Drainage Improvement Program

Citizens with concerns about drainage issues that have caused or are threatening damage to private properties may utilize the Drainage Improvement Program to request City-funded improvements. New drainage system projects, improvements to existing drainage systems, improvement of outlets, and projects to impound, reroute, or divert drainage system waters may be requested through this program.

Stormwater Management Introduction

Underneath our bustling streets and sidewalks lies a network of pipes that form the stormwater drainage system. When rain falls, runoff from hard surfaces like roads and rooftops is swiftly directed into storm drains, then channeled through these pipes before being discharged into nearby streams. Unlike water in the sanitary sewer system, stormwater remains untreated, carrying with it pollutants it picks up along its path, including sediment, litter, fuel residues, and other chemicals. 

Impervious surfaces like roads, parking lots, and rooftops from urban development significantly alter natural runoff and flow patterns. These surfaces prevent rainfall from soaking into the ground, leading to faster and greater amounts of water entering storm drains, rivers, and other bodies of water. This results in more frequent and severe flooding.

Traditionally, our built environment has relied on gray infrastructure—storm drains, pipes, and gutters—to manage flooding by directing rain water away as swiftly as possible. However, the sheer volume and velocity of this concentrated stormwater strains local waterways, delivering pollution and increasing erosion in our streams.

Understanding Storm Frequency

Oftentimes storm events are classified based by their size, intensity and frequency. For example, a larger, more intense storm is the 100-year storm. Admittedly, use of such terms as the “100-year storm” can confuse or unintentionally mislead those unfamiliar with storm events. Because of the potential confusion, the U.S. Geological Survey, along with other agencies, is encouraging the use of probability terminology instead of the recurrence interval terminology. For example, one would discuss the “1-percent storm” as opposed to the “100-year flood.”

These designations are based on statistical probabilities rather than specific time intervals, meaning that a 100-year storm could occur multiple times within a century or even within a year. One way to think about these probabilities is to think about flipping a coin 10 times. Even though there is a 50% chance of getting heads, it is possible to get heads more than 5 times. 

 

Recurrence	Annual Exceedance Probability
Interval	(% Chance occurring within a year)
1 year	100%
2 year	50%
10 year	10%
25 year	4%
50 year	2%
100 year	1%
200 year	0.5%
500 year	0.2%

The definition of a "100-year flood" can change over time. Local land use changes, an increase in impervious surfaces, soil saturation, and long-term climate trends can all impact what we consider a "100-year flood" today.

Understanding Drainage Within the City

Your property is not an island. It is connected to the surrounding landscape. Your property may have utility easements, drainage easements, or stormwater management infrastructure.

Who maintains the drainage system?

City drainage systems

• The City maintains the public storm drainage system contained within dedicated storm drainage easements where the City of Harrisonburg is identified as the responsible party. The City also maintains the storm sewer systems in public street rights-of-way. 

Private drainage systems

• Storm systems on land owned by other individuals and entities are part of the private drainage system. There are numerous private systems that are the responsibility of private property owners. These systems are privately owned and maintained even when they connect to portions of the public drainage systems. In fact, most drainage systems in the City are privately owned and maintained.
• Drainage Easements on Private Property: An easement is a right granted from a property owner to another for a specific use of a portion of the owner's land. Utility operators (gas, electric, sewer, etc.) often have easements for the purpose of installing and maintaining their utility lines and structures. Many drainage easements are established by property developers at the time of development to denote stormwater facilities and drainage flows and assigning maintenance responsibility to a HOA or the future landowner. The City is not involved in creating or approving these easements. 
• Private Drainage and Erosion Issues: Private drainage and erosion issues, as well as ground water issues, are the responsibility of the property owner. Drainage directed from gutters, downspouts or other private systems to neighboring properties is a civil matter between the property owners. 

How to Apply For the Drainage Improvement Program

English:

Drainage Improvement Program Manual [1MB]

Application [766KB]

Program Process [766KB]

Spanish:

Política de Mejoras de Drenaje de la Ciudad de Harrisonburg [402KB]

Solicitud del Programa de Mejora de Drenajes [203KB]

Programa de Mejora de Drenajes [142KB]

Recommended Stormwater Drainage Projects List

Please contact the Public Works Department for questions or help with the application process. 

Phone: 540-434-5928

Email: stormwater@HarrisonburgVA.gov

Address: 320 East Mosby Road, Harrisonburg, VA 22801