Drought conditions were of primary concerned during the 2005 water year. According to a report at the Drought Response Task Force meeting on September 29, 2005, March - September was the 6th driest ever observed in Illinois. Annual runoff was below normal in the northern part of Illinois. Annual runoff at the northern index station--Pecatonica River at Freeport (05435000--was 803 ft3/s or 85 percent of the 30-year (1961-90) average runoff of 947 ft3/s. A comparison of the 2005 daily discharges for three index stations and the mean-daily discharges for the 30-year period (1961-90) is shown in figure 1. Runoff at Freeport was generally near normal or below normal during most of the year, except for the months of January and February, which were above normal. Even though northern Illinois experienced heavy rainfall and flooding during January and February, annual precipitation was nearly 8 inches below normal (from data map-Midwestern Regional Climate Center's Web site), which contributed to the below-normal annual runoff. The U.S. Drought Monitor indicated "extreme" drought conditions for much of northern Illinois from June through the end of the year.
Even though drought conditions were the precedent during the second half of the water year throughout most of the State, annual runoff was above normal in the central and southern parts of the State. Annual precipitation in southern Illinois was generally 2-4 inches above normal (from data map-Midwestern Regional Climate Center's Web site), which helped to reduce the drought conditions during parts of March through September. A major precipitation contribution came from Hurricane Katrina in the Gulf of Mexico, which produced large mounts of rainfall in southern Illinois during the last couple days in August. At the center index station--Sangamon River at Monticello (05572000)--, runoff was 584 ft3/s or 136 percent of the 30-year average of 430 ft3/s. At the southern index station--Skillet Fork at Wayne City (03380500)--, runoff was 543 ft3/s or 134 percent of the 30-year average of 406 ft3/s. The central-index station at Monticello and the southern-index station at Wayne City had events of above-normal flows during parts of October 2004 - February 2005. The remaining months of the year had near to below normal flows.
Table of Contents |
Introduction |
Station Description |
Surface-Water Data |
Ground-Water Data |
Meteorological Data |
Biological Data |