Natural Hazards Mitigation

One of the duties of the Planning division includes creating mitigation plans for natural hazards. Information on the natural hazards citizens on Cottage Grove should know about are explained below. Information on Emergency Preparedness can also be found under Emergency Management.  Above are the City's Emergency Preparedness Videos. Information about each of the following Natural Hazards is included below:

The complete updated Natural Hazards Mitigation Plan is available here. 

Natural Hazards Overview Map

Floods

Flood Damage Protection
Cottage Grove's Flood Danger
The City of Cottage Grove is located south of the confluence of the Row River and the Coast Fork of the Willamette River. These two rivers as well as Silk, Mosby, and Bennett Creeks contribute to the flooding hazard in Cottage Grove. The city itself is located wholly within the Coast Fork Willamette Watershed Basin.

Due to heavy amounts of rain, and close proximity to two major rivers and Silk Creek, flooding has occurred in the past in our city. Before Dorena Dam was built, Cottage Grove experienced frequent flooding. The streets of downtown flooded with several feet of water periodically, as shown in this 1927 photo. Although the construction of the Cottage Grove and Dorena Dams between 1942-1945 greatly reduced the threat of flooding in our city, the risk still exists, especially for properties within the 100-year floodplain of the Coast Fork of the Willamette or the Row River and for those along Silk Creek, which has no flood protection impoundments. Silk Creek last flooded over its banks during the flood of 1997.

As a result of this, it is important for citizens to have information on flood damage prevention.

Common terms and definitions regarding Flood Damage Prevention 

Flood Insurