Here are some frequently asked questions and answers about the Napa River/Napa Creek Flood Protection Project.
Are our tax dollars going for flood protection or beautification?
Fortunately, this Project provides both. The primary purpose of the Project is to protect the community from flooding, but there are also substantial quality of life benefits to come, like Oxbow Commons Park, the six-mile river trail and improved access to the River. Project funds are spent as outlined by the Community Coalition that guided the Project in the late 1990s and by the legal requirements of Measure A that was passed by two-thirds of local voters in 1998.
Are there places that will not have protection after the project is completed?
There are number of specific sites within the Napa project area that will not be afforded protection. For example, areas south of Imola Avenue; most of the east side of the River north of Lincoln Avenue; Compadres Restaurant and Napa Small Animal Hospital just south of Lincoln on the west bank; and the Napa Sea Scout building and Napa Yacht Club building. In order to provide protection for these sites, in some cases it would have been necessary to remove the structures in question, and in other cases the impacts on environmentally sensitive areas was deemed unacceptable in the design phase.
How does the Flood Project protect the community from flooding?
Flood control projects usually seek to impound water through the use of dams; increase the capacity of river channels by dredging, widening, or both; and contain high water with levees and floodwalls. The "Living River" design of the Napa Project is a new approach to Flood Control. Rather than using earlier methods that often diminished the character of natural waterways, the Napa River design maintains the natural channel depth and slope. By employing riverbank terracing techniques, flood flows are given more room to spread horizontally into defined areas. A large area of pastureland at the downstream end of the project was purchased and returned to a wetland environment. This space is capable of holding substantial amounts of excess water. Replacing a number of old bridges that have been determined to block flows is another key ingredient of the plan. And the dry bypass channel for the oxbow area allows a shortcut for fast-moving water that historically has resisted the sharp turns required by the natural geography. The bypass will come into use only when waters rise to flood stage, keeping the oxbow of the River connected to the main channel, and preserving the habitat there. Low flood walls and levees are also required to achieve protection from the "100-year flood".
How is the Flood Project funded?
The money comes from a variety of sources. The local share is generated by the Measure A half-cent sales tax that was passed by Napa County voters in March 1998. The Federal share comes by way of allocations to the US Army Corps of Engineers. These allocations are made annually in the Federal budget process. Additional revenue for the Project has taken the form of grants from FEMA and the Coastal Conservancy, and from the California Flood Control Subventions fund.
I hear people say we’ve had three “100-year floods” in the last 20 years. Is that true?
No, there has not been a 100-year flood recorded since people began keeping these statistics (although the 1986 flood was larger than FEMA’s 1979 estimate of a “100-year flood. Later study of flood records from 1940 to 1988 led FEMA to estimate that the 1986 flood was a “50-year flood.”) That means no one living today has seen a real 100-year flood on the Napa River.
Why is construction of the Project behind schedule?
Money drives construction forward, and there are many reasons why the Project has not received as much money from the federal government as needed to maintain the intended pace of work. The original plan was to have the work done as early as 2005 or 2006. While the local share of funding that comes from the half-cent sales tax has outperformed revenue projections, the Project has not received all the needed funding from the state and federal governments. When the money is delayed, the work is delayed. One of the primary reasons for lower than expected levels of funding is the terrorist attacks of 9/11/01 and the resulting increases in domestic security and military spending. In addition, the Napa Project competes each year with other Corps of Engineers projects, many of which are much larger in scope.
I live far from the Napa River and Napa Creek. Will the Project protect me from flooding in my neighborhood?
No. The Napa River-Napa Creek Flood Protection Project is designed to alleviate flooding up to the level of the “100-year event” in specific areas along the River from Trancas Street to Imola Avenue. Parts of the Project have been constructed downstream of Imola Avenue but “100-year event” protection is not provided in those locations, such as Napa Valley College and Kennedy Park. The Project will also alleviate flooding on Napa Creek east of Jefferson. Flooding problems on other tributaries, such as Dry Creek, Milliken Creek, Tulocay Creek and others will not be affected by the Project. Flooding caused by overwhelmed storm drains will not be solved by the Project. These creek flood zones and interior drainage problem areas are localized and require separate solutions.
Napa Creek floods more often than the River. Why not fix that problem now instead of waiting until later?
All flood protection projects are constructed starting at the downstream end and working upstream. If you change water flows upstream first, flooding will be made worse for people downstream. However, after the 12-31-05 flood, the Corps of Engineers has said they believe the improvements on the Napa River that have been built downstream of Third Street make it feasible for improvements on Napa Creek to proceed at any time. Due to the federal Stimulus funding in 2009, the work on Napa Creek is expected to being in 2010.
Some people say you cannot control flooding on the Napa River because of the tides. Is this true?
Tides do not have any impact on the water level in the City of Napa when the river is flooding. A chart of river levels when there is no flood shows the river rising and falling with the tidal cycle. Charts during a flood show no rise and fall, regardless of the height of the tide. During a flood it’s rainfall and runoff that determines the river level, not the tide. The force of floodwaters is greater than the force of the tide. It is true that high tides can cause flooding in certain areas closer to the Bay. That type of flooding sometimes occurs when there is no rainfall and has no connection to the creek and river flooding we see in most of Napa County
What is a “100-year flood”? Why do we care?
The term is used to describe an event that has a 1-in-100 chance of happening in any given year. When you do the math, there is a 65% chance that there will be a “100-year flood” in 100 years. Likewise, a “50-year flood” has a 2% chance of happening in any given year, and there’s a 4% chance of a “25-year flood” every year. Keep in mind that calculations are based on less than a hundred years of flood records. The reason you often hear the “100-year flood” mentioned is that it’s a yardstick to measure inundation by flooding. Our Project is being constructed to protect the community from this 100-year event, which would be a larger flood than the 2005 event, larger than 1995, even larger than 1986.
What kind of public access to the River will be available after the project is built?
Extensive trails are planned for both sides of the River. On the east and west banks, trails will run north from Kennedy Park into the Downtown area. This east bank trail will be built atop the earthen berm that marks the eastern boundary of the flood plain terrace. On the west side of the River, the path will run along the floodwall boundary, becoming a more urban promenade as it reaches into Napa's Downtown. The western trail will continue above the oxbow all the way north to Trancas. The Lincoln Avenue to Trancas portion of this trail has been completed and is currently in use. Portions of the east trail south of Imola Avenue were completed in 2004. As sections of riverbank improvements are completed, trails will be built, with the pieces eventually linking up to form the complete trail system. In addition to trails, improved access for fishing, boating and other River activities is included in the planning processes of the Flood District and the City of Napa.