environmental engineering case study short answer problemsazheng
O C T O B E R 2 0 1 0 C i v i l E n g i n e e r i n g 
Linking the Lakes: The Lake Washington Ship Canal
C IVIL ENGINEERS usually make decisions that are quantitative and require data and mathemati-cal prowess. Other decisions, however, are not so straightforward. In some instances the civil engi- neer must seek to gauge the effect of his or her project not just on the community but on the region, the state, and even the country as a whole. Such was the case more than a century ago when the citizens of Seattle asked the U.S. Army Corps of En- gineers to construct a canal that would link Lake Washing- ton to Puget Sound. In performing this task, such prominent engineers as Hiram M. Chittenden and James B. Cavanaugh were faced with a number of formidable challenges, among them where to construct the canal, whether to lower or raise the levels of the lakes involved, and how to link salt water with freshwater without destroying an entire ecosystem.
Seattle was settled on the eastern shore of Elliott Bay, an arm of Puget Sound. Located north of the bay are, from west to east, Shilshole Bay and Salmon Bay, both saltwater, and Lake Union and Lake Washington, both freshwater. Lake Washington is a long, ribbonlike lake that forms Seattle’s eastern border.
As early as 1854 a settler by the name of Thomas Mercer voiced the need for a canal that would link Lake Washington to the sound. Several years later John McGilvra, a local real estate investor, mentioned how a canal would help improve lakeside properties, and H.L. Pike unsuccessfully attempted to excavate a canal through the narrow ridge separating Lake Union from Lake Washington.
After the Civil War, the U.S. Army Corps of Engineers be- lieved that Lake Washington would be an appropriate place for a naval station, a station that would require a link to Puget Sound. In late 1871 Lieutenant Thomas H. Handbury sub- mitted a proposal to spend $4.7 million to excavate a channel that would connect Lake Washington to Lake Union. He also proposed constructing a channel between the south end of
Lake Union and Elliott Bay.
The government soon scrapped the project, however, in favor of a base on Sinclair Inlet at the town of Bremerton, southeast of Bainbridge Island.
In 1881 a number of Seattle investors founded the Wash- ington Improvement Company to fund the construction of a canal between Lake Washington and Lake Union. Four years later a workforce of Chinese immigrants excavated a 16 ft wide waterway between the two lakes. Named the Portage Canal, it featured two locks and was primarily used to trans- port logs to sawmills on Lake Union.
After the fi re in Seattle that destroyed most of the business district in 1889, the city’s sawmill owners relocated north to the small community of Ballard, located along the banks of Salmon Bay. The booming lumber industry, coupled with the phenomenal growth in population in Seattle in the 1890s, increased the demand for a canal extending to Puget Sound.
The demand did not fall on deaf ears. In 1891, two years af- ter Washington had become a state, the Corps formed a board to study fi ve possible routes for a canal that would connect Lake Washington to the sound. The fi rst followed Black Creek, the natural outlet of Lake Washington. The creek ran southward until it encountered the Duwamish River, which from there
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History Lesson fl owed northwest through a valley and into Elliott Bay. The second and third options involved direct links between Lake Union and Elliott Bay. The fourth and fi fth options, however, proposed linking Lake Union to Salmon Bay and then build- ing a second canal either west to Shilshole Bay or south to Smith Cove, located on the northwest side of Elliott Bay.
The board determined that the route along Black Creek and the Duwamish River would be impracticable. It also found the land between Lake Union and Elliott Bay to be too expen- sive, leaving the Salmon Bay options as the most feasible. The board estimated that a canal would cost $3.5 million if it ex- tended to Smith Cove and $2.9 million if it went to Shilshole Bay. Despite this signifi cant difference in cost, the Smith Cove route was preferred because it was closer to Seattle’s harbor and would, if necessary, be easier to defend militarily.
Seattle’s residents greeted the board’s report enthusias- tically, but those outside the city opposed the plan, nick- naming it Seattle’s Ditch. As a result of its cost and limited popularity, the Corps decided to omit the canal from its rec- ommended projects for 1892 and to leave its construction, as well as its funding, to local entities.
