On Wednesday, July 12, 2017, the Village of Lake Bluff experienced a significant rain storm that has been estimated as a 140-year storm by Lake County. The Village saw about 7 inches of rain in less than 10 hours. This resulted in flooded basements and the closure of many local streets such as Green Bay Road and highways including Route 176 and Route 41. Due to the scale and damage of the storm, the State of Illinois and Lake County declared an emergency. The Federal government may also declare the July 12 storm to be a natural disaster. This exceptional rain storm was followed by two other significant rain events occurring on July 20 and August 3. More flooding occurred in the Village due to the saturated ground and high intensity of rainfall, although it was not as damaging as the July 12 storm.

So, July was a very wet month for the Village. How does storm water flow in the Village?

Yes, very wet -- July saw twice as much rain as we normally get on average. Rain first soaks into the ground and then flows from high areas to low areas as the ground saturates. Before humans developed this area, water would flow naturally into ravines and creeks. In the Village, runoff east of Green Bay Road generally drains into Lake Michigan near Sunrise Beach. West of Green Bay Road, storm runoff drains into the East Skokie River.

What does the Village do to protect us from stormwater?

We start worrying about stormwater as we start to develop an area. The construction of homes and businesses create hard (“impervious”) surfaces that soak up less water and send it elsewhere faster. This increases the size of floods in low-lying areas and the velocity of moving water. Through our development regulations, the Village restricts the amount of impervious surface on a lot to reduce this effect. 

We also provide protection for property through stormwater systems – usually at the time of development. Stormwater systems are designed to protect property by piping water away and by moving it on streets and over land. As is the case in many communities, Lake Bluff’s public infrastructure is designed and built to accommodate a moderate storm within the storm sewers (pipes). As the intensity of the storm increases, by design, more water flows on streets and over land until it reaches a waterway or a storm sewer with more capacity. The ultimate design goal of modern infrastructure is to prevent property damage in the 100-year storm.

What do you mean when you say a 100-year storm?

Stormwater experts determine how protected an area or structure is based on how big of a storm can be handled without damage to property. Designers use the probability of a storm occurring each year to identify the level of protection, as well as how severe a storm event was. The term “100 year storm” is an expression for a storm with a 1% chance of occurring each year; the “10 year storm” has a 10% chance each year; the “5 year storm” has a 20% chance each year. It is possible to have multiple “10 year storms” in just a few years – the same way as you can get “tails” three times in a row when you flip a coin.

What areas of Lake Bluff were affected by the July 12th flooding?

There isn’t a neighborhood in our Village that was unaffected by flooding. Again, we’re talking about a natural disaster. We estimate that at least 70 people had water in their basement for one reason or another, such as a sump pump power failure or groundwater seepage through basement walls.

Still, the Village observed significant flooding at:

  • Scranton Avenue Viaduct (under Sheridan Road)
  • Lincoln Avenue, south of Scranton Avenue / Route 176
  • Campbell Court, north of the Tangley Oaks subdivision
  • West Sheridan Place, west of Lincoln Avenue

Doesn't the Route 176 Viaduct (Scranton Underpass) flood all the time?

No – but it can be very disruptive when it does flood. Village records indicate the Viaduct has been closed seven times in the past five years due to large rainfalls.

What about the Route 176 Viaduct (Scranton Underpass)... What is the Village doing?

The Viaduct is under the control of the Illinois Department of Transportation. IDOT is responsible for its maintenance and management. Lake Bluff's Police and Public Works departments only watch it and close it when it is unsafe. The Village has expressed its concerns to the State for years with no solution. However, a recent study showed that it would cost over $18 million dollars to protect the Viaduct from flooding under modern design standards.

What is the Village doing to help limit future flooding?

The Village and its engineers are using the July 12 storm to confirm past studies and identify potential projects to reduce flooding. The Village is always evaluating, monitoring and investing in public infrastructure. This infrastructure includes streets, sidewalks, water pipes, sanitary sewer pipes, and storm sewer pipes. The Village is exploring potential projects, as well as stormwater pipe expansions that will better protect low lying areas. In a few problem areas, fixes would either cost millions of dollars or would trigger flooding elsewhere. There are no easy answers for some of these problems, but we’re going to keep working on solutions.

You must know: no improvements by the Village will completely end the risk of flooding. Again, the cost just to reduce water levels in the Viaduct exceeds $18 million dollars. To put it in perspective, that is as much property tax as the Village collects in half a decade. And, it is likely that stormwater improvements to the Viaduct may not have kept the viaduct from closing during the July 12 storm. It’s a major investment to build stormwater infrastructure that can weather the 100-year storm; it is extremely rare for any community to design their system to handle anything more severe.

What can I do to protect my home from flooding?

LOOK AT THE TERRAIN AROUND YOUR HOME: Small drains in your yard can’t handle large storms. Grades should direct most water away from you and your neighbors’ homes and toward the street.

SCOUT OUT WHERE YOU ARE SENDING WATER: Some homeowners don’t realize that they are causing water problems for their neighbors by directing downspouts and sump pumps toward their property line. Cooperating with your neighbors to grade common lot lines would fix many runoff problems in our Village.

IMPROVE YOUR SUMP PUMP: Ensure your sump pump has backup power, whether it comes from a battery or a generator. Consider upgrading it to make sure it can move water out of your home before it can reach your belongings.

FORTIFY YOUR FOUNDATION: If grading doesn’t solve the problem, you can install French drains, seal foundation cracks, and waterproof basement walls. These techniques may help prevent water from entering your basement.

CONSIDER FLOOD INSURANCE: If you only had a flooding problem on July 12, you may not need to worry about future damage. However, you should consider your options carefully. In the event of a flood, your homeowner’s insurance may not cover the damage so it is advisable to speak with your home insurance provider about coverage options.