The Canal and the Environment

Environmentally, a canal is more than a cross-country ditch; it collects water from one place and takes it to another; it receives and transports sediments and pollutants; it affects land use in the area influenced by its commerce; it is affected by floods and droughts; it may enhance or detract from the landscape. The difficulty in addressing environmental impacts begins with simple listing of the possibilities, and requires identifying the major factors out of a potentially endless number of possible effects. Even in this report that looks only at the hydrological aspects, it becomes difficult enough to identify most of the major interactions between the canal and its environment, let alone all of them. Within constraints of available information, account is taken of the impacts posed in the report of the Commissioners of 1811 such as water supply, floods, sedimentation, and water quality, and of other consequences that emerged during the operations and after abandonment.

WATER SUPPLY

The same belief must have been widely held at the time. John Stevens, of Hoboken, the well-known inventor who foresaw the rapid obsolescence of the canal, also warned the Commissioners that its water supply may-fail: "It is a notorious fact that tracts of country become more or less arid as they become cleared of timber."

The Commissioners of 1816, who prepared the final design, tried to resolve the uncertainty about the future of the water supply, not in disputing the adverse effects of deforestation, but in arguing that springs and lakes are immune to it. They referred to the feeders in the following terms: (1816-17 As. Jour. 40th sess., p. 340) "some of which are outlets of lakes, and others originate from perennial springs in high lands, and will never be affected by the clearing of the country," an ad hoc argument that may reflect some lingering medieval mystery about the sources of springs (Biswas, 1970).

The anxieties over the adverse effects of deforestation expressed by the Commissioners of 1811 were frequently restated by the others who followed. Indeed, one of the reasons given for setting aside the Adirondack Forest Preserve in the 1880's was to maintain a steady flow of water to the Erie Canal. By that time contrary opinions had emerged, as stated, for example by the State Engineer. "An idea seems to have found lodgment in the public mind, that the preservation of the forests in the Adirondack Region, is the only means by which an adequate supply of water for the State canals I I I can be secured for all time." Although preservation would be justified for game, health, and recreation, the benefits would not include water supply which could be obtained from impoundments by dams. "The facts show most conclusively that, from forty to fifty years ago, when the forests of the Adirondack Region were in their primitive state, they were much less reliable as a source of water supply, than they have been during the past few years." (1884 Sen. Doc. 9, p. 22 et seq.).

Despite the assurances of the early Canal Commissioners "Now all experience shows" (1821 As. Jour. 44th sess., p. 868), Rafter's definite assertions near the close of the 19th century (1897 As . Doc. 73, P. 667) that deforestation "has materially reduced the minimum runoff," and the contrary certitudes of the State Engineer, just quoted, that "The facts show most conclusively," very little certainty actually was possible; facts and experience were and in some ways remain few and inadequate.

The extensive and intensive deforestation and land development of the 19th century kept the subject alive and the lack of systematic records kept it controversial. Experience with attempts to resolve the effects of land-use changes upon stream regimen has shown that the effects of manmade changes are heavily masked by those variations in, flow caused by the natural recurrent storms and droughts. To screen out-to separate-the artificial from natural requires long series of observations, and it was only after these land developments had taken place that there was sufficient interest in the potentials of power generation, in availability of water supplies, and in flood protection to warrant continuous stream gaging.

The many spot measurements of streamflow that were made to estimate the available supply of water, if compared with modern data could be instructive on this point. Difficulty arises even for the few flow data that were actually reported, because these spot measurements were higher than the minimums that they were taken to be. For example, Daniel Marsh (1854 As. Doc. 63, p. 147) reported measurements of the flow of the Genesee River at Rochester which he made during July and August 1846 in the course of litigation as to water rights on that river, giving, as he stated, "24,842 cubic feet per minute (414 cfs) for the whole volume of the river at low water."