Eugene Semple, a former governor of Wash- ington Territory, believed that a privately constructed ca- nal was possible but not in the form rec- ommended by
the Corps. He was of the opinion that a canal con-
structed at the mouth of the Duwamish River could be ex-
tended through a man-made cut in a ridge referred to locally as Beacon
Hill. From there it would run through Rainier Valley and another ridge before
reaching Lake Washington. Eager to establish his credibility and attract investors,
Semple engaged the services of Captain Thomas Symons of the Corps district based in Portland, Oregon. Even though
the Corps was not offi cially involved, Symons believed it per- missible to assume the role of consultant. He drafted a report of his opinions about the practicability of constructing a ca- nal according to Semple’s design. Believing he was working in the best interests of the public, Semple presented Symons’s report as an offi cial endorsement by the Corps and used it to entice backers. By 1893 he had secured authorization from the state legislature, and the following year he succeeded in convincing eastern investors to fund the project.
Meanwhile, Ballard residents and industry owners decid- ed to ask for federal funding for their own canal. In 1894, as Semple’s project took shape, the U.S. Congress approved the formation of a committee to consider a canal linking Lake Union to the sound and assigned Symons to chair the com- mittee. The business owners called attention to the fact that the captain was also a consultant for Semple’s canal, nick- named the South Canal, and saw his involvement in the new- ly proposed “North Canal” as a confl ict of interest. The Corps transferred Symons to Buffalo, New York, in 1895.
Before being transferred, however, Symons complet-
ed a survey of the North Canal. He confi ned the survey to the Shilshole Bay location proposed in the 1891 survey. His report also suggested a dam and lock at the mouth of Salmon Bay. A second lock would be placed at Lake Washington so that the lake could retain its el- evation, which was approximately 7 ft higher than Lake Union. The estimated cost of the project, as of June 1895, was an unre- alistically low $1.4 million.
The move by Congress in 1894 also required that King County make the necessary land purchases for the canal’s right- of-way. The county offi cials, however, experienced diffi culty lo- cating land owners and completing the necessary legal steps to
HIRAM M. CHITTENDEN’S 1907 MAP OF THE PROPOSED CANAL ALIGNMENT CONNECTING PUGET SOUND WITH LAKE UNION AND LAKE WASHINGTON
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procure the lands, and in many cases the parcels purchased were overpriced. It was not until June 1900 that the county was able to turn the right-of-way over to the federal government.
Despite the diffi culties in securing the right-of-way, Cap- tain Harry Taylor, who was named head of the newly estab- lished Corps district headquartered in Seattle, suggested that the Smith Cove terminus be reconsidered because of a drop in land prices. As a result, the U.S. Department of War changed the canal location, and once again the county set about ac- quiring the right-of-way.
The seemingly last-minute change did not please the
owners of the Great Northern Railway Company, for they had property interests along that route. In fact, the rail company threatened to abandon Seattle altogether if the canal was constructed at Smith Cove. Faced with this ultimatum, the De- partment of War reverted to the Shilshole Bay ter- minus, probably to the frustration of the county offi cials attempting to procure the right-of-way for the Smith Cove route.
Another obstacle cropped up at the turn of the century. During the previous decade commerce to and from Seattle and the size of the vessels traveling through Puget Sound had grown, and the former specifi cations for the locks had become inadequate. Taylor proposed a new plan for locks that would be approximately 800 ft long and 100 ft wide and would ac- commodate vessels with a maximum draft of 30 ft.
In the meantime Semple had been working on excavating the South Canal through Beacon Hill. Using high-pressure hoses, he washed away the soil, and a gravity fl ume carried it to the tidal fl ats below. Although this practice was successful at fi rst, it would not be effective for very long because the an-
gle of the fl ume would be reduced as the hill itself was exca- vated. Furthermore, the high-pressure hoses and fl ume were useless against large boulders.
It seemed that Semple understood these diffi culties but counted on the fact that the North Canal’s cost would spiral out of control. Then, he hoped, the government would cease construction there and fund his project.
