|AS DESCRIBED IN THE NATIONAL REGISTER NOMINATION:
The River Mill Hydroelectric Project, built in 1911 by the Portland Railway Light and Power Company, consists of an assemblage of concrete industrial structures spanning the channel of the Clackamas River in the vicinity of Estacada, Oregon. In continuous operation as a hydroelectric generation facility since construction, the River Mill Hydroelectric Project retains high integrity and effectively relates its original construction and the associations for which it is significant.
The River Mill Hydroelectric Project, built in 1911 by the Portland Railway Light and Power Company and operated by its successor Portland General Electric, consists of an assemblage of concrete industrial structures spanning the channel of the Clackamas River in the vicinity of Estacada, Oregon. In continuous use for its original function as a hydroelectric generation facility since construction, the River Mill Hydroelectric Project has experienced modest alteration and improvement related to improved safety and operational requirements. The project retains very high integrity in use of materials, workmanship, feeling, location, setting, and effectively relates the associations for which it is significant under Criterion "A." The design of the facility, including the earliest known Ambursen-designed hydroelectric dam in the west, although modified to improve seismic performance, nevertheless retains the open interior character that defines the type. As such, the River Mill Hydroelectric Project, including the modified Spillway and Powerhouse dams, retains sufficient integrity to relate the original project design and the associations for which it is significant under Criteria "A" and "C" for listing in the National Register of Historic Places.
The River Mill Hydroelectric Project, completed in 1911 and used continuously as a hydroelectric generation facility for nearly nine decades, is significant for its role in the development of the Clackamas River Valley and the expansion of the early electric trolleys that provided improved access, sett1ement and economic development to this region during the first quarter of the 20th-century. Designed by noted hydroelectric engineer, the hollow slab and buttress dams at the River Mill Hydroelectric Project are additionally significant as the oldest hydroelectric-related examples of the Ambursen type on the Pacific Coast and the best known examples in the region to have been designed by the inventor of the form, Nils F. Ambursen.
The Rise of Electrification
Throughout the first three-quarters of the 19th century industrial development, and to a large extent community building, was substantially the result of proximity to water. Rivers, lakes, and ocean ports provided towns with ready access to goods by providing economical water-based transportation. Flowing water, long a source of motive power for small industrial uses such as water-driven mills, reached a pinnacle of functionality in the 1840s with the development of large-scale systems such as that at Lowell, Massachusetts. In the post-Civil War era, as the Industrial Revolution firmly took hold in the United States, major improvements in transportation and power-generation technologies brought sweeping change to the character of American cities and how they developed. Key among these "modern" improvements was the early-1880s invention and construction of entirely new systems for the generation and distribution of electrical power. Once established, the ready availability of electricity freed American industry from the limited water-based sites then available and greatly expanded the economic base of the nation. Beginning in the late 1880s and early 1890s, the development of electrified interurban transportation systems, coupled with the widespread adoption of home lighting and new labor-saving electric appliances, changed the daily life of the typical American as has little before or since.
In the year following Thomas Edison's 1879 demonstration of an incandescent lamp at his Menlo Park laboratory, a series of rapid advances led to the development of commercially viable electrical generation and distribution systems that could be constructed around the nation and dozens of entrepreneurs entered sought to capitalize on the birth of a new and promising industry. In 1880, one of the earliest hydro-electric turbines was installed in Grand Rapids, Michigan, soon followed by a system at Niagara Falls, New York.
