The upper White River Basin drains about 2,718 square miles of central and east-central Indiana. It takes in all or part of 16 counties, including some of the state's most populous cities — Indianapolis, Fishers, Muncie and Anderson — along with more than 2,180 miles of streams and four water-supply reservoirs. Per unit of area, the region is a major source of nitrogen and phosphorus, so water managers and conservation groups watch its water quality closely. This page summarizes a U.S. Geological Survey fact sheet prepared with The Nature Conservancy.
The upper White River Basin and the three study streamgages. USGS figure.
The land
As of 2019, agriculture covered about 55.6% of the basin, developed land 29.5% and forest 13.3%. Moving downstream, farmland shrinks as a share of the land and development grows.
What was measured
The USGS and The Nature Conservancy had earlier studied changes in the concentrations and fluxes (amounts carried per unit of time) of three nutrients — total phosphorus, nitrate plus nitrite, and total Kjeldahl nitrogen — and total suspended solids (sediment) at three gages on the White River: at Muncie, near Nora and near Centerton. An updated 2023 study added 3 more years of data, used newer methods, and looked at human factors that might be driving change, covering water years 1997 to 2019.
Separating trends from weather
Nutrient loads rise and fall with streamflow: at Centerton, yearly nitrate-plus-nitrite flux tracked annual mean streamflow closely (correlation 0.725). The method used, Weighted Regressions on Time, Discharge and Season (WRTDS), "flow-normalizes" the data to strip out that year-to-year noise so that changes caused by other factors, such as land use, stand out.
*Figure 2.Plot of annual fluxes of nitrate plus nitrite estimated by Koltun (2023) and annual mean streamflows at the White River near Centerton, Indiana (U.S. Geological
Survey streamgage 03354000; U.S. Geological Survey, 2022).*
But streamflow itself has been changing. At the Nora gage, annual mean flows have risen since about the mid-1970s — not because of dams or diversions but, likely, because precipitation has increased, as records at Indianapolis International Airport show. The 2023 study used generalized flow normalization, which accounts for some of this long-term shift.
Annual mean streamflow at the White River near Nora and annual precipitation at Indianapolis International Airport, with smoothed trend lines. USGS figure.
Direction of change, 1997–2019
| Gage | Clear declines (statistically significant) | Other results |
|---|---|---|
| Muncie | concentrations of sediment and nitrate plus nitrite | no significant change in fluxes |
| Nora | concentrations of sediment, phosphorus and Kjeldahl nitrogen; fluxes of nitrate plus nitrite and Kjeldahl nitrogen | other changes not significant |
| Centerton | concentrations and fluxes of nitrate plus nitrite and Kjeldahl nitrogen | phosphorus concentration rose significantly; the sediment result is uncertain because of a large gap in the record |
Why is it hard to find the cause?
Many interrelated changes happened at once:
- Farmland to development. Between the Nora and Centerton gages, the shares of land in cultivated crops and pasture/hay fell by 3.49 and 1.18 percent from 2001 to 2019, while low-, medium- and high-intensity development rose by 1.18, 2.67 and 1.15 percent.
- Population. From 2000 to 2020 the Indianapolis metro area grew rapidly while Anderson and the Muncie metro area shrank slightly; together the three areas gained more than 445,000 people.
- Fertilizer. In 12 of the 16 counties, nitrogen and phosphorus applied as manure fell from 1987 to 2017, while the much smaller amount of nitrogen from commercial fertilizer used in non-farm settings rose — possibly tied to farmland becoming developed land.
- Wastewater. Even if a growing population uses less fertilizer overall, it can add nutrients through more treated wastewater, and those loads shift as treatment changes.
Conclusion
Better analytical methods now make it easier to account for variable and changing streamflow, but identifying what drives changes in nutrient and sediment levels remains hard when several factors interact. The authors call for more water-quality and streamflow monitoring, over time and across more places, and for more frequent, accurate and detailed data on the factors that affect nutrient and sediment transport.
Sources
- U.S. Geological Survey: "Potential drivers of change in fluxes of nutrients and total suspended solids in the upper White River Basin, Indiana," Fact Sheet 2023–3009, prepared in cooperation with The Nature Conservancy.
- Main study summarized: Koltun (2023); earlier study: Koltun (2019). Other works cited include Hirsch and others (2015), Hirsch and DeCicco (2015) and Choquette and others (2019), on WRTDS methods. Pictures an earlier version of this page left out were restored on 2026-09-26.
Licence: CC0 1.0 (public domain) · Adapted from pubs.er.usgs.gov
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