Stormwater – precipitation that does not soak into the ground – can have a large impact in a short amount of time. Rain falling on a grassy area is slowed by the leaves and stems; these areas hold about 90% of the water. Rain falling on a paved driveway picks up momentum as it flows toward the nearest low spot; these areas catch very little water. Each new stretch of pavement or hard surface in a town sends more runoff toward drainage systems.

How much runoff are we talking about? That depends on where the rain is falling. In Grand Island, we can find:

– average annual precipitation: 26 inches

– recent size of the city: 30 square miles

So if 1 square mile receives 26 inches in 1 year, and Grand Island is about 30 square miles, then Grand Island receives about 521.4 million gallons of precipitation each year.

But Grand Island isn’t all hard surfaces or all green space, we have a mix. Experts in this area agree that small urbanized areas in rural communities lose about 30% of precipitation as runoff. Another quick calculation (30% of 521.4 million) gives us about 156.4 million gallons each year that don’t soak into the ground. 156.4 million gallons of water rushing off to… somewhere. 

How much water?

Let’s zoom in. If you were to catch each drop of rain that falls on a 1,200 square foot roof, after 1 inch of rain you would have 748 gallons of water. If you tried to catch each drop from a 1-acre parking lot, after 1 inch of rain you would have 27,000 gallons of water.

The problem

Americans have been working on cleaning up our waterways for over 50 years. Industries have been held accountable for their pollution. Farmers are being held accountable for their runoff.

Cities are now a leading source of pollution in lakes and rivers.


There are lots of hard surfaces downtown. On a sunny day, those surfaces can give off enough heat to raise the temperature 10*F in the downtown area. Runoff from this ‘heat island’ is warmer than runoff from residential areas – so much warmer that it raises the temperature of a stream more than 7*F.

Lawn Chemicals

Neighbors work hard to have lush, green lawns. We use toxic chemicals like weed killer and fertilizer without reading the package and we use TOO MUCH. Any extra chemical the plants can’t use is washed away by the rain … into our lakes and streams.

Residents of Central Nebraska rely on clean water.

Tourism in Central Nebraska relies on clean water. 

Screenshot 2024 05 07 195221