Marsh also measured a flow of -14,370 cfm on August 24, 1846, (p. 156), but he averaged this figure with several higher measurements and, because diversions were made from the river to the Genesee Canal, the calculation of natural flow became so complex that it is difficult to judge from the facts given what the reported flows actually represent. Nevertheless, the reported flows can be compared with later records. A flow of 414 efs is exceeded by two-thirds of the flows of the Genesee River at Rochester during July and August, and is about twice the minimum of record. Rafter (1905, p. 182, 494) saw in this fact that the low flows of the Genesee River had been markedly reduced by reason of the deforestation of the catchment during the 19th century. It would be simpler to conclude from the precipitation and flow measurements that 1846 was not a particularly dry year: annual precipitation at Rochester in 1846 from climatological records was 37 inches, average of record is 32 inches; precipitation for July and August 1846 totaled 6.34 inches, average of record for this 2month period is 5.5 inches.

A further comparison can be made. The systematic record reported by Jervis on Madison Brook (Madison County) for the year 1835 gave a total runoff of 18.5 inches. Modern records on streams in that region indicate a range in annual flows from 15 to 30 inches, about a mean of 22 inches. The record for the single year,' 1835, falls well within the modern range.

Considering the extent and duration of controversy that the subject engendered and the assertions made, an answer through research was long delayed. The Wagon-Wheel Gap deforestation project in Colorado (Hoyt and Troxell, 1934) demonstrated that deforestation increased water yield.

In the 1930's, the Department of Conservation of New York State and the U.S. Geological Survey began a project to determine the hydrologic effects of the reforestation of abandoned farmland that had been acquired by the State for the growth of trees in the central part of the State. Three small experimental catchments were established together with a control catchment in which land-use practices remained substantially unchanged in an unforested condition. Measurements were made of the rainfall and runoff from each of the four catchments. The results of some 20 years of observation showed that the total annual runoff from the three study areas (partially reforested) was decreased by a significant amount. Peak (that is, flood) rates of flow were also decreased but only in the dormant season; summer floods were unchanged. No changes were noted in the seasonal low flows of the streams in the partly reforested areas. The reduction in the total runoff was attributed to the increased interception and transpiration by trees in the reforested areas; the reduction in the peak flows during the dormant season was attributed to the evaporation of snow caught in tree branches and to the delayed melting of snow in the forest relative to the open areas (Schneider and Ayer, 1961).

A summary by Hibbert (1967) of the results of many studies was simple and direct: "Taken collectively, these studies reveal that forest reduction increases water yield and that reforestation decreases water yield." All answers are not at hand or obtainable. For example, one can no longer determine the hydrologic effects of clearing the virgin forest of New York State or whether these effects are just the opposite of reforesting farmed out land. Nevertheless, the fears expressed by the Commissioners of 1811 and their successors proved unnecessary.

EXTERNAL EFFECTS OF CANAL LEAKAGE

Since the water level of the canal generally stood higher than the countryside through which it passed (see fig. 8 and section on "Canal Leakage"), bank seepage occurred generally over the entire length of the canal. Burrowing animals were especially troublesome. The absence of wide reaction at -first to the effects of the leakage from the canal suggests that it did not create a significant external problem. Few accounts of damage were found in the early record, as the canal was put through while the country was still open, and settlers would naturally enough adjust to conditions as they found them, considering the canal as a benefit. Such claims as were made were small as, for example, 4 acres of farmland between the canal and the Mohawk River near Fultonville were waterlogged by bank seepage. The legislative report on the claim (1848 As. Doc. 45) noted that special legislation to indemnify the farmer was needed because there was neither precedent nor authorization for action in this case. The major problems emerged later.

State Engineer E. Sweet (1888 As. Doc. 25, p. 13) referred to extensive damages to private property arising from leakage, concluding that the large sum paid annually for damages could be avoided "by moderate expenditures for drains and ditches." Landreth (1900, p. 568) reported extensive swamps were formed on both sides of the Jordan summit level during the navigation season. Many wet low places were noted by the author in 1974 where the canal alinement had been rectified so as to leave space between the natural hillside and the banks of the canal.

OPEN SEASON FOR NAVIGATION

Unlike the anxieties expressed by the Commissioners of 1811, the environmental hopes of the 19th century settlers often exceeded their fears. For example, the settlers of the Western Plains expected that "rain will follow the plow"-or if not, then the ,'magnetic telegraph," or at least the railroad tracks (Powell, 1878, p. 70). So it was that the Commissioners of 1824-25 viewed the canal's climatic handicap-winter ice. The builders of the Erie Canal expected that the ice-free season -of navigation would become longer,

"if the same changes of climate are produced in our country (and those changes appear to be rapidly progressing), by the cutting down of the forests, as have been produced in France, Germany, Italy and other countries, by the same process, our annual season of navigation will ultimately be extended to 250 or 275 days."

