City of Roseville

Floodplain Boundaries - Most of Roseville is “high and dry” as less than 7% of the City is within a floodplain, and most of the floodplain property is open space (no homes). The Engineering Division has the floodplain boundaries mapped. Since 1986, the City’s development standards have not allowed new buildings to be built within the flood hazard areas. However, there are some areas along our creeks in the older areas of the city, primarily along Dry, Linda, and Cirby Creeks, where flooding would result in damage to properties.

Current Requirements - Building or filling within the 100-year floodplain is prohibited except in the Infill (central) area of the City and only if no impact is demonstrated. In all cases, the floor elevation of any structure is required to be at least two feet above the “future” 100-year floodplain's water surface elevation. “Future” means the drainage shed is assumed to be built out to the year 2040.

Flooded Structures - In 1986, 209 structures incurred flooding. In 1995, 358 structures incurred flooding. There was more intense rainfall in 1995 than in 1986. Most homes that flooded were constructed prior to floodplains being mapped. No structures in Roseville built since 1980 have incurred flooding.

Nolte Study - In 1985/86, Nolte updated the 100-year floodplain elevations. We use Nolte for establishing minimum floor elevations. Cost of study = $1 million.

Alert System - After the ‘86 flood, we installed an alert warning system with 18 rain gauges, 19 stream level gauges, and a computer monitoring system. We also monitor Doppler radar and satellite imaging of incoming storms to assist us in advance notification efforts in the event evacuation of flood-prone areas is deemed necessary. Public safety uses Placer Alert to notify the public in an emergency. In summer 2001, real-time stream gauge data became available online at roseville.ca.us/streams. Installation cost of ALERT system = $625,000. Annual cost to maintain = $150,000.

Annual Streambed Maintenance Program - After the ‘86 flood, we entered into a Memorandum of Understanding with the State Department of Fish & Game to allow us to clear creeks of fallen trees and debris which could otherwise float downstream and block culverts and bridges. Annual cost = $100,000.

Placer County Flood Control District - In 1989 we participated in creating the District. The District generated the Dry Creek Watershed Flood Control Plan that includes regional detention basins and other improvements within the Dry Creek basin. The District adopted a developer-paid fee to help fund these improvements. The District established improvement standards for development, and reviews development proposals. Up front cost = $300,000. Annual cost = $90,000.

Cirby-Linda-Dry Creek Flood Control Project & Environmental Impact Report (EIR) - In 1989/93 we developed a Conceptual Design Report and an EIR for the Cirby/Linda/Dry Creek Flood Control Project. The project is designed to provide increased levels of flood protection to 262 structures in Roseville. Cost of report and EIR = $1.5 million.

FEMA'S Community Rating System - By implementing good floodplain management practices, Roseville became the first community in the nation to receive the Federal Emergency Management Agency's (FEMA’s) Community Rating System (CRS) highest rating of Class 1. This rating allows Roseville property owners up to a 45 percent discount on their flood insurance premiums. 

The City of Roseville has been actively involved with FEMA’s CRS Program since 1992. This program rates communities on how effectively they manage their floodplains. The program rates cities in the following four major categories.

• Public Information

• Mapping and Regulatory Standards

• Flood Damage Reduction

• Flood Preparedness

This is the highest rating that a community can obtain.