Semple was right on one count. The estimated cost of the North Canal had been woefully low. Major John Millis, the Corps’s new district engineer, stated in 1901 that the new locks would cost approximately four times as much as the original
ones and that the project’s overall price tag would be a prohibitive $6.3 million.
This was Semple’s chance. He of- fered to sell his canal to the government upon completion for just $2 million. Advocates for both the North Canal and the South Canal approached Con- gress, which commissioned another study by the Corps to determine the feasibility of the two canals.
The board of Corps offi cials visit- ed Seattle in August and November of 1901. To Semple’s dismay, it dismissed the South Canal almost immediately because of the height of Beacon Hill and the other ridge. The board con- cluded that fi ve times as much material would have to be removed to construct the South Canal than to build the other. It also determined that the South Canal would cut through nearby streets, water mains, and railroad tracks.
The North Canal, according to the board, was feasible from an engineer- ing standpoint. Nevertheless, the board raised another concern. It questioned
whether the commercial needs of Seattle would jus- tify the cost of the canal’s construction, operation, and maintenance. Because of the board’s concerns, the Corps’s offi cial position became that no canal of any kind could be justifi ed by economic need.
Semple either was unwilling to give up on his investment or was as unaware as his Dickensian name implied. He attempted to continue with his
canal by trying to woo potential investors. Nevertheless, the disparaging comments about the South Canal in the board’s report discouraged potential backers. In May 1904 the city forced Semple to halt operations.
It was under these bleak conditions that Major Hiram M. Chittenden replaced Millis as the district engineer in 1906. A native of western New York, Chittenden was an intelligent and enthusiastic individual who had abandoned a career in law to join the Corps. Prior to his assignment in Seattle, he had declined the superintendency of Yellowstone National Park.
Upon his arrival, Chittenden believed that the completion of the Lake Washington Ship Canal, as it came to be named, would be his highest priority. Because of a nervous condition
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that often left him incapacitated, he believed this would be his fi nal engineering project, and he wanted it to be a success.
Chittenden saw that he would have to work quickly, how- ever. A prominent Seattle investor by the name of James A. Moore was negotiating with the county to construct a wood- en lock at the eastern end of Salmon Bay. Chittenden had no faith in Moore’s engineering acumen and believed that the inadequately constructed wooden lock would eventually be turned over to the Corps, which would then have to maintain it. He later stated that the lock “could never have been built on a basis of safety and it would surely have collapsed sooner or later and precipitated Lake Wash- ington into Puget Sound.” Never- theless, because the Corps had no plans to construct any locks at that time, Chittenden could not legally halt construction of the lock.
Chittenden’s hands may have been tied legally, but he was will- ing to investigate other strategies. He befriended local leaders and took them for rides on the lakes in his own boat. It was on these trips that Chittenden would express his doubts about Moore’s project, or as he put it, he “spread a leaven of doubt as to the whole scheme and this continued to develop until it overthrew the Moore project.”
Chittenden’s tactics proved ef- fective. In 1907 the newly formed Lake Washington Canal Associa- tion endorsed new terms for fund- ing the canal’s construction by the Corps. Chittenden himself drafted the terms and convinced Congress that the previous assessment ques- tioning the commercial justifi cation for the ca- nal was ill founded. On the basis of a study of his own that he completed by the end of 1907, he concluded that the project was fi nancially feasible. Without local support, Moore knew he was beaten, and he transferred his rights to construct the lock to the Lake Washington Ca- nal Association.
Chittenden quickly formed new plans for the canal. Believing that a single lock at Salmon Bay would be in- suffi cient and uneconomical, he suggested the construction of two locks: one for small steamers, tugboats, and recreational boats and one for large merchant ships. The small lock was to be 150 by 30 by 16 ft; the larger, 825 by 80 by 36 ft. Both would be capable of raising vessels approximately 20 ft from sea level to the elevation of Lake Union. He also omitted the construction of a lock at the eastern terminus of the canal so that the level of Lake Washington could be lowered by 9 ft to the same elevation as Lake Union.
By 1908 Chittenden’s revised plans for the canal had been approved. Unfortunately, his health left him bedridden, and
he underwent painful shock treatments. In December 1909 he retired from the Corps.
