A Contribution to the Characterization of Illinois Reference/Background Conditions for Setting Nitrogen Criteria for Surface Waters in Illinois

ii The pre-1900 condition along the Lower Illinois River by Quiver Lake in the summer. This three-mile long lake running parallel to the Illinois River was fed in part by the Spoon River, the most pristine 19th century river in the Illinois River Basin, and in summer by springs issuing from sand at the base of a bluff along its eastern shore. Quiver Lake illustrates what visitors to the Lower Illinois River in its undisturbed state had seen: “The aquatic environment...impresses the visiting biologist who for the first time traverses its river, lakes, and marshes, as one of exceedingly abundant vegetation, indeed almost tropical in its luxuriance...he will find acres upon acres of ‘moss,’ as the fishermen call it— a dense mat of mingled Ceratophyllum and Elodea choking many of the lakes from shore to shore, and rendering travel by boat a tedious and laborious process.... The carpets of Lemnaceae will be surprising, and the gigantic growths of the semiaquatic Polygonums will furnish evidence of the fertility of their environment” (Kofoid, 1903, pp. 236-237). Pictured from the shore, the surface of Quiver Lake is almost entirely weed choked, permitting reflection from only a small fraction of the lake surface. If an aerial photograph had been taken, as with the river and lakes of Figure 23 with their minor weed coverage, little open water would have been seen in Quiver Lake. P. xi, lines 1-5, change to: " ...Illinois River in 1894-1899 was reported to be 3.68 mg N/l and additional large amounts of nitrogen not measured were stored in the then-luxuriant growth of aquatic (and other) vegetation and transported in copious, albeit, unmeasured amounts of organic debris. In view of the many uncertain adjustments that have to be made in comparing these historical data with recent data, we can not conclude that the Lower Illinois River was any more N rich in the 1990s than it was in the 1890s. " P.9, line 15, add: " Travelling further up the Illinois river, Schoolcraft described the water of Lake Peoria as 'beautifully clear', the Vermilion River as 'a fine clear stream', the Au Sables River as 'pellucid', and he mentions 'small streams of clear water' in depicting the prairie environment. However, we discuss later (page 71) the difficulties in trying to interpret 19 th century descriptions of clear water, which in the context of secchi depths was subjectively different from what …