74 



water the average height for the year was 6.9 feet— a slight increase over the 

 preceding year. There was thus p"esent the somewhat unusual condition of 

 long- continued high water during the first half of the year followed by an un- 

 interrupted period of unusually low water in the second half, the change 

 from the one to the other being quite abrupt. Under these circumstances the 

 vee-etation was largely removed or its excesxsive growth prevented. The contrast 

 between high- and low-^vater conditions in the station field is well shown by 

 several of the plates appended to this report.* This long- continued low wa- 

 ter worked marked changes in the topography of the bottomlands adjac^^nt to 

 Havana. Phelps Laket dried up earlier than it did the preceding 3'ear, 

 Thompson's Lake showed a marked diminution, principally at the northern 

 and southern ends, long stretches of soft mud or matted vetetation in which 

 dead fish were abundant being exposed. This mud, after a few weeks ex- 

 posure, hardened and cracked open to a depth of a foot or eighteen inches, 

 and a growth of shore grass began to spring lap on it. Quiver lake, espec- 

 ially along the west shore and in the region known as Dogfish lake, was con- 

 siderably reduced in area, and in the absence of anj- considerable amount of 

 vegetation its depth was decreased more than usual. Flag lake, which in 

 most years is a marsh with one to four feet of water filled with rushes, arrow 

 leaves, water smartweed, water-lilies, and the lotus, dried up early and a 

 wagon road was established across its bed. Havana lake, the expanse of the 

 river above the mouth of Spoon river, presented the unusual appearance of 

 a narrow river channel flanked on either side by a broad mud bank. The 

 filling in and extension of these banks by the deposit of silt during recent 

 years has been very marked, and is followed by an extension of the swamp 

 willows oyer the risirg banks. 



In a general way the hydrological conditions of 1898 resembled those of 

 1897. The rise of the river began in Januai'y and continued through the win- 

 ter, culminating April 2 at eighteen feet, a point equaled or exceeded but 

 twice since 1879, at which time records were begun at the Govei'ument dam 

 at Copperas Creek, eighteen miles above the lof^ation of the station. As in 

 1897, the high water continued during the early summer, dropping rapidly in 

 Ausust to the minimum stage. It did not, however, reach the extreme con- 

 dition of the previous year, several minor fluctuations having occurred at 

 frequent intervals during the fall months. The reduction in the acquatic 

 vegetation begun in the previous year has continued. The increased activity 

 in the fishing industry has also contributed largely to the removal of the veg- 

 etation from the lakes and the river on the fishing grounds, so that the river 

 is now practically free from vegetation, as is also the main bodj' of Quiver 

 lake and almost the whole of Thompson's lake, only a restricted area at the 

 southern end retaining its former condition. 



In previous years the field headquarters of the station have been on Quiver, 

 lake, either at Foster's Lauding or at tiie Indian mounds. In the fall of 

 1896 the new laboratory boat was brought down to town and was stationed at 

 the public lauding along the river front. This location has been retained 

 during the last two years with the exception of a week in August, 1898. when 

 the boat was moved up to the Twin Mounds during some continued work up- 

 on the plankton and gas analyses in the Illinois river near that point. The 

 advantages of a location at town are the saving of the time required for tran- 

 sit to and from headquarters in the field and the expense of running the 

 launch on these trips, and the ready access to the station from living quar- 

 ters at all times, while the distance from the collecting grounds is not greatly 

 increased. Some disadvantages attend this location. The sheltered situation 

 and the close proximity to the sand bluif increase the heat in the boat during 

 the hot days in summer, and the nearness to the steamboat landing greatlj* in- 

 creases the risk of damage to the boats and lauuch by the disturbance in the 

 water caused by incoming and outgoing' steamboats. Ropes and cavils are 

 frequently broken, and boats are torn loose bj' the swells which follow iu the 

 wake of the larger steamers. On three separate occasions a steamboat in the 



*For these localities see Plate I. 



tComparc I'lates III. and IV.. and V. and VI. For differences with respect to mid-suin- 

 mer vegetation at similar stage of water, see Plates Vll. and VIII. 



