IN THE SUMMARY TABLES OF THE 30 SITE DESCRIPTIONS, THE FOLLOWING SHOULD BE NOTED: The slight variation of total acreage of RRAs listed in the Summary table and the Land cover table is related to the use of different analysis methods. Acreage in the publication are generated from digital coverages and are not authoritative; they may differ slightly from acreages listed I other sources. For Illinois natural Areas, some sites are represented in the geographic information system only as point locations because maps were not available at the time of this analysis. Therefore, no acreages were listed for these sites, identified with an *. Some of the features included in the Biologically Significant Streams Inventory are lakes, in which case the mileage was calculated a the perimeter of the lake. I the analysis of Heritage occurrences, the stream community type was not used because of the difficulties of using point locations as representations for stream lengths and because significant streams were well represented in other tables (Natural Areas Inventory and Biologically significant Streams). State land in this publication is limited to parks, conservation areas, forests and fish and wildlife areas.
EACH RRA IS REPRESENTED BY A NATURAL RESOURCE MAP AND A LAND COVER MAP. Feature labels are generally to the right of the feature unless this was not possible. The maps were designed to maximize the area on the page, therefore scales vary between maps. A key to the feature names contained on the maps follows.
| Natural Area | |
| Natural Area represented as points | |
| State Park | |
| State Conservation Area | |
| State Fish and Wildlife Area | |
| State Forest | |
| National Forest | |
| National Wildlife Refuge | |
The Shawnee National Forest is represented on the maps by many scattered ownership boundaries, which are unlabeled, and a more general proclamation boundary.