Chittenden may have been gone, but his plans moved forward. In early 1910 the state legislature appropriated $250,000 for the project. The fi rst contract was to excavate a canal linking Lake Washington and Lake Union. The new canal would be located just north of the smaller Portage Ca- nal, which had been constructed by Seattle investors nearly 30 years earlier.
Major James B. Cavanaugh was appointed the district engineer for Seattle in 1911 and was placed in charge of the
project. The following year workers excavated nearly 250,000 cu yd of material, and by early 1913 the fi rst concrete was poured into forms for the lock walls.
To keep salt water carried in the locks from infi ltrating Lake Union and Lake Washington and destroy- ing the ecosystem, a saltwater basin 200 ft long and 200 ft wide was con- structed above the locks. The heavier salt water settling in the basin was to be carried through a drainage pipe with a cross section of 30 sq ft to an adjacent spillway dam, and from there it would exit approximately 4 ft below the mean high tide. The fl ow through the pipe was continu- ous at a rate of 100 to 3,200 cfs.
The locks were completed on Au- gust 3, 1916, three weeks before the new canal between Lake Union and Lake Washington was completed. By the end of 1916, more than 7,500 vessels, approximately 12,000 pas- sengers, and 201,000 tons of freight
had passed through the locks. The offi cial dedi- cation of the project took place on July 4, 1917, despite the fact that some dredging and bank re- vetment work was still needed. The project also included a 10-step fi sh ladder to facilitate the mi- gration of salmon and trout. The total cost of the undertaking was approximately $3.5 million.
The locks were later named the Hiram M. Chittenden Locks, after the engineer who
worked so tirelessly to make them possible. Now used mostly for recreational boats and commercial fi shing ves-
sels, the locks and canal are still in operation. The waterway is a monu- ment to the history of canal construc- tion as well as to the vision guiding the decisions of the civil engineer. The Lake Washington Ship Canal is listed in the National Register of Historic Plac- es and has been recognized in ASCE’s Historic Civil Engineering Landmark Program. —BRETT HANSEN
O C T O B E R 2 0 1 0 C i v i l E n g i n e e r i n g 
Chittenden suggest- ed that two locks be constructed—one for small steamers, tug-
boats, and recreation- al boats and one for
large merchant ships.
Major Hiram M. Chitten- den was from western
New York. Intelligent and enthusiastic, he suffered from poor health and for this reason was intent on completing the Lake Washington Ship Canal.
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Artificial Eutrophication of Lake Washington’
W. T. EDMONDSON, G. C. ANDERSON Department of Zoology, University of Washington, Seattle
AND DONALD R. PETERSON Washington Pollution Control Commission, Olympia
Lake Washington has been receiving increasing amounts of treated sewage, and appears to be responding by changes in kind and quantity of biota. In 1933 and 1950 the dominant phytoplankton organisms were Anabaena and various diatoms and dinoflagellates, but in 1955, apparently for the first time, there was a large population of the blue-green alga, Oscillatoria rubescens, a species which makes nuisance blooms in a number of lakes. A great increase in the hypolimnetic oxygen deficit is taken as evidence of increased productivity; the deficit was 1.18 mg/cm2/month in 1933, 2.00 in 1950, and 3.13 in 1955. There is a fairly close relation between the decrease of oxygen and increase in phosphate concentration in the hypolimnion between measurements, a much less close relation with the chlorophyll
concentration in the epilimnion.
Many lakes have been made productive by enrichment with domestic sewage or other drainage rich in nutrients. Such enrichment can, over a period of years, greatly modify the character of a lake, converting an oligotrophic lake to a con- dition of eutrophy, and resulting in the annual production of large populations of algae, usually dominated by the Myxophy- ceae (blue-green algae). Such populations or “blooms” are notorious nuisances, but these situations are of great interest to limnolo- gists for the insight they permit into the productive processes of lakes. Several such cases were reviewed by Hasler (1947). One of the best studied examples is Zurichsee, Switzerland, which changed in a relatively short time from an oligotrophic lake, with trout, to a eutrophic lake which
1 Some of the data discussed were obtained with the aid of the State of Washington Research Fund in Biology and Medicine (Initiative 171). We are indebted to Dr. Richard Fleming of the Depart- ment of Oceanography for permission to use un- published data, and data in technical reports obtained by the Department of Oceanography with support by contract N8onr-520/111 with the Office of Naval Research. We acknowledge with thanks the help of Dr. Francis Drouet in identify- ing algae and providing information about distri- bution, and of Mr. Rufus Kiser in giving informa- tion about the occurrence of Bosmina in Lake Washington.