On the average, the Erie Canal was open for navigation between late April and early December, making a navigation season of about 220 days. Actual dates of opening and closing varied from year to year, and were necessarily defined officially, based on appearance. The date defined for official opening (completion of repairs, refilling, lock services, and so on), caused some chafing among boatmen anxious to start; but choosing a date for closing the canal was a degree more troublesome. Too early and navigation suffered; too late and a sudden freeze entrapped loaded barges en route, as happened on a few occasions, namely:

1824 "15,000 bbl. of flour detained month of December by ice between Utica and Hudson" (Report dated 4 Mar. 1825, p. 8).

1828 Longest navigable season, March 27 to December 20, 269 days.

1871 Canals suddenly closed by extreme cold; 800 boats laden with merchandise frozen in. 1875 Shortest navigable season on record; opened May 18, closed on account of snow and ice, November 24, 191 days.

1880 Closed November 21 by ice.

During its earliest days, in the 1820's, the open season averaged about 240 days. Contrary to the expected effect of deforestation, the season progressively shortened to about 212 days in the 1880's. The closing date, more sensitive to temperature then the opening date, averaged around December 14 at the beginning of operations, and December I at the end of the century. The trend corresponded with the worldwide cooling during that epoch which reached minimum temperatures during the 1880's (Hoyt and others, 1935).

FLOODS

Floods present the greatest environmental danger to inland canals, a fact anticipated by the Commissioners of 1811, who noted (p. 19) that "floods, which pouring a torrent into a canal and tearing down its banks, might at once destroy the navigation and inundate the country" (p. 18) and "in the spring, the careful husbandman and miller will open every ditch and sluice to get rid of that water which, though at other times a kind friend and faithful servant, is then a dangerous enemy and imperious master. Of course, much of what is now withheld for many days will then be suddenly poured out. The torrents must, therefore, rage with greater fury hereafter than they do in the present day."

Increases in floods as a result of land development and deforestation have remained a controversial subject, but the intensity of argument seems to be abating in the light of accumulated evidence that the effects of land -use on floods are greater small streams than large; and are greater for small floods than large floods. (Hoyt and Langbein, 1955.).

For some of the small streams, such as those that passed under the canal in culverts, forest cutting may indeed have affected floor discharge. According to the experiments in New York (reports by Schneider and Ayer, 1961, p. 59) most of the effect of fores cover on flood peaks is on timing of snowmelt. Partial clearing for example, might reduce flood peaks by desynchronizing snow melt. These hydrologists, who found no effect of forest cover o floods during the growing season, also reported (p. 60) that their results agreed with those of other studies. Modern data would account for no great chan e in the flood regimen of major stream along the Erie Canal, and none seems to have occurred.

SEDIMENT AND ACCELERATED EROSION

Accelerated erosion that might destroy the canal was anticipated. "When the country shall be cultivated, streams swollen by showers will bring down mixed with their waters a proportion of mud, and that, in the stillness of a level canal, will, subside and choak it up" (Commissioners of 1811, p. 18-19). The concerns of the Commissioners were not misplaced; sediment was troublesome, but not disastrous. The erosion of natural earth materials depends on the vegetal cover, rainfall intensity, rock types, and topography. The net affect of these factors is to put upper New York State among those areas of the country where problems of sediment are not especially severe. Any accelerated erosion caused by farming was carried off in the runoff of the streams that drained the region. As an independent canal, it was insulated from these effects. Some of those streams were developed as feeders, and sediment would be diverted with the water. Taking the feeders supplying about 700 cubic feet per second and a sediment concentration of low summer streamflow, as indicated by modern records, to be about 10 parts per million, it appears that some 8,000 cubic yards of sediment were carried into the canal each season, amounting to an average f only 0.002 foot of deposition in a 200-day sea-son. The feeders therefore were not a significant source of deposition. That problem was created rather by the side-hill location of the canal (see g. 7), so advantageous in avoiding other difficulties-such as odds. The canal became a trap for the deposition of the sediment arried by the numerous runners that were led into the canal through the berm bank, because they were too small to be carried under the canal in culverts. Wash and slides along the steep walls of the Mohawk river valley were a continuous problem, as they were along the deep earth cuts in the western division.

