Research Methodology and Data

The National Center for Water Quality Research (NCWQR) has been collecting and testing surface water samples from streams and lakes since 1969. Much of our work has involved studies of the effects of agricultural and urban land use practices on water quality.  Our “signature” program is the Heidelberg Tributary Loading Program (HTLP). This program currently includes sample collections at 18 stations, located at or near U.S. Geological Survey (USGS) streamflow monitoring stations.  Samples are analyzed at the NCWQR laboratories for nutrients and suspended sediments.  The nutrient and sediment concentration data provided by the NCWQR, combined with the streamflow data provided by the USGS, support calculations of the tons of nutrients and sediments that move past each station each day.  Two of our stations in the Sandusky Watershed now have 40 years daily data.  More than 50% of Ohio’s land area lies “upstream” from HTLP sampling stations.   

In addition to the HTLP, the lab operates a private well testing program that provides information to homeowners of the concentrations of nutrients, selected pesticides and metals in their drinking water.  The biological branch of the NCWQR has assessed habitat quality and biological diversity in nearshore areas of Lake Erie as well as wetlands, primary headwater streams and agricultural drainage ditches. 

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View of Gillmor Science Hall at Heidelberg University where the NCWQR is located

Tributary Loading Program Background

In 1974, the Water Quality Laboratory initiated a program of detailed sample collection and analyses for a set of Lake Erie tributaries as part of the U.S. Army Corps of Engineers’ Lake Erie Wastewater Management Study. The objective of the study was to determine the total quantities (loads) of nutrients and suspended sediments moving from watersheds through major tributaries and into Lake Erie. At the request of the Ohio Farm Bureau Federation, that program has expanded to include rivers that drain into the Ohio River Basin. The HTLP now represents the most detailed and long-term program of its type in the United States and serves multiple roles in nonpoint pollution research, education, modeling, and adaptive management.  In 1980 a pesticide monitoring program was “piggybacked” on the nutrient and sediment program for a subset of rivers and the HTLP continues to provide on pesticide export from agricultural watersheds as well as nutrient and sediment export.

Lab photos stations

A map showing each of the monitoring stations, except for Old Woman Creek. The photos show the Sandusky River (top), Portage River (middle), and Maumee River (bottom) sampling stations

Tributary Sampling

At 16 of the 18 stations, submersible pumps located in the rivers continuously pump stream water into sampling wells located in buildings at each station.  Refrigerated automatic samples pump water from the sampling wells into sample bottles at eight hour intervals (4:00 AM, 12:00 noon, and 8:00 PM) each day, providing 21 separate samples each week.  On Mondays, sampler bases are exchanged with filled bottles returned to the laboratory for analysis and a new set of bottles placed in the automatic sampler for the following week.  During periods of high flow and high turbidity all three samples for a given day are analyzed for nutrients and suspended sediments.  During low flow periods, only a single sample per day is analyzed.  More than 140,000 samples have been analyzed as part of this program and the resulting concentration data are available on the NCWQR website

Lab photos people

Retrieving samples from the stations (top) and laboratory analysis (bottom)

Focus on Dissolved Reactive Phosphorus

The NCWQR’s tributary loading program has documented large increases in the movement of dissolved reactive phosphorus (DRP) from Northwestern Ohio cropland through streams and rivers into Lake Erie. These increases began in the mid-1990s and coincide with increasing problems of excessive algal growth in the Western Basin of Lake Erie. The deliberations of the Ohio Lake Erie Phosphorus Task Force concluded that these increases in DRP loading to Lake Erie were contributing to the algal problems and that programs to reduce DRP loading should be developed.

While the NCWQR research programs have largely focused on studies of the transport of phosphorus and other nutrients, sediments and pesticides at a set of river monitoring stations throughout Ohio, in recent years our studies have extended onto cropland itself to help determine the causes of the increased DRP runoff. Our cropland and soils studies include measurements of phosphorus stratification in area soils (see below) and relationships between soil testing methods and water testing methods. We have assembled a BMP “toolbox” to help guide farmers and their advisors in reducing DRP export from cropland. Our recent research has also extended out into Maumee Bay and the Western Basin of Lake Erie to help quantify linkages between agricultural nutrients that move into the lake during storm events and subsequent excessive algal growth in the Lake. Learn more about Heidelberg University’s work on dissolved reactive phosphorus.

Phosphorus Stratification Study

In a separate study, NCWQR staff and research partners analyzed a total of 4,270 soil samples, creating one of the largest soil data sets available on the topic of phosphorus stratification.

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