Of U.S. origin, the phrase:
– too thick to drink (and) too thin to plow, or to plough
– too thin to plow, or to plough, (and) too thick to drink
has been used in reference to several muddy rivers, and, occasionally, to other waterbodies.
These are the earliest U.S. and Australian uses of the phrase that I have found, in chronological order:
1-: THE MISSOURI RIVER
The first occurrences of the phrase that I have found refer to the Missouri River:
1.1-: From the Poughkeepsie Daily Eagle (Poughkeepsie, New York) of Monday 10th November 1890:
At the Second Reformed Church, Rev. Mr. Hill, on Sunday evening preached another sermon in the series on the life of Christ, based on John i, 32–34: The speaker dwelt principally upon the baptism of Christ in the Jordan, describing the river as he saw it, on his recent journey to the Holy Land. He did not think much of the Jordan. The water was something like the water of the Missouri, too thick to drink and too thin to plow.
1.2-: From the account of the banquet that the Chicago Live Stock Exchange gave to the delegates of the National Live Stock Exchange on Friday 6th December 1895, published in The Daily Inter Ocean (Chicago, Illinois) of Sunday 8th December 1895—Colonel Charles H. Gould, of Miles City, Montana, was quoted as saying:
Major McGinnis, an orator of the Northwest, once said that the Missouri River was too thick to drink and too thin to plow.
1.3-: From The Evening Standard (Leavenworth, Kansas) of Monday 24th April 1899:
Instead of the river falling as predicted in the weather report, it shows a continuous rise, having come up almost a foot since yesterday morning.
The water is now in that condition which John J. Ingalls 1 describes as too thick to drink and too thin to plow.
1 The Republican politician John James Ingalls (1833-1900) represented Kansas in the U.S. Senate from 1873 to 1891.
1.4-: From The Salt Lake Tribune (Salt Lake City, Utah) of Thursday 21st February 1901—the melting snow turned into mud that flowed down the city waterpipes:
The city water was like Missouri river water, that is, it was too thick to drink and too thin to plough.
1.5-: From The Hutchinson News (Hutchinson, Kansas) of Monday 20th October 1902:
H. W. Smith, one of those who went on the G. A. R. 2 excursion to the grand encampment at Washington, has written the following account of the excursion for the News:
[…] At Kansas City we cross the Missouri, or “big muddy” of which some one has said “it is too thick to drink and too thin to plow.”
2 G. A. R.: Grand Army of the Republic, the name of an association of veterans who served during the American Civil War (1861-65).
2-: OTHER U.S. WATERBODIES
The phrase has been used in reference:
2.1-: To a river called Cedar in The Ravalli Republican (Hamilton, Montana) of Friday 10th July 1903:
An eastern exchange sizes up the flood situation as follows:
“More rain, more rest,” is serious jest,
When one wants to fish, ’bout now;
For the water’s riz, and the Cedar is
Too thick to drink and too thin to plow!”
2.2-: To the Mississippi River (with attribution of the phrase to Mark Twain 3) in a letter emphasising the need for water meters, by F. E. Case, a manufacturer, published in The Evening Repository (Canton, Ohio) of Monday 4th March 1912:
“Six cents for a thousand gallons should not scare people from the use of meters and the city could make the rate less if all use meters and it could never be said of our water as Mark Twain said of the Mississippi’s, ‘too thin to plow and too thick to drink.’”
3 Mark Twain (Samuel Langhorne Clemens – 1835-1910) was a U.S. novelist and humorist.
2.3-: To the Passaic River in the Passaic Daily News (Passaic, New Jersey) of Thursday 15th September 1921:
Somewhere in New Jersey there is a river—and there is not the slightest doubt about it. It wends its noisome, slimy way from the upper end of Passaic County down through Patterson, Passaic, Nutley, Belleville and Newark. Its stench assaults the nostrils, and makes life along its banks—and far distant—almost unbearable, particularly during the summer months.
HOW LONG! HOW LONG!
Someone not so long ago said of it:
“The Passaic River; too thin to plow and too thick to drink.”
How long are the people of the Passaic valley going to stand for this stench?
2.4-: To the Horicon Marsh, in Dodge County, Wisconsin, in The Daily Northwestern (Oshkosh, Wisconsin) of Friday 1st February 1924:
The draining that was done took the water off the surface but didn’t lower it into the ground. It made the marsh too thick to drink, but left it too thin to plow; too dry for ducks, but too wet for corn.
2.5-: To the Colorado River in an address that James G. Scrugham (1880-1945), Governor of Nevada from January 1923 to January 1927, gave to the members of the Pilgrim Brotherhood of the Federated Church—as reported by the Reno Evening Gazette (Reno, Nevada) of Thursday 17th February 1927:
A farmer of Clark county has described the river as being “too thick to drink and too thin to plow.”
2.6-: To the Colorado River in Commissioners Inspect Colorado River Levees, published in The Denver Post (Denver, Colorado) of Sunday 1st May 1927:
The commissioner and the advisory board were shown what the district engineers considered the weak portions of the levee. Stops were made at a dozen or more points where the river’s muddy waters, often described as “too thick to drink and too thin to plow,” were slowly scouring away the sand in which the rip-rapping was embedded.
These are the earliest Australian uses of the phrase that I have found:
1-: From The Age (Melbourne, Victoria) of Wednesday 21st April 1937:
Thick, muddy samples of Loddon water, the pollution of which was alleged to have been caused by gold-mining operations, impressed the Minister of Mines (Mr. Hogan) when placed before him by a district deputation yesterday. Mr. Shields, M.L.A., remarked that the water was too thick to drink, and too thin to plough. The deputation was the result of a conference called in the Loddon areas last month to deal with the problem of pollution.
2-: From the Catholic Freeman’s Journal (Sydney, New South Wales) of Thursday 7th October 1937—quoting an article about soil erosion in the USA, by H. C. Forster, Inspector of Agriculture, published in the Journal of Agriculture, Victoria:
The American Red Cross alone have spent over 20 million dollars during the last two years in relief of flood suffering. Millions of tons of once fertile soil have been washed into the rivers. It has been estimated that the famous Boulder Dam which has just been completed at enormous cost will be filled in a century by silt from the muddy Colorada [sic], that river which a rancher once said was “too thick to drink and too thin to plough.” And so the tale might be continued indefinitely.