Electric Generation and the Development of the Clackamas River Area
Settlement in the Clackamas River valley, often called the "Estacada County," was limited throughout Oregon's pioneer period, with sparse homesteads along the Barlow Trail and scattered attempts at agriculture in the narrow creek valleys that feed the river. In the 1840s, the Currin brothers built a cabin south of Eagle Creek and established a store near what eventually became known as Currinsville, marking the first permanent settlement in the area. In 1859, a bridge across the Clackamas River was established near the mouth of Eagle Creek, "...where an island with riffles made shallower water," (Dillon: cl936). Cyclically replaced and improved following flooding and increasing use, this bridge crossing remained a focal point for transportation across the river through the remainder of the 19th century and ultimately served as the focus for the establishment of the town of Estacada. (Lynch, 1973:271)
The development of the City of Estacada, even today the sole incorporated community in the upper Clackamas region, is integrally linked to the generation of hydroelectric power on the Clackamas River. In the latter years of the 19th century, Portland grew increasingly reliant upon an extensive network of trolleys for transportation and, predominately running upon electricity, this network spurred intensive needs for increasing electrical capacity in the region. As the output of smaller plants was over-extended, new sources on the Clackamas came to the fore and in 1901, George W. Brown, chief engineer of the Oregon Water Power Railroad Company, set out to explore the upper Clackamas River country for potential water power sites. On the homestead of John Zobrist, whom Brown had conveniently employed as a guide, he ". . . found a spot where the current was swift and the location looked ideal for a dam." (Lynch 1973:356) Brown enticed Frederick Morris, of Morris Brothers Investment Bankers, a prominent Portland firm with previous experience in financing railway development, into financially supporting the concept, and plans were made for the construction of a dam and hydroelectric facility. First, Oregon Water Power hired L. R. Meyers to build a railroad line to the dam site, to be known as "Cazadero," that would allow for both the transport of construction materials in and shipment of locally milled timber goods from a mill the Morris established in the area. O. B. Coldwell, then a vice-president of the Oregon Water Power Railroad Company, named the new dam "Faraday" after the famed scientist. In 1903, the power company filed a plat for a new townsite near its development, built a hotel at the end of the railroad line, and encouraged “excursion" use to promote development in the Upper Clackamas area. The City of Estacada was incorporated in 1905.
Various stories documenting the origin of the name of "Estacada" cloud its true origin. "Estacada is a Spanish word and means “staked out, or marked with stakes” and the principal use in the United States is in northwestern Texas. The Spanish name refers to the trunks of an upright desert plant that remain standing like stakes or poles. The name was used in Oregon because it had a pleasing sound with no thought of its original significance." (McArthur, 1982:260) The most reliable account of the city's moniker credits its origin to George J. Kelly, an employee of Mr. W. P. Keady, the right-of-way and land agent for the Oregon Water Power Townsite Company, an element of the power concern. In December 1903, at a meeting in Keady's office, Kelly suggested naming the town Estacado. Some versions claim that an error in the engineering department when drafting the town plat, resulted in the change to a terminal "a' while other sources claim that Kelly himself was responsible for the change.
While the initial hydroelectric development on the Clackamas was begun by the Oregon Water Power Railroad Company, it was a larger firm, formed by the merger of OWPRC and the Portland General Electric Company, among others, that would actually see the first transmission of hydropower from the Upper Clackamas, beginning with the construction of the Faraday or "Cazadero" plant in 1907. Four years later, again faced with increasing demand the second plant on the Clackamas, at River Mill, was completed.
PCE & Predecessor Corporate Context
Portland had early shown an interest in the generation of electric power and its potential uses. Entrepreneur Henry Villard (principal of the Oregon Navigation and Railroad Company, for a time the owner of the canal at the Willamette Falls) had traveled to Edison’s workshop in 1880 and witnessed the inventor's first public demonstration of the incandescent lamp. Villard saw the potential of electricity as a spur for massive economic development in Oregon and determined to promote its use. For his return to Portland, Villard had Edison outfit his ship, the Columbia, with a dynamo and a series of brush arc electric light, Edison's first commercial order for electric generation equipment. (Tollefson, 1987:20) Docking the Columbia near downtown Portland, Villard had wires run from the ship to the Claredon Hotel and advertised the "blazing" new lights to an enchanted city. “The powerful rays lighted up the whole neighborhood to the brightness of day. Thousands visited the light and the vessel.” (Oregonian, 4¬September-1880)
Demand for electric power, almost exclusively for lighting, swept Portland. Soon various industrialists hooked generators to their internal power plants and offered limited power to light offices and homes in the downtown. Most of these early attempts at electrical generation used steam and the power served only a limited area and was usually available only in the evening.
