Indiana's White River, 1992–96: Farm Chemicals, Nitrate and City Runoff

The White River near Martinsville, Indiana. Photograph: Charles Crawford, U.S. Geological Survey.

The White River drains much of central and southern Indiana, from farmland in the north through Indianapolis, Muncie and Anderson to the steep, wooded hills of the south-central basin. From 1992 to 1996 the U.S. Geological Survey studied its water as one of the river basins in its National Water-Quality Assessment (NAWQA) Program, which Congress funded from 1991 to track the country's water problems, how they change and why. This is what the study found.

The basin

In 1990 about 2.1 million people lived in the basin, some three-quarters of them in the north. About 70% of the land is farmed, and in 1992 corn and soybeans covered 78% of the cropland. Herbicides go onto virtually all of the corn and soybean crop at spring planting, so the basin's water story is largely a farm story, with the cities adding their own.

Farmland (yellow), forest (green) and cities (red) across the basin, with the study’s sampling sites. U.S. Geological Survey.

Pesticides in the streams

Pesticides turned up in streams all over the basin, at urban and farm sites among the highest in the nation. Near the mouth of the White River, 25 pesticides or their breakdown products appeared in at least 5% of samples; atrazine and metolachlor were always found, cyanazine and alachlor often.

• When. Concentrations peak between May and July, when rain washes freshly applied chemicals off the fields; from 1994 through 1996, 69 to 90% of the year's load of the five most-used farm pesticides entered the river in those months. For about 6 weeks each spring, atrazine near the mouth ran above its drinking-water limit of 3 μg/L, although its annual average, the measure the standard is based on, never did. Water near the mouth is not drunk, but Indianapolis, Seymour and Bedford draw some of their supply from the White or East Fork White Rivers upstream.
• How much is used. Streams generally carry more of the chemicals farmers use most. In 1993, southern Indiana used about four times as much of the corn herbicide butylate as central Indiana, and its streams carried far more.
• New products show up fast. The corn herbicide acetochlor, registered in 1994, reached about 2 μg/L in the White River within two years, as its forerunner alachlor declined.
• Land use. The lawn and garden insecticide diazinon was in almost every sample from Little Buck Creek, whose watershed is 57% urban, and in none from Kessinger Ditch, which is 94% farmland.

Use explains only part of the picture: each pesticide’s chemistry decides how much of it reaches the river. U.S. Geological Survey.

Drainage matters too. Much of the upper Midwest's poorly drained farmland is laid with tile drains, buried pipes that carry water from the soil straight to the nearest ditch. In spring they flush newly applied atrazine into streams such as Sugar Creek, short-circuiting the slow path through the ground.

Groundwater was far cleaner. Of 94 shallow monitoring wells, 14 pesticides were detected, only six more than once, all at less than 0.2 μg/L; none came close to a drinking-water limit, and the highest atrazine level was under a twentieth of its standard.

Drains and runoff carry farm chemicals into the basin’s streams. Photographs: Jeffrey Martin and Nancy Baker, U.S. Geological Survey.

Nitrate

Most of the basin's nitrogen comes from commercial fertilizer, about nine-tenths of it put on corn; point sources such as sewage plants and factories supply only about 3%. Typical nitrate levels in the streams, 2 to 6 mg/L, were higher than at most NAWQA sites in the country, though samples rarely broke the drinking-water limit of 10 mg/L. Streams run highest in nitrate from autumn to late spring, when plants are not using it and rain flushes it from wet soil, and they carry more where soils drain well. Clifty Creek ran higher than its soils would predict, probably because of the manure from the many farm animals in its counties.

Where the basin’s nitrogen comes from: fertilizer 61%, manure 19%, the air 17%, sewage and industry 3%. U.S. Geological Survey.

Underground, the answer depends on the rock. Sand and gravel aquifers open to the surface under row crops are the most exposed: water soaks through them fast, carrying nitrate past plant roots, and 17% of shallow wells in them exceeded the 10 mg/L limit. Deeper in the same aquifers, 25 to 50 feet below the water table, there was little or none. Aquifers sealed under clay, which underlie more than half the basin and supply many rural household wells, were well protected: about 65% of their shallow wells had no detectable nitrate at all.

Nitrate in shallow wells: clay-sealed (confined) aquifers against open (surficial) ones. U.S. Geological Survey.

The cities

Urban areas add their own mix. Volatile organic compounds, chloroform most often, were found in more than half of shallow urban monitoring wells, against 6% under farmland, though none exceeded a drinking-water standard, and most drinking-water wells are deeper. Downstream of Muncie, Anderson and Indianapolis, phosphorus and ammonia rose, probably from treated sewage and runoff. Lead, plastics compounds and long-banned chemicals such as chlordane, dieldrin and PCBs linger in streambed sediment near Indianapolis and build up in animals such as freshwater clams. Fish-consumption advisories for PCBs and mercury cover parts of the basin.

The worst urban problem was the overflows. Sewers that carry both sewage and rainwater overflow in storms, and that overflow and the stormwater running off the streets strip oxygen from the river. One such event at Indianapolis in 1994 killed 510,000 fish.

Stormwater and sewer overflows remain a problem for the basin’s streams. Photograph: Charles Crawford, U.S. Geological Survey.

A river that has come back

In 1909 two men who travelled down the White River from Indianapolis reported a stream that made them sick: the city's sewage made up about half its flow, the rotting carcasses of hogs dumped by the packing houses made it worse, and greasy sludge coated its bed. Raw sewage and industrial waste went into the river routinely until the mid-1900s. Since the early 1970s, public and private money spent on sewage treatment, erosion control and reclaiming old mines has brought the water and its fish a long way back, and the river now offers game fishing for bluegill, bass and catfish.

Fishing on the White River. U.S. Geological Survey.

The fish still point at what is left to fix. Kessinger Ditch, Lost River and Clifty Creek have excellent habitat but only fair to good fish communities, and those are the sites where nitrate and atrazine run high.

Sampling fish in the basin. Photograph: Jeffrey Martin, U.S. Geological Survey.

Sources

• U.S. Geological Survey, Circular 1150, "Water Quality in the White River Basin, Indiana, 1992–96," National Water-Quality Assessment Program. Figures and photographs from the report.