The presence of nitrate in the water is predominantly a consequence of land management decisions and farming practice.
It means, for example, the benefits from the 1990s' introduction of Nitrate Vulnerable Zones (NVZs), which put controls on the application of manures to the land, cannot properly be assessed for at least another 15 years.
The area around the site of remains "very volatile" because of the presence of ammonium nitrate, according to Matt Cawthon, chief deputy sheriff of McLennan County.
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But it also illustrates just how intractable the issue of nitrate pollution has become.
The record is not simply a picture of nitrate concentrations.
It is clear also from an analysis of the various inputs and outputs over the period that a lot of nitrate accumulated in the catchment has yet to come out.
General Barbero has worked hard with other federal agencies to curb the availability of ammonium-nitrate fertilizers made in Pakistan, since traces of the agricultural chemical have shown up repeatedly in the aftermath of Taliban bombings.
They will measure the amount of carbon, phosphate and nitrate in the soil, together with the rate of plant growth and microbial decomposition.
In the dry uplands of Chile, rich mineral nitrate deposits were then found, and gradually took the place of guano in the late 19th century.
One of the worst disasters in U.S. history involving a form of ammonia occurred in April 1947 when a ship loaded with ammonium nitrate -- a solid fertlizer composed of ammonia and nitrogen -- caught fire while docked in Texas City, Texas, in April 1947.
One is an immediate effect as surface run-off takes roughly 50% of the free nitrate straight into Thames tributaries and the main river.
Clearly visible in the new time series are major land-use changes during the 20th Century that gave enormous nitrate kicks to the hydrology of the Thames basin.
"Anhydrous ammonia will burn but it is unusual for it to detonate, whereas ammonium nitrate has a track record of blowing up, " he told the BBC World Service.
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On 16 April, 1947, a fire on a ship loaded with ammonium nitrate set off a series of explosions in the port of Texas City, and fires that burned for days.
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"Anhydrous ammonia will burn but it is unusual for it to detonate, whereas ammonium nitrate has a track record of blowing up, " explained Prof Andrea Sella, a chemist at University College London.
Levels of key nutrients, such as phosphate and nitrate, are highest in the Midlands, East and South of the country where population density is highest and farming methods the most intense.
Ammonium nitrate, a solid fertilizer composed of ammonia and nitrogen, is also a component of explosives widely used in mining.
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And David Laird, of America's Department of Agriculture, showed that biochar even helped the rich soil of America's Midwest by reducing the leaching from it of a number of nutrients, including nitrate, phosphate and potassium.
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The situation remains volatile because of an extremely dangerous substance, ammonium nitrate, found at the scene, said an official from the county sheriff's office.
Nitrate-rich run-off, for example, can wreck the ecology of lakes.
The general goal of this workshop is a focused review and adoption of a minimum set of QC procedures and QC flags starting with in situ dissolved inorganic nutrients (phosphate, nitrate, nitrite, and silicate) and dissolved oxygen.
An expert on fertilisers at the University of London, Prof Andrea Sella, told the BBC it was possible that the highly explosive ammonium nitrate had also been stored on site.
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