In 1888, two early area-power providers, the Oregon City Electric Company and the United States Electric Lighting and Power Company, joined forces, merging the teeming customer base of the Portland area with the seemingly inexhaustible supply of power available at the Willamette Falls. “A very important step in the entire future of the electrical industry was taken when in November, 1888, Oregon City and Portland capitalists united in the organization of the Willamette Falls Electric Company, with [E. L.] Eastham as president and Parker Morey as superintendent.” (Coldwell, 1941:289-90)
The pioneering efforts of the Willamette Falls Electric Company between 1889 and 1890 firmly established the potential of the Willamette Falls as the major source of electricity for the city of Portland. Beginning in 1893 and 1895, the reorganized and expanded company (now known as the Portland General Electric Company) built a second, significantly larger plant, known as Station B. By 1903, Station B provided Portland General Electric with the vast majority of its power, and boasted a capacity of 5,730 kW. (Greisser, 1982:6-7)
By the early 1900s, the role of electric-powered trolleys became increasing significant in the development of Portland and its surrounding communities. New organizations sought permits to operate such networks within the city and Portland General Electric, which provided power not only for its own trolleys but also sold electricity to its competitors, faced ever increasing demands on its generating capacity. This was exacerbated by the crowning success of the 1905 Lewis and Clark Exposition, overseen in large part by Henry W. Goode, President of Portland General Electric after Parker Morey's retirement in 1902. Goode's involvement and the demonstrations of electrical appliances and lighting at the fair brought additional respectability to the company and increased ownership of the new "labor-saving devices" of the era. Portland's population also boomed following the Exposition, as area visitors chose to relocate and invest in the rapidly advancing community. “Not only did [the Exposition] 'place Portland on the map,' so to speak, but it achieved the greatest financial success of anything of the sort ever held in Oregon…over 2,500,000 visitors passed through the portals, including 135,000 from east of the Mississippi River.” (MacColl, 1976:261)
Against the backdrop of the rapid growth of Portland and the Willamette Valley, an area increasingly reliant on its extensive network of interurban railroads, the need for additional generation capacity in the early years of the 20th century created a serious competition among varying interests. One of the largest of these was the Oregon Water Power & Railway Company. “The potential for power development on the Clackamas River was recognized at the turn of the century. [Its] power sites were in relatively close proximity to Portland and to projected electric interurban lines. Thus, surveys were started in June 1901.. .and in 1902 property acquisition began for the hydroelectric generating project then named Cazadero. (Greisser, 1982-35)
As already noted, the Oregon Water Power Railroad Company established the new city of Estacada as the terminus of its wood-burning steam railway line running east from Portland and was offering low-cost excursion and tourist fares to the community as early as 1902, building ridership and freight traffic in anticipation of the construction of its power plant.
In the early years of the 20th century, Parker Morey and Portland General Electric Company, still the largest of the area's electrical providers, did not stand idly by while its competitors explored new sources of generation. Between 1900 and 1910, Portland's population grew over 100%, from 90,426 to 207,214 with similar rates of growth throughout much of its surrounding area. (State of Oregon, 1914: 147) Uneasy with his company's complete reliance on the Willamette Falls plant, Morey had begun development of "Station C," a steam plant in northwest Portland, in 1901, and Stations "D" and “E,"
also Portland steam plants, between 1904 and 1905. Morey's successor Henry Goode, perhaps sensing the potential growth to be brought about by the Lewis and Clark Exposition, set in motion of series of events that would greatly expand the company's generation capacity. Chief among these would be the creation of the Portland Railway Light & Power Company, formed in 1906.
The Portland Railway Light & Power Company was a truly massive enterprise for its day. Capitalized with substantial eastern monies, the new utility company combined the assets and operations of Portland General Electric with the Oregon Water and Power Company, the Portland Railway Company, and a number of other firms that in total represented the combined interests of more than thirty-six earlier railway operations, power providers, and related entities. Essentially, the formation of the Portland Railway Light & Power Company established a complete monopoly on such services in the greater Portland area. “Every electrical light, power and traction company in the lower Willamette Valley has been merged into one vast consolidation of interests. Every mile of electric railway, every horsepower of electric energy generated within a 5O-mile radius of Portland, have been brought under the same ownership and will be operated by one management." (Oregonian, 4-May-1906)
By joining with the Oregon Water Power Railroad, the former Portland General Electric Company fell heir to the potential of the Clackamas River and immediately took over the on-going hydroelectric development at Estacada, rushing to complete a plant to augment its overburdened Station B at Willamette Falls. Once Station "G", the Faraday plant, was completed in 1907, the railway line to Cazadero was electrified and service to the Clackamas Valley area was dramatically improved, spurring increased development. (This initial generation facility on the Clackamas was first known as "Cazadero," then re-designated Station "G" and finally termed "Faraday," the name by which it is currently known.)