WATER QUALITY

The quality of water had great significance to the Commissioners of 1811 who did the original planning. They saw the canal as a potential source of pure water, pointed (p. 21) to that "inex- haustible stream of limpid water which flows out of Lake Erie," and added there "is a strong temptation to use it exclusively until auxiliary supplies can be drawn from reservoirs equally pure. In contrast, buoyancy was the only property of water of interest to the later commissioners during the 19th century operations, and that property was not in question. The operational view of-the canal was economic and not ecologic. The successive annual reports of the commissioners responsible for its operation and maintenance were attentive mainly to traffic, trade, and costs, and had little to say of pollution or sanitary conditions except insofar as garbage or sewage mud may have interfered with navigation. According to recollections of Garrity (1966, p. 15) a covered pail was the toilet. Waste was "easily disposed of by throwing it overboard." Trash thrown into the canal, particularly at cities, became a common problem in the latter part of the 19th century, and open drains carried domestic and industrial wastes into the canal, for the canal was the sink-the low point-for many of the communities built up along its banks. There was therefore a sizable pollution load imposed on the canal (1887 As. Doc. 37, p. 145-156), even if only with respect to that transient population which lived on the canal and who dumped into it directly or indirectly their untreated wastes. An estimate of their pollution load may be made from the average number of boats operating on the canal. Although the number of boats registered during the 1870's numbered between 5,000 and 6,000 (Finch, 1927, p. 857) only about 2,000 were in operation at any one time. Since each operating boat required at least two persons and as many draft animals, and taking the pollution load of a horse or mule as four times that of a person, the population equivalent (p.e.), excluding the resident population, was of the order of 30,000. This population equivalent would impose a daily biochemical oxygen demand (BOD) load on the canal of about 5,000 pounds. This calculation does not include the load imposed by domestic wastes, little of which in the early and mid19th century would have reached the canal, as each home had its own source of water and a privy. Later, however, warehouses, mills, and factories that were built directly along the canal, discharged wastes into the canal. Nevertheless, there were no reports of septic conditions (in distinction to nuisance) which would doubtless have attracted notice even in the 19th century. The canal water, as pointed out in several places, was not stagnant. There was a decided flow through the system, maintained by feeders, bypass weirs, lockages, and leakage. Seepage, the main flow from the canal, amounted to 8 inches per day, and so the residence time of the water in the 4-foot canal (average depth, 3.4 feet) was of the order of 5 days, and about 8 days in the 7-foot canal of the latter half of the 19th century. As calculated previously, the total flow into the 360-mile canal was about 1,900 cfs or about 10,000 million pounds of water per day during the height of its use in the 1870-80's. With water intake saturated with respect to oxygen (10 parts per million of oxygen), the available oxygen supply would be 100,000 pounds per day, many times the oxygen demand imposed by the canal operations. This intake of oxygen to the canal, sufficient, as it turned out, to avoid septic conditions, may be considered to be a byproduct of the inordinate inflow of water required to make up the leakage from the canal. A water tight canal would be a septic canal. . Rafter described the situation at Buffalo, which apparently discharged its sewage effluent into the canal, because as the city authorities claimed, "the Erie Canal along the waterfront had cut off the natural line of drainage [to Lake Erie] of a large portion of the city." Rafter calculated the population equivalent to be about 61,000. On the basis of a dilution of 500 cubic feet per minute (8.3 efs) per thousand population equivalent (p.e.), a canal flow of 50,000 to 60,000 cubic feet per minute, there should be no septic nuisance, although the "sanitary side of the question either as to the effect on health of people living along the line of the canal or on those navigating it, is not taken into account." (P. 192-193.) The problem at the time was rather the necessity to dredge about 15,000 cubic yards of sewage mud each year. Rafter stated that similar but lesser problems also existed at Lockport, Medina, Holley, and other places in the western division. The canal was not a source of drinking water. Each barge carried one or two barrels of drinking water; canal water was used for washing and to water the draft animals. It must have been considered polluted in its later years, as the Act of April 15, 1889 (chapter 141), with reference to the adulteration of food, drugs, and liquors, prohibits (section 3) the sale or transport of ice cut from the canal for any purpose other than cooling of beer unless the ice is contained in a building or cart plainly marked "canal ice." The canal had fish, and fishing was popular. From repeated reports of breaks ascribed to the tunneling activity of muskrats, the canal must have offered a favorable habitat for these animals, which made their home most often in the bank and fed on vegetation growing on the bank and along the canal margin. Swamps and wet, low places were viewed as health hazards and so, in 1833, Jervis omitted construction sites for proposed feeder reservoirs because of the expressed apprehensions of their injurious influence on the health of the adjacent country (1834 As. Doc. 55, p. 61). Blodgett's climatology (1857, p. 477) recorded that "Sources of malaria of artificial origin-reservoirs for canals, and ponds in streams-constantly produces severe intermittent and malignant fevers." Somehow the canal itself aroused no such fears --perhaps because it contained flowing water, although that could not be as evident to the casual observer as it must have been to the straining mule bound for Buffalo. The visual appearance of flow depends -not only on the absolute velocity but on the depth as well. Deep waters do not run still, they only appear to do so.

