The First Vision
The first official interest in creating Rock Creek Park stemmed from dissatisfaction with the White House.
By the 1860s the executive mansion, less hallowed by tradition than it would later become, was judged to have serious shortcomings. As yet unexpanded by wings, the house accommodated offices as well as rooms of state and living quarters, yielding presidents and their families little privacy. The pestilential Washington City Canal along present-day Constitution Avenue disgorged its wastes in the shallows of the Potomac River directly below the mansion grounds (reclamation of the Potomac flats to fill in the Washington Monument grounds and create Potomac Park was a generation away). To escape this crowded and unhealthful situation, President Abraham Lincoln often removed to a cottage at the Soldiers Home, north of the Capitol beyond the old Washington City limits.
On June 25, 1866, the United States Senate directed its Committee on Public Buildings and Grounds "to inquire whether a tract of land of not less than three hundred and fifty acres, adjoining, or very near this city, can be obtained for a park and site for a presidential mansion, which shall combine convenience of access, healthfulness, good water, and capability of adornment." Sensing that it may have overly limited its options, the Senate passed another resolution five days later lowering the minimum size to 100 acres. Then realizing the need for professional landscape gardener or topographical engineer to examine the different tracts of land offered to the committee" and to report on their suitability for the desired purpose. 
Sen. B. Gratz Brown of Missouri, chairman of the Public Buildings and Grounds committee, asked Secretary of War Edwin M. Stanton to detail a Corps of Engineers officer to the task. The assignment fell to Maj. Nathaniel Michler, a West Point graduate who had been breveted brigadier general for Civil War service. After examining "the many beautiful localities to be found in the vicinity of the capital, and having caused an accurate and detailed survey of its environs to be made," Michler submitted his report to the committee on January 29, 1867. 
Departing from the apparent intent of the Senate, Michler chose to separate the subjects of the presidential mansion site and the park. The mansion should be a secluded retreat, he suggested, whereas the park should be generally accessible. His primary interest was evident from the greater attention and eloquence he lavished on the park proposal, beginning with his brief for urban parks in general:
Where so much has been written on so interesting a feature to any large city as that of a park, and where the necessity of public grounds, either for the sake of healthful recreation and exercise for all classes of society, or for the gratification of their tastes, whether for pleasure or curiosity, has become apparent to every enlightened community, it would seem to be unnecessary for me to dilate further upon the matter, to say nothing of the natural or artificial beauties which adorn a park, and so cultivate an appreciative and refined taste in those who seek its shades for the purpose of breathing the free air of Heaven and admiring nature. It certainly is the most economical and practical means of providing all, old and young, rich and poor, with that greatest of all needs, healthy exercise in the open country. To accomplish these ends there should be a spaciousness in the extent of the grounds, not merely presenting the appearance of a large domain, but in reality possessing many miles of drives and rides and walks. There should be a variety of scenery, a happy combination of the beautiful and picturesque--the smooth plateau and the gently undulating glade vieing with the ruggedness of the rocky ravine and the fertile valley, the thickly mantled primeval forest contrasting with the green lawn, grand old trees with flowering shrubs. Wild, bold, rapid streams, coursing their way along the entire length and breadth of such a scene, would not only lend enchantment to the view but add to the capabilities of adornment. While nature lavishly offers a succession of falls, cascades, and rapids to greet the eye, as the waters dash through some romantic dale, the hand of art can be used to transform them into ponds and lakes as they gently glide through the more peaceful valleys What so useful as an abundance of water, or so ornamental when converted into fountains and jets to cool the heated atmosphere? It furnishes, also, opportunities for the engineer and artist to display their taste in constructing ornamental and rustic bridges to span the stream. 
The valley of Rock Creek in the District of Columbia, Michler found, lent itself admirably to park treatment:
All the elements which constitute a public resort of the kind can be found in this wild and romantic tract of country. With its charming drives and walks, its hills and dales, its pleasant valleys and deep ravines, its primeval forests and cultivated fields, its running waters, its rocks clothed with rich fern and mosses, its repose and tranquility, its light and shade, its ever-varying shrubbery, its beautiful and extensive views, the locality is already possessed with all the features necessary for the object in view. There you can find nature diversified in almost every hue and form, needing but the taste of the artist and the skill of the engineer to enhance its beauty and usefulness; gentle pruning and removing what may be distasteful, improving the roads and paths and the construction of new ones, and increasing the already large growth of trees and shrubs, deciduous and evergreen, by adding to them those of other climes and countries. 