Increased settlement and commercial development in the Estacada area during the first two decades of the 20th century was aided, in large part, by the efforts of the Portland Railway, Light & Power Company itself. (The corporate identity created by the 1906 Portland Railway, Light & Power Company name is fairly indicative of the company's priorities and self-image. This was largely a transportation company, that providing lighting and generated power solely as a means toward efficiently providing those services to its riders and customers.) The company, which owned substantial lands in the region, sought to increase settlement and commercial use both to sell property and create a steady commuter volume that would help offset its own use of the line for freight and service. Toward that end, Portland Railway Light & Power offered special weekend fishing and recreational packages on its Estacada line and published promotional leaflets throughout the first decade of the century. One, titled Health: Wealth & Happiness on Ten Acres, was published in 1908, only a short time after the completion of the Faraday plant, to encourage residential development.
“The building of this railroad throws open to the homeseeker a veritable paradise of opportunity where he may realize the fondest hopes of his dreams - whether it be a cosy (sic) home on a ten-acre tract within a few minutes ride from the heart of this big city, or a more extensive farm, or a dairy ranch, ora fruit orchard, or a poultry ranch, or land for any other purpose...” (PRL&P Co., 1908)
In the years before Henry Ford's production of the Model "T," the first truly affordable automobile for the average American, electric trolleys and railroads formed the backbone of the nation's transportation system. This was especially true in the far-flung, young, cities of the western United States and Portland was a classic example of the phenomena. One of the major entities that joined to form Portland Railway Light & Power, was the Portland Railway Company, a concern that in 1906 included the assets of twenty-eight separate predecessor lines dating back to 1882. (Wollner, 1990:69) In its heyday, Portland's railway system was a major element of the city's character and daily life. “The presence of the trolleys on city streets, and in the countryside, at least for the first fifteen years of the new century, represented convenience, adventure, and freedom. Trolleys did what machines should do - they made life easier and better. They were quick, clean, and cheap. By all accounts, Portland Railway Light and Power owned one of the best, most complete railway systems in the country.” (Wollner, 1990:80)
By 1922, in the twilight years of Portland's electric railway period, the Portland Railway Light & Power Company boasted that its trolleys served an area of over 800 square miles, with 32 separate city street car lines and four interurban lines, offering a combined 341 miles of track. “In 1922 [Portland Railway Light & Power Company] carried 90,156,701 revenue, transfer and free passengers on its city lines and 3,474,013 [passengers] on its interurban lines for a total of 93,900,714 passengers.” (PRL&P, 1922)
THE RIVER MILL DEVELOPMENT
In December 1909, the Portland Railway Light & Power Company acquired from the Portland Water Power and Electric Transmission Company and the Morris Brothers some 1642 acres of property and the development rights near Estacada that would eventually become the River Mill Hydroelectric Development. The construction of this facility, to be the company's second on the Clackamas River, would augment the Faraday development at Cazadero and help meet the ever-increasing demand for power being placed on the company's system. “The railway company will proceed at once with the development of the water power plant on the property acquired near its Cazadero plant and expects to have it in operation by September 1, 1911. [According to B. F. Joselyn, President of the Portland Railway Light & Power Company], "It is possible that the dam to be erected at the Estacada, or Morris site, will be of hollow concrete construction, a departure in dam building. On my trip East, I went to Ellsworth, Maine and inspected a hollow concrete dam in use at that point and found it to be giving perfect satisfaction and its cost materially less than that of a solid concrete dam." (Oregonian,3-December-1909)( Nils F. Ambursen design for a slab and buttress or "hollow" dam at Ellsworth, Maine for the Bar Harbor Power Company was completed in 1907. (National Dam Inventory, 10 #ME00026)
Built as Joselyn anticipated of hollow "flat slab and buttress," construction, the River Mill Dam is more correctly termed an "Ambursen" dam after Nils. F. Ambursen, the engineer who patented this influential design. Puget Sound Bridge and Dredging Company of Seattle, Washington served as the general contractor and Sellers and Rippey, consulting engineers of Philadelphia were responsible for the design of the project. The spillway and powerhouse dams themselves were designed and licensed by the Ambursen Hydraulic Construction Company of Boston, Massachusetts. The Portland Railway Light and Power Company served as its own contractor for the installation of mechanical and electrical equipment. The River Mill Dam is 936 feet long spanning the Clackamas, and stands 85 feet high. The spillway section is 405 feet wide, including splashboards. Construction of the River Mill dam was begun in June 1910 and completed eighteen months later in November 1911. (Greisser, 1982:38) The total cost of the dam was $1,011,746.29. (PG E Files, 5-23-1912). “Upon its completion, the River Mill project gained immediate notoriety for its design "...for the rapidity of its construction, considering the exceedingly substantial manner in which its is built, and for the fact that it employs the first Ambursen type of dam for power plant work on the Pacific Coast." (Journal of Electricity, Power and Gas, 4-January¬1913, as cited in Greisser, 1982:38)