produces blooms of Oscillatoria rubescens and no longer supports trout. Late in the 19th century the summer phytoplankton populations rather abruptly assumed bloom proportions, and about a decade later the cladoceran Bosmina longirostris replaced B . coregoni. Interestingly, fossil evidence shows that Linsley Pond had the same change of Bosmina species during its de- velopment at the time it was becoming eutrophic (Deevey 1942).
0. rubescens appears to be an important nuisance in the polluted lakes of Switzer- land, and it has been reported in large populations in many lakes in the United States. It was of considerable interest, therefore, to observe that 0. rubescens oc- curred in great quantity in Lake Washing- ton during the spring and summer of 1955, probably for the first time. Lake Washing- ton has been receiving treated sewage at an accelerating rate (Fig. 1A). According to figures on the relation of human population to the phosphorus content of sewage-treat- ment-plant effluent given in Sawyer’s detailed paper (1947), and the population associated with the Lake Washington effluent recorded in Fig. lA, the annual increment of phosphorus to the lake from this source in 1955 would be 37,000 kg, enough to give an average concentration of 0.0132 mg/l (0.426 pg at/l). Nitrogen
48 EDMONDSON, ANDERSON AND PETERSON
I 1933 TIME 19ko 19155
FIG. 1. A. Daily capacity of the sewage treat- ment plants emptying effluent into Lake Washing- ton, 1932-1955. Not included is the amount of untreated sewage and drainage from septic tanks. B. Oxygen deficit below 20 meters for the period 20 June-20 August each year, with the exceptions noted in text. The deficit is given on the basis of a 30-day month.
would be 5 times this on a weight basis. Although a detailed budget of sources of nutrients has not been made, it seems very likely that the observed changes in the lake can be attributed to the increased sewage. It seems possible that if enrichment con- tinues the lake may develop serious blooms of the sort experienced in so many other lakes that have similarly been enriched by urban development.
The purpose of the present paper is to describe some of the changes that have taken place since 1933, as far as they are now known. The lake has been studied a number of times. Although the lake was sampled on 9 August, 1913 (Kemmerer, Bovard and Boorman 1923), the earliest detailed work was done by Scheffer and Robinson (1939),
Scheffer (1936), and Robinson (1938), including semi-quantitative estimates of plankton populations and analyses of oxygen, phosphorus and nitrogen. Comita (1953) and Anderson (1954) obtained quantitative data on copepods, phytoplank- ton (including chlorophyll), and some chemical features. The Pollution Control Commission of the State of Washington has presented data on pollution during 1952, and the results of a widespread sampling of surface chemical conditions throughout the year 1952-1953 (Peterson et al 1952, Peterson 1955). The University of Wash- ington Department of Oceanography, in connection with a study of salt water in- trusion into the lake, obtained data on oxygen, salinity and temperature during the years 1950-1955 (Seckel and Rattray 1953, Collias and Seckel 1954, Rattray, Seckel and Barnes 1954, and unpublished). Dur- ing the current summer the present authors took data on oxygen, phosphate, temper- ature and phytoplankton. The most de- tailed biological information exists for 1933, 1950 and 1955.
The summer standing crop of phyto- plankton has increased significantly (Table 1). Except for a strong pulse of Peridinium in late August 1950, the 1950 values are consistently much smaller than for cor-
TABLE 1. Phytoplankton population volume in Lake Washington, calculated on the basis of
cell number and cell volume Multiply the values shown by 103 to get #/ml.
Weighted means are given for the period July- August. Epilimnion only.