In his further description of the valley, Michler elaborated on how its natural qualities might be improved upon:
Rock creek winds for more than four miles through the centre of the proposed grounds, receiving at the convenient points the waters of the Broad and Piney branches, and several smaller tributaries. For a short distance it courses through a narrow but beautiful valley, then wildly dashes for a mile over a succession of falls and rapids, with a descent of some eight feet, the banks on both sides being bold, rocky, and picturesque; then passes again though narrow valleys or between high, bluff banks. At many points the creek is capable of being dammed, thus forming a series of lakes and ponds for useful and ornamental purposes. The many deep ravines setting in towards it can furnish romantic walks and quiet retreats for the pedestrian. The larger part of the ground is thickly wooded, and capable of great adornment. Here we find the several varieties of oak, the beech, the locust, the mulberry, the hickory, the sassafras, the persimmon, the dogwood, the pine, with a great many shrubs, vines, and creepers Beautiful vistas, artistically arranged, can be cut through them, exhibiting distant points of landscape, while charming promenades can invite the wanderer to seek cooling shades. Nature has been so rich in her vegetable creation that the plan of transplanting trees of large growth, which has been adopted in most of the modern parks, will be unnecessary Here and there some prominent point offers commanding views of the surrounding country, where observatories can be located, conservatories built for exotic plants, and geometrical flower-gardens planted. Back from the stream some level plateaus extend, which can be appropriately employed for zoological and botanical gardens, grounds for play and parade, and many other useful purposes. 
Michler urged swift action to acquire sufficient land before it became occupied by "costly suburban villas." He outlined two park alternatives. The first, embracing 2,540 acres, would include several of the Civil War defenses of Washington, "which have become historical, and from the parapets of which extensive views can be had." He estimated the acquisition cost at $508,000. The second, "[i]n case my recommendations should be considered too extravagant," encompassed 1,800 acres at an estimated cost of $360,000. Another $100,000 would be needed initially for enclosing the grounds, improving and repairing existing drives and walks, and constructing others. 
Senator Brown immediately introduced legislation to acquire a tract "along and adjacent to Rock creek embraced within the limits and designations of the survey made by Brigadier General N. Michler...for the purposes of a public park, free to all persons under such regulations as to police and government as may by proper authority be established." The bill would constitute a committee of Maj. Gen. Montgomery C. Meigs, Maj. Gen. Horatio G. Wright, and Michler to negotiate with the landowners and make purchase agreements. The agreements would be subject to congressional approval. The bill provided for no appropriation (nor did it make any mention of a presidential mansion site). 
Brown brought his bill to the Senate floor on February 19. "The character of the ground around and adjacent to [Rock Creek] is exactly suited to the purposes we desire," he told his colleagues. "It has running water; it has rugged hills; it has picturesque scenery; it has abundance of varied forest timber; it has a native undergrowth blushing with beauty. It has the tangled vine and the clustering wild-flower, and the quiet mosses gray with age, and indeed a thousand imprints of native adornment that no hand of art could ever equal in its most imitative mood." 
Rising to still greater heights of rhapsody, Brown proclaimed the special value of the proposed park to congressmen and government officials:
Those who, for any length of time, have undergone the wear and tear of such life as this, who have all their energies run to brain, and all their souls fused into politics, need not be told that anything which holds out hope of either mental or passional relief is seized upon with avidity. How necessary, then, that all the ennobling influences of nature--the scenic splendor or shifting views, the life and animation of gay concourse, the uprisen majesty of the forest, the intoxicating gladness of spring flowers, the laugh of the heavens through playing branches, the shimmer of the waters, the song of birds, graceful forms, inspirations--should be so abundantly grouped around this nation's capital I would have you, Senators, inaugurate a public park that shall have no rival anywhere for beauty or extent or ornamentation, as it will have none for the illustrious character gathered from a whole continent in the after time to wisely rule our republic from this center of its power.
Like Michler, Brown counseled haste to acquire the land before its increase in value, "now that the uncertainty with which sectional discord and disunion so long threatened the stability of the capital has passed away." The cost would be less than $500,000, he stated--"a mere trifle of expenditure for 'a thing of beauty' which will prove 'a joy forever."' 
Not all were moved by Brown's appeal. "We know very well how much below the actual costs of lands that the Government proposes to buy are the estimates that are made beforehand of what they will cost...," Sen. Samuel J. Kirkwood of Iowa retorted. "I think these lands will not cost us much less than a million dollars to begin with, and God knows how many millions it will cost to improve them Let us wait until the country is in a more flourishing condition before we do it." 
Although the Senate passed the bill the next day by a vote of 28 to 7, Kirkwood's position prevailed. The House tabled the bill in the last hours of the 39th Congress on March 2.  B. Gratz Brown did not return to the next Congress, and the measure was not reintroduced by another champion.