USGS Hydrologic Data and Studies in Support of the State of Kansas Total Maximum Daily Load (TMDL) Program

Introduction

The State of Kansas is required by the Federal Clean Water Act of 1972 to develop a total maximum daily load (TMDL) for impaired waters in the State. A TMDL is an estimate of the maximum pollutant load (material transported during a specified time period) from point and nonpoint sources that a receiving water can accept without exceeding water-quality standards. The USGS is providing hydrologic data-collection and studies support to the Kansas Department of Health and Environment (KDHE), the agency tasked with implementing the TMDL process in Kansas. The specific USGS activities described below include the estimation of potential runoff-contributing areas, estimation of streamflow-duration curves at ungaged sites, and real-time water-quality monitoring. These activities are supported in part by the Kansas State Water Plan Fund.

Detailed information about the TMDL process in Kansas is provided on the KDHE TMDL website.

Keynote speech presented by Robert Hirsch, Associate Director of Water for the USGS, at the TMDL Conference in St. Louis, Missouri, March 5, 2001. USGS Technical Assistance for TMDLs .

 

Point-source pollution

Nonpoint-source pollution

REAL-TIME WATER-QUALITY MONITORING

The USGS is developing a real-time water-quality network in Kansas that will provide real-time load estimates for use in determining TMDL's. Specific objectives of the network are to: (1) develop relations between water-quality parameters that can be measured onsite in real time (water temperature, specific conductance, pH, dissolved oxygen, and turbidity) and used as surrogates for water-quality constituents of concern to KDHE, the U.S. Environmental Protection Agency, and others, such as chloride, sulfate, bacteria, suspended sediment, and atrazine; (2) enhance the existing stream-gaging network with real-time water-quality monitors to provide an alert network for optimizing the frequency of water-quality sample collection and warning water suppliers so that treatment can be more efficient; (3) develop a relation between fecal coliform and Escherichia coli (E. coli) as a future water-quality standard replacement for fecal coliform bacteria; and (4) determine cumulative mass load of major ions, dissolved solids, nutrients, suspended sediment, and bacteria.

Real-time water-quality probe.

For related publications and other information visit our Real-Time Water Quality web page

For additional information, please write or call:

Teresa Rasmussen
U.S. Geological Survey
4821 Quail Crest Place
Lawrence, Kansas 66049-3839
Telephone: (785) 832-3576
Fax: (785) 832-3500
Email: rasmuss@usgs.gov

POTENTIAL RUNOFF-CONTRIBUTING AREAS

Development of TMDL's requires an understanding of potential source areas of storm runoff that are the most likely contributors of nonpoint-source pollution within a basin. Using available soil, topographic, and land-use digital data, the USGS is estimating potential runoff-contributing areas statewide. Results of these analyses will compare runoff potential both between and within individual stream basins. Also, such information will provide guidance for the targeting of best-management practices to reduce runoff and meet TMDL requirements.

The study is proceeding in three phases. In phase one, the U.S. Department of Agriculture's 1:250,000-scale State soils geographic data base (STATSGO) and the USGS 1-km-resolution digital elevation model (DEM) were used to estimate potential runoff-contributing areas in the Kansas-Lower Republican River Basin. In phase two, the same digital data sets were used to estimate potential runoff-contributing areas statewide. The first two phases were intended to provide a means of comparing runoff potential between basins. In phase three, the U.S. Department of Agriculture's 1:24,000-scale soil survey geographic data base (SSURGO), the USGS 100-m-resolution DEM, as well as digital land-use data from the Kansas Applied Remote Sensing Program, University of Kansas, will be used to estimate potential runoff-contributing areas statewide. The use of more spatially detailed data in phase three will enable a comparison of runoff potential between areas within individual basins.

For additional information, please write or call:

Kyle Juracek
U.S. Geological Survey
4821 Quail Crest Place
Lawrence, Kansas 66049-3839
Telephone: (785) 832-3527
Fax: (785) 832-3500
Email: kjuracek@usgs.gov

STREAMFLOW-DURATION CURVES

The KDHE approach to TMDL Curve Methodology is based on the dynamic state of loads. Because loads vary directly with streamflow as well as pollutant concentration, KDHE has devised a plan to relate TMDL constituent criteria to streamflow duration. This approach yields the actual design load along with an estimate of the duration, or percentage of time the load can be expected in any given year.

KDHE develops the TMDL curves for sites with USGS continuous-record stream-gaging sites. For sites without USGS continuous-record stream-gaging stations that require TMDL curves, the USGS is estimating the streamflow-duration curve. The method for estimating streamflow duration for ungaged sites relies on regionalized streamflow characteristics to generate five different duration-curve points and the average regionalized slope of the curve. Several medium- to low-flow measurements are made concurrently with nearby, long-term USGS stream-gaging stations for verification or adjustment of the estimated duration curve. The figure below shows a test of the estimation method at a long-term continuous-record stream-gaging site:

For additional information, please write or call:

Seth Studley
U.S. Geological Survey
4821 Quail Crest Place
Lawrence, Kansas 66049-3839
Telephone: (785) 832-3541
Fax: (785) 832-3500
Email: sstudley@usgs.gov