ESTHETICS AND HUMAN INTEREST

A canal is an improbable alteration of nature. A trough of water is built where not only was there no water before but often in the most unlikely places-very commonly following along the brow of a hill. Yet, as we know, these highly artificial works of the 19th century "sit easily and comfortably into the landscape" (Burton, 1972). The Erie hastened the development of lands that had been only recently open to settlement. The settlers sought not beauty from the canal but cheap transport for their produce and their supplies. Although little, if any, attention was given to esthetics in the construction of the Erie (as distinct from structural workmanship), the intrinsic of the situation introduced elements of a pleasing design. To reduce changes in level and to minimize the need for aqueducts or other stream crossings, the canal followed along a contour, winding up a valley and returning back down on the other side, to avoid a major crossing of the stream in the valley bottom. Cutting along the contour tended to produce an alinement in harmony with the landscape. The 25-percent sinuosity I of the original Erie corresponds to that of mildly meandering rivers (Leopold and Wolman, 1960). Although the canal was straightened in several places in an attempt to eliminate bends, by 1862 the canal length had only been reduced to 350 miles, 13 miles shorter than its original length. From firsthand observation, the British traveler, Basil Hall (1829, p. 127), noted an agreeable degree of curvature that tended to remove the "formality as well as the ditch-like appearance which generally belongs to canals." His impressions were generally favorable. Of his trip along the Mohawk River (p. 119) he wrote "we commanded a range of prospect both up and down of great extent and variety." His countryman, the acerbic Mrs. Frances Trollope, found her travels in 1830 to be a boring experience on crowded packets adding that "From the canal nothing is seen to advantage, and very little is seen at all" (Domestic Manners of the Americans, chap. 32). Scale had something to do with appearance, as Mrs. Trollope also observed (chap. 19),

I strongly felt the truth of an observation I remember to have heard in England, that little rivers were more beautiful the great ones. As features in a landscape, this is assuredly the case. Where the stream is so wide that the object on the opposite shore are indistinct, all beauty is derived from the water itself, whereas when the stream is narrow, it becomes only part of the composition.

The dimensions and scales of the old canals were such that in a sense they fit the terrain-tucked, as it were, into the landscape. Those few canal., of the 19th century that continued in horse- drawn use until such recent times have grown old enough to have become part of the landscape. Amenity and recreational values of these canals seem to, have become treasured assets (Burton, 1972). To preserve them for this use and because of their historical interest, several old canal sites have become State or National parks. The Chesapeake and Ohio Canal, which extends 185 miles from Washington to Cumberland, was built in 1825-30 in response to the success of the Erie, and operated with mule-drawn barges until it was put out of service by floods in 1924. It has been restored in part by the National Park Service. Justice William 0. Douglas had this to say in 1954: "it is a refuge-a long stretch of quiet and peace at the Capitol's back door-a sanctuary where man can commune with God and with Nature." (Quoted in Washington Post, Oct. 1, 1972, p. El). The relatively simple technology available forced the builders into greater conformity with the natural scene than modern builders find necessary. This accommodation to the environment led not only to such pleasant effects as the contoured sinuosity previously noted, but also the use of more natural structural elements such as the stone masonry of the locks and aqueducts. There is powerful esthetic appeal in handicraft. (John Graves, personal commun.)

