periphyton (algae), habitat measurements, and land-use information. Constituents analyzed in water and sediment were suspended sediment, dissolved solids and major ions, nutrients (nitrogen and phosphorus), indicator bacteria (E.coli), pesticides, and organic wastewater and pharmaceutical compounds. This information is used to define current water-quality conditions, document changes in water quality, and evaluate effects of urbanization.

Sediment Transport to Streams and Lakes in Johnson County

Sediment transport was studied during 2006-2008 to better understand the effects of urbanization, construction activity, management practices, and impoundments on suspended-sediment concentrations and loads in Johnson County streams and lakes. This information is used to better understand where and at what scale impacts from landscape disturbance can be controlled to protect stream water quality and stream ecosystems.

Monitoring Water Quality to Assess Total Maximum Daily Loads (TMDLs)

This project is currently underway and results will be available in 2019.

Assessment of Streamflow Alteration in Johnson County Streams

This project is currently underway and results will be available in 2019.

Effects of Wastewater Discharge and Treatment Facility Upgrades On Stream Water Quality

After changes in treatment practices at the Middle Basin Wastewater Treatment Plant (WWTP), which discharges into Indian Creek, nutrient loads decreased by 40-55 percent. Wastewater effluent had a substantial effect on nutrient concentrations in Indian Creek. Other urban sources of pollutants also caused changes in Indian Creek stream quality. Urban influences likely affect the structure of macroinvertebrate communities in Indian Creek. Multiple urban influences, rather than wastewater effluent discharges alone, likely affect biological conditions, particularly macroinvertebrate communities in Indian Creek. Further study of wastewater effluent transport indicated that nutrient concentrations decreased on a downstream gradient at greater rate than can be explained by dilution alone, indicating that other factors, such as biological activity, could be playing a role in reducing nutrient concentrations. Year-round sediment oxygen demand was highest in Indian Creek compared to other streams where sediment oxygen demand was measured in eastern Kansas, likely a result of the wastewater influence.

After upgrades to the Blue River Main WWTP, nutrient concentrations in the upper Blue River downstream from the WWTP decreased by 30-50 percent. Despite decreases in nutrient concentrations, nutrient concentrations in the upper Blue River were still 4 to 15 times larger downstream from the WWTP than upstream during below-normal and normal streamflows (about 75% of the time). Abundance of aquatic organisms tolerant of degraded water-quality conditions increased downstream from the Blue River Main WWTP. An evaluation of stream metabolism indicated that effects of wastewater discharge in the upper Blue River did not cause persistent declines in overall stream health.

Evaluation of Water Quality of Johnson County Streams

Stream quality was characterized on the basis of watershed land use, streamflow, water and streambed-sediment chemistry, riparian habitat conditions, algal periphyton communities, and macroinvertebrate communities. Biological conditions reflected a gradient in urban land use, with the less disturbed streams located in rural areas of Johnson County. The environmental variables, percent impervious surface and percent urban land use, were consistently highly negatively correlated with biological conditions.

Policies and management practices that may be most important in protecting the health of streams in Johnson County are those that minimize the effects of impervious surfaces; protect stream corridors; and decrease the loads of sediment, nutrients, and toxic chemicals that directly enter streams through stormwater runoff and discharges.

Sediment Transport to Streams and Lakes in Johnson County

The largest amount of sediment (per unit area) transported in Johnson County streams was observed downstream from increased construction activity. Sediment (per unit area) transported downstream from the largest active construction site was 5 to 55 times larger than at other sites. Among sites in the Mill Creek basin, sediment (per unit area) transported from urbanizing areas was about 2 to 3 times larger than from older, more stable urban or rural basins. However, among larger basins, Indian Creek, the oldest urban basin, transported 2 to 10 times more sediment (per unit area) than urbanizing or rural basins.