Phyto- Oscillatoria Oscilla- phormi- Aphanieo-
plankton rubescens toria
agardhi diunt sp. ~o~me~~ae
13 May 24 June 21 July 4 Aug 21 Aug 1 Sept 15 Sept
1 July 14 July 18 Aug 22 Sept
2,140 794 211 219
3,069 567 762 935
a4 2 16 8 30 4 5 2 3 0 9 13 1 105
2,895 1,407 1;755 1,314 1,725
2,783 0 1 893 0 8 397 0 610 255 0 125
0 493 727
ARTIFICIAL EUTROPHICATION OF LAKE WASHINGTON 49
responding times in the summer of 1955. On the basis of chlorophyll content and Secchi disc transparency, it may be stated that the phytoplankton population was somewhat denser on 14 June 1955 than on 1 July, but material is not available for an actual census.
The difference in plankton is indicated further by the fact that the mean summer Secchi disc transparency in 1950 was 3.5 meters (range 3.24.0) and only 2.3 (range 1.7-2.8) in 1955. In 1955 the water looked murky and had a striking, somewhat rusty color, due to the pigment in Oscillatoria rubescens that gives the species its name.
Qualitatively the plankton was rather different from one period of investigation to another. In 1933 the major components of the summer plankton included Anabaena lemmermanni and a number of diatoms. Oscillatoria sp. and Phormidium sp. were rare at all times. In 1950 the largest popu- lations were due to diatoms in the spring, and dinoflagellates in the late summer. Species of Anabaena, other than lemmer- manni, occurred but did not become abundant. Phormidium sp. had a pulse in mid-September, and Oscillatoria agardhi formed a relatively large population in February, but 0. rubescens did not occur. In 1950 the greatest relative abundance of blue-green algae occurred on 15 September when 52 % of the plankton volume was composed of Aphanocapsa and Phormidium cells. The greatest absolute quantity of blue-green algae that year occurred on I1 February when there were 311 X IO3 pa/l, averaged for the whole lake, of Oscil- latoria agardhi, amounting to 34% of the total crop. The situation in 1955 was qualitatively very different, for of the maximum counted crop, on 1 July, 96 % was composed of Oscillatoria rubescens. In 1933 the lake contained Bosmina Zongi- spina Leydig ( = B. coregoni longispina), the earlier form in the succession observed in Ziirichsee and Linsley Pond. B. Zongiros- tris was observed in the lake as early as 1940. Thus, the change of Bosmina oc- curred before the appearance of OscilZatoria rubescens in Lake Washington, reversing the sequence in Ziirichsee.
An interesting ecological problem exists in connection with the two morphologically similar species of Oscillatoria that have occurred in Lake Washington, 0. ubardhi, and 0. rubescens. The replacement of one species by another may imply a distinct, b& perhaps subtle, difference in ecological requirements. 0. agardhi has been observed to form very dense populations in a thin layer in the upper part of the hypolimnion of Hall Lake, Washington, during the summer, and to appear at the surface in moderate quantities only during the eariy fall (Anderson 1954). In Lake Washington it was abundant only during isothermal conditions, and was about twice as abundant near the bottom of the lake as at the top on the date of the maximum observed p~pu- lations. 0. rubescens has frequently been reported in abundance during the winter, although it may occur in great quantity during the summer in the hypolimnion of some lakes (e.g., Findenegg 1943, Thomas and Msrki 1949). Nevertheless, it was abundant in the surface waters of Lake Washington during the summer at t’empera- tures up to 2O”C, although the large popu- lation on 14 June occurred at a temperature of 15”. It has been shown that in Ziirichsee, 0. rubescens adjusts its level to that- at which a low light intensity exists (Thomti 1950). Apparently in some lakes this depth is in the epilimnion, in others below it. In the former case, the population is kept dis- tributed through the epilimnion by mixing.
In the absence of direct determinations ~8 photosynthetic rate and of hypolimnetic carbon dioxide accumulation, we have used the oxygen deficit as a measure of pro- ductivity (Hutchinson 1938, Ohle 1952). Originally, the deficit was considered simply as the quantity of oxygen necessary to resaturate the hypolimnion at the end of summer stratification. Obviously, the mag- nitude of the deficit will be related …