THE CANAL AND ECOLOGIC RELATIONS

In a recent accounting of the ecological impacts of water projects in California, Hagan and Roberts (1972) list the followin six items with respect to "canals" which might be examined i regard to the Erie Canal, although they are not strictly hydrologi cal and their treatment here is very sketellv.

1. "Interferes with ]arid access across right-of-way." Cutting access was the first "people" 'problem faced by the canal authorities. A liberal policy was adopted to provide bridges across the canal for just about every footpath and cowpath, let alone roads. With clearance of only 7 1/2feet above the water level, these numerous low bridges (averaged 3 to 4 per mile in the eastern or Mohawk division) gave the canal its "Low-Bridge" reputation, and probably hastened its disuse for extensive passenger servi -ce.

2. "Spread pests and disease." Other than to observe that the canal as a vector of pests would be confined between each summit and sag points-the subject is beyond the'hydrological. As a channel for transport of goods and persons, the canal did doubtless aid in the speed with which infectious disease was spread-for example, cholera spread along the canal in 1832 while it was still used for passenger travel (Shaw, 1966, p. 223-224), but it would be no different in this respect from other means of public transport.

3. Effects on fish. Feeder dams across the streams affected the migration of fish-by obstruction and by diversion to a feeder canal that led water as well as fish to the navigation canal. The obstruction effect was only considered a problem where there was commercial fishing as along the Seneca and Oswego Rivers. The engineer's report on the proposed works along those rivers stated that the: fisheries "will be overwhelmed by the process of damming and locking the river" (Canal Laws, v. 1, p. 501), and suggested that some consideration be given to the fishermen displaced. But the main effect of the canal on fish was through the regional interconnections of waterways. For exa mple, De Witt Clinton, in his discourses on the natural history of the region (Clinton, 1820, p. 53-54) stated that "I expect great changes from the junction of the western and eastern waters on the subject of fish. Already have several kinds penetrated the canal at Rome into the Mo hawk River," listing pickerel, black sucker, catfish of the lakes, chub or dace. He added "The canal will bring the western fishes intoeastern waters"

Marsh (1864, p. 116) saw the Erie Canal as 'enhancing variety of fishlife because it enabled the intermixingof freshwater fish and vegetation of the Hudson and the upper lakes. Marsh concluded from this possibility that these two regions "have now more species than before the canal was opened.." Such intermixing was not necessarily advantageous as might be inferred from Marsh's language. The occurrence of two troublesome species of fish, the alewife (Alosa pseudoharengus) and the -sea lamprey (Petromyzon marinus) in Lake Ontario and their subsequent spread into all of the Great Lakes has been attributed to the construction of the Erie Canal and the Welland Canal (first constructed 182433 by Canada between Lake Erie and Lake Ontario-to bypass Niagara Falls possibly to minimize diversion of traffic from Lake Erie to New York by the then new Erie Canal). In an assessment of the aquatic effects of ship canals, Aron and Smith (1971) state "The alewife was first recognized in Lake Ontario in the spring of 1873, when at least three observers reported it was present in abundance. The best evi. dence suggests that it entered through the Erie Canal," (Oswego Canal). Christie (1974, p. 840), who also reviewed the various alternatives - marine relics, inadvertent input during attempts to introduce shad, the Erie Canal, and the St. Lawrence River-could only conclude: "The origin of the alewife in the Great Lakes has not been established with certainty." With respect to the destructive, Lamprey, Aron and Smith conclude: "Although evaluation is not complete, available evidence gives strong support to the possibility that the sea lamprey entered Lake Ontario drainage via the Erie Canal." They observe that the sea lamprey "probably became established first in Cayuga and Seneca Lakes during the mid-1800's and then moved down into Lake Ontario as the alewife did" and conclude that "If it had not been for the Welland Canal these marine invaders and the havoc they caused might have been contained in Lake Ontario." The role of the Erie Canal in introducing the destructive sea lamprey to Lake Ontario seems to be less clear. Aron and Smith indicate that there were no reports of the sea lamprey in Lake Ontario before 1880, but Lawrie (1970), citing Dymond (1922), observed that "Although the sea lamprey (Petromyzon marinus Linnaeus) is generally conceded to be native to Lake Ontario, it is an unwanted and inadvertent introduction to the remaining Great Lakes. Apparently it passed Niagara Falls through the Welland Canal sometime not long before it was first reported from Lake Erie in 1921." Wigley (1959) wrote that "Several lakes in New York, including Cayuga Lake, have supported landlocked populations of sea lampreys for centuries." The hypothesis of a long presence in Lake Ontario as well is given added credence by a record of a breeding population of sea lamprct in Duffins Creek just east of Toronto in May 1835 (Lark, 1973). Either the sea lamprey was in Lake Ontario before the connection with the Hudson River through the Erie and Oswego Canals (the latter completed in 1829), or it penetrated the 150 miles of canal and invaded the lake in the relatively brief period of time between 1829 and 1835. If the sea lamprey did penetrate the Erie Canal rapidly and by an early date, why did they not continue on to Lake Erie by the same means? Perhaps they did. As already noted, velocities in the canal were low and the Lockport combines would seem to have been no more an obstacle than the locks on the Welland Canal. In the absence of direct evidence of the presence of the sea lamprey either in the canal system or in Lake Ontario prior to the opening of the Erie Canal, the possible invasion through the canal remains a conjectural though viable alternative to the possibility of a pre--canaj presence in Lake Ontario. There were other migrants. For example, Hubbs and Bailey (1938, p. 28) state that "The small-mouthed bass is known to have invaded the Hudson valley together with the large-mouth after the opening of the Erie Canal about 1825." Trautwine (1957) includes several citations of 19th cen- tury statements of the role of the canals on the migration of fish, but the association is usually based on inference rather than on direct evidence. With reference to migration, he noted further (p. 184) the possibility that the presence of a fish specie may be overlooked until a cyclic peak of abundance brings them to notice.