NILS F. AMBURSEN AND THE "HOLLOW' DAM
During the 1895-1915 period of hydroelectric expansion in the United States, dubbed "Innovation and Experimentation" by historian Duncan Hay, a variety of attempts were made to both increase capacity of hydroelectric facilities while lowering costs and shortening times in the construction of badly needed new plants. One innovation of lasting impact was the invention of the hollow-core slab and buttress dam by engineer Nils F. Ambursen. Born in Frederickstad on 6-February-1876 and educated at the Civil Engineering College at Skien, Norway, Ambursen migrated to the United States by 1896 and became a naturalized citizen in March 1902. Gaining experience in dam construction as an employee of the B. F. Sturtevant Company, in 1903 Ambursen designed the Theresa dam, the first concrete slab and buttress dam ever, for Snell and Makepeace at Theresa, New York. (AJI information on Ambursen and the Ambursen Construction Company, unless otherwise noted. is to.ken from N. F. Ambursen, Condensed Record of Education, Training, and Experience, 1934, as supplied by Ambursen's daughter, Mrs. Frances A. Ambursen, of Mitchellsville, Maryland.) “.. . buttress dams act as gravity structures but are designed to take advantage of the vertical component of water to achieve structural stability. The amount of material in the dam is reduced by building a series of discrete buttresses spaced from 15 to 70 feet apart. The inclined upstream face is then built across the front of these buttresses . . .As a result, buttress dams are often referred to as hollow dams because of the hollow spaces between the buttresses. . . The earliest flat-slab buttress dams were designed by Nils F. Ambursen and his company, the Ambursen Hydraulic Construction Company, hence they are often called Ambursen dams. (Jackson, 1988:50-51)
Following the completion of the Theresa Dam, a description of the new design was published in the November 1903 Engineering News Record. "The article created such widespread interest amongst engineers and others that I found it necessary to organize the Ambursen Construction Company." (Ambursen, 1934)
Joining forces with William L. Church, a Professor of Civil Engineering at LeHigh University and formerly a partner in Westinghouse, Church, Kerr and Company, Ambursen filed a patent on the new dam that bears his name. "While with the Ambursen Company, I held the position of vice-president and Chief Engineer, and was in full charge of all engineering and construction...No plans nor contracts could be executed without my approval." During its existence under the original partners from late 1903 through 1917, the Ambursen company built more than 100 dams in North America and the design gained a substantial reputation. In 1917, following his invention of a system of steel forms for building construction, Ambursen left the firm and established the Uni-Form Company, soon purchased by Blaw Knox of Pittsburgh, Pennsylvania. In 1922, Ambursen returned to private practice, consulting on the design of hydroelectric facilities for a wide variety of clients. These included the Ambursen Hydraulic Construction Company although he retained no formal association with the firm after 1917. ( See S. W. Stewart, President, Ambursen Hydraulic Construction Company, "Copy of Recommendation" 12-August-1 933. Nils F.) Ambursen died in Washington D.C. at 81 years of age in January 1958.
According to information compiled by Mr. Amburs.en in 1934 under the heading "Partial List of Construction Projects with which N. F. Ambursen has been identified," he was involved with projects ranging from a storage lake in British Columbia to a hydroelectric facility for the Puerto Rico Light and Power Company. The bulk of Ambursen's work, however, was located in the eastern Untied States, particularly in the Northeastern states of Maine, New York and New Hampshire. The River Mill Dam is the oldest, and apparently sole surviving, of the three identified Ambursen projects in the United States built west of the Rocky Mountains. (The others are a hydro-electric facility for the Big Horn Power Company in Shoshone, Wyoming and an irrigation dam for the La Prelle Reservoir and Ditch Company in Douglas Wyoming. Neither appear to survive. It should be noted that while not directly identified with Ambursen, at least one "slab and buttress" hydroelectric dam in the western United States is identified in FEMA's National Dam Inventory is listed as pre-dating River Mill; the low-head 1907 Shoshone Falls Dam in Jerome County, Idaho. (See National Dam Inventory, NID #ID00050) There are a total of 79 slab and buttress hydroelectric dams, or less than one-half of one percent, within the 75,000+ identified dams in the United States.)