Still supported by a nearby stationary front, a second round of thunderstorms dropped another 3-5 inches of rain across northwest Illinois during the overnight hours of July 23rd into the early morning of July 24th.  This additional heavy rain exacerbated the ongoing flooding from the night before and caused even more extensive and severe damage.  Yellow Creek and the Pecatonica River (Stephenson County), the Apple and Galena Rivers (Jo Daviess County), and the Plum River were most notably affected.

Flash Flood in JO DAVIESS, ILLINOIS
From 24-JUL-10 03:15:00 to 24-JUL-10 07:00:00 (CST-6)
Location: EAST DUBUQUE
Flood cause: Heavy Rain
Property damage: 500.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Heavy rains during the late night of July 23 and early morning of July 24 resulted in flash flooding of much of Jo Daviess County during the morning of July 24.  Major flooding was observed along the Apple River near Elizabeth, where the river level was just below the bridge deck of Highway 20.  Water rescues of stranded motorists were performed near Galena, Stockton, and Scales Mound between 4 am CDT and 630 am CDT.  A bridge was washed out near Little Rush Creek and Bethel Road about 3 miles east southeast of Elizabeth, IL.  A grocery store in Stockton was flooded with 3 inches of water.
Galena closed their flood gates around 5 am CDT on Saturday the 24th, and the Galena River crested about 3 feet high in front of the gates.

Flash Flood in CARROLL, ILLINOIS
From 24-JUL-10 05:00:00 to 25-JUL-10 07:00:00 (CST-6)
Location: LANARK
Flood cause: Heavy Rain
Property damage: 10.00M
Crop damage: 0.00K
Reported by: Newspaper

After about a foot of rain in 2 days, creek and small river basins rose rapidly Saturday morning.   Numerous rural roads throughout the county suffered from washouts and excessive erosion.  Near Argo Fay, Johnson Creek overflowed its banks and closed Big Cut Road.
In Mount Carroll, flooding of the Waukarusa River forced evacuations of about 80 homes, mainly on or near Mill Street.  The local fire chief estimated that 80% of Mount Carroll residences had water in their basements.
The Plum River overflowed its banks between Lake Carroll and Savanna, causing extensive and severe damage.  Just west of Lake Carroll, a farm house on Polsgrove Road flooded.  The resident of the home described the event, saying that around 5 am there was no sign of flooding nearby, and by 7 am water was in the house.
As the flood waters approached Savanna, the Plum River either overflowed or breached (it is unclear which) a high bank along Scenic Bluff Road, flowing then through the railroad yard to the Mississippi River.  Local residents describe water rising about 4 feet in literally a few minutes.  In Savanna, an estimated 625 people were evacuated, mainly from the eastern and southern portions of town. Due to the rapidly rising water, first responders in Savanna rescued more than 60 people from their homes. At least 12 homes suffered water up to the first floor and a Swiss Colony factory had several feet of water throughout its facility.  Emergency management estimated 10 homes completely destroyed and 75 seriously damaged in Savanna alone.  The raging flood waters washed away more than 30 yards of embankment supporting an overpass on the Highway 84 viaduct, washing away two rows of pylons that were supporting the bridge and closing the primary access route south of Savanna indefinitely.  Numerous rail cars in the train yard were overturned, some of them washed up against bridges.  Both DM&E and Burlington Northern suffered damage to their rail lines.

Flash Flood in STEPHENSON, ILLINOIS
From 24-JUL-10 03:00:00 to 24-JUL-10 07:00:00 (CST-6)
Location: WINNESHIEK
Flood cause: Heavy Rain
Property damage: 500.00K
Crop damage: 0.00K
Reported by: Newspaper

Heavy rains of about 3 inches in under 3 hours (for a total of about 11 inches in less than 32 hours) resulted in extensive flash flooding during the morning of July 24.  The greatest impact was flash flooding of Yellow Creek from Pearl City to Freeport, with additional impacts from flash flooding of the Pecatonica River in and near Freeport.
Local emergency management officials described the flood damage as the worst damage I've seen in 19 years, and many lifelong residents affected by Yellow Creek described it as worse than anything they had ever experienced in their lifetimes.
Forty-three roads in Stephenson County were under water and closed to traffic, including Business Highway 20, Highway 20, and Route 75.  Streets in downtown Freeport had as much as 5 to 6 feet of water.  Some people who were trapped in flooded vehicles were rescued by boat.   In the weeks following the flash flood, more than 20 sink holes developed in Freeport roads.  The Stephenson County engineer documented about $1 million in damage to county and township roads.
In Pearl City, about 80 homes were damaged in the flooding of Yellow Creek, and an additional 60 homes in unincorporated portions of the county we also damaged.  One Pearl City resident awoke around 3 am CDT to the sound of trickling water to discover his possessions floating in 3 feet of water.
More than 700 homes and countless businesses in Freeport were damaged. Numerous stores in the Southgate Market area were flooded and remained closed for at least 2 weeks, some for as long as 6 weeks.  Also affected was the Winneshiek Playhouse, the oldest amateur theater in the United States, which suffered 3 feet of water in its basement.  Freeport Fire Station 3 was nearly completely under water and was evacuated due to the flooding.   Due to repeated rounds of heavy rain (with nearly a foot of rain measured in less than 48 hours), the Freeport wastewater treatment plant sustained about $1.4 million in damages.