The 19th century fish record seems no more complete than the hydrologic. Taken together with a complex ecosystem, the haphazard record obscures conclusions as to the extent and manner in which the canal was implicated in the spread of undesirable fish species. 4. "Results in loss of wildlife." No mention of such loss in the 'record; however, the canal provided a favorable habitat for water-related mammals-for example, muskrats. (See Clinton, 1820, p. 43-45.) 5. "Creates safety hazard for children."-unfenced. 6. "Provides opportunities for parks and recreation where de- veloped." Numerous sections along the abandoned canal have been developed for these purposes.

EFFECTS AFTER ABANDONMENT

When canal reaches were abandoned as a result of relocation during the enlargements of 1836-62, or 1905-17, most were simply drained to become open ditches, although some sections were refilled to serve as ponds for fish culture (Titcomb, 1920). In the absence of an organized plan for disposal or protection (Supt. of Public Works, 1916, p. 19-20) the vacated lands were adapted to local purposes. Their linear character made travel the major use as before. As a minimum, the towpaths have been used as footpaths or as local roads. The old 40 x 4-foot canal winding along the drumlins in the lake district, abandoned for the 7O X 7-foot enlargement (see fig. 5), became roadways, usually starting with the towpath and gradually widened by filling in the canal until the road occupied nearly the whole right-of-way. Since much of the 70 x 7-foot enlargement followed the same general alinement as the older canal, little of that can be found. Large-scale abandonment of the 70 x 7-foot canal occurred during the 1905-17 enlargement (see section "New York Canals in the 19th Century"). Although over the years the abandoned 70 x 7-foot canal became subject to many changes, about 100 miles of open ditch between Rochester and Albany still appear on the topographic maps. (West of Rochester the existing 1905-17 enlargement occupies the same alinement as the earlier sections.) In cities the open ditch was filled to become city streets, and a few towns made the old canal .site into parks. Most of the open mileage contains the marks of cutting, filling, or dumping so that there are relatively few sections of abandoned canal that are sufficiently distant from habitation and roadways to have regressed naturally. Several of these sections (including one of the 40 x 4-foot canal) were examined in 1974 to see the kinds of changes that took place.

As shown on figure 11, changes in cross sections from natural causes were small when compared with the design section. In fact, it is surmised that the fill along the bottom edges and the filleting of the corners may have taken place by sedimentation while the canal was in use. (See 1888 As. Doc. 25, p. 63.) Alternatively, from the evidence, one might question whether some sections as built conformed to the design sections as noted by Whitford (1906, p. 1037-1043). The time for active erosion after the canal was drained must have been short. Bank wash could occur only for a few years as rapid growth of a succession of weeds, brush, and trees in the moist soil gave protection to the side slopes. The bank rip-rap of 10-12-inch boulders would also serve to lessen erosion, although many of these were generally found to have moved downhill, probably as a result of frost action. As seen today, the open ditch is heavily overgrown by brush and trees, such as willow and ash, and where there is standing water the bed contains dense growth of cattails and rushes.

There is a stark contrast between a full and flowing canal and an abandoned open ditch. The former is a source of water flowing, in part, into the ground, the latter a sump for surface drainage and for outseepage from the ground. With a few exceptions, the open ditch contains near stagnant water, about 12 inches or less in depth, derived from seepage of ground water through the banks or from drainage of rain water down the side slopes. The ditch itself, being nearly level and being at an elevation above that of the streams that cross or parallel it, has not been captured by the active river system, and there is no large-scale erosion of the ditch such as might have occurred by river erosion. Even though some sections, especially in the Montezuma swamp, are put to use to convey water drained from agricultural lands, velocities are too low to erode the banks or bed. Some surface pondage was noted back of the banks where the canal was built away from the side hill, such as where the canal alinement was straightened. The canal was built as a shallow ditch in or upon till or alluvium; major aquifers were not cut and the scale of operations did not constitute an irreversible change upon the hydrology. Al- though far from an asset, the present condition of the abandoned ditch falls short of being a hydrologic threat to the well being of the contiguous lands.

SUMMARY

Today's concern with "environmental impact" centers upon the external effects of proposed projects. The promoters and planners of the Erie Canal also were heedful of environmental effects, but centered their attention on those that might effect the proposed canal. For example, the record repeatedly details their apprehensions about the forest cutting and farming to be expected as a result of the canal, but aimed at the possibility that such changes would affect streamflow and erosion in ways that would damage canal operations. The flow of rivers did not decrease as originally feared. The planners feared that land use would increase the

intensity of flooding and so endanger the canal. Floods were indeed a serious problem, but not for the anticipated reason. Although "bottoming out" was necessary to remove sediment carried in by the feeders or brought in by bank wash, sediment was not generally a major difficulty.

The dissolved oxygen brought into the canal with the feeders was sufficient to inhibit the development of septic conditions despite the pollution load imposed by canal operations and by towns or cities along the way. The great amount of water inflow required because of the leakage from the canal was an asset in maintaining a flow of oxygen through the canal.

Nevertheless, there were many external effects of the canal. River flow and ground water were affected by the canal. Stream flow was reduced as large quantities of water were diverted from the rivers into the canal. The canal was built above the regional water table and therefore the canal acted as a linear source of recharge to the ground, deriving water from the upland streams. In addition, there were significant effects on migration of fish. The Erie Canal may be implicated in the spread into the Great Lakes of the sea lamprey and the alewife, two troublesome species of fish.

Looking only at the hydrology, the canal was by no means an environmental disaster. The external effects were neither systematically adverse nor systematically beneficial. For example, consider water flow. The diversions from the rivers used to feed the canal were frequently contested by mill owners, but the seepage of that water to the streams below the canal through the ground-water system would tend to increase the dry weather flow of those streams and to that extent would be an asset to water users downstream. Land development induced by the canal was a factor of great economic benefit. Flood backwater at culverts was a source of relatively minor land damage. The operators of the canal could cope with these effects on a project of the scale of the Erie Canal. Needed corrective actions were plainly evident and could be taken at the time.

Because the early canals were constructed of local materials, and were subject to hazards as well as an uncertain supply of water, the planners necessarily had a weather-eye for the unknown relations between the terrain and their proposed works. In the building, and later in the maintenance and repair that was required by deficiencies in design, the responsibilities to make sure the scheme worked passed to the construction engineer. Predicted external effects that did not materialize could be ignored by the busy, practical engineer. The environmental projections that were so prominent in the planning reports for the Erie Canal seemed to be the last for the century. Thus, Jervis, who had built and maintained much of the Erie Canal and many other; as well as rail lines, had nothing to say of environmental effects of engineering works in his memoir (1877).

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