The City of Napa's Drainage Program was established to improve, operate and maintain drainage infrastructure within the City. The primary goal is to establish a reliable drainage conveyance system and improve existing drainage infrastructure. This is accomplished through a large network of drainage and stormwater infrastructure that includes catch basins on street surfaces that capture stormwater and carry it to the City's Municipal Separate Storm Sewer System (MS4). 

The City's MS4 consists of over sixty-five miles of underground concrete pipes that transport rainwater to creeks, channels, and ultimately the Napa River. This system helps to reduce the flooding of private and public property during the many rainfall events that occur throughout every year. 

Storm Drain Asset Management

The City manages a variety of stormwater and drainage assets that include: catch basin, distribution lines, culverts, open channels, detention basins, and outfalls through both physical and digital asset management systems. Currently, the program maintains these assets in a variety of formats that include - Geographic Information System (GIS) data layers, Computer Aided Design (CAD) Files, and physical records and historical drawings. 

In addition to the assets that we currently maintain, City staff is working on developing a software model that can simulate the City of Napa drainage system. This model would give staff the ability to determine various features related to flood control and stormwater drainage; such as watersheds for individual catch basins, time of concentration for city watersheds, flow capacities of new and existing drainage pipes. 

An interactive drainage map is on the horizon to be published online making this information available to the public as well. This interactive map shows the location of drainage pipes, drain inlets, and outfalls. By using the search bar an area of interest can be located by either street address or assessor parcel number (APN).

Reporting Drainage Problems

One of the many responsibilities of the drainage program is to respond to the public regarding drainage complaints. To complete an online drainage maintenance request please visit the City of Napa Service Center. To call in a drainage complaint the City drainage contact may be reached at 707-257-9520.

Within the City of Napa there are both public and private drainage assets. The City does not provide maintenance for privately owned drainage inlets, detention ponds, or other drainage infrastructure. 

The City holds drainage easements that convey stormwater through publicly owned drainage systems and through some private properties. If you are unsure whether a storm drain asset is publicly or privately owned, please check the interactive drainage map above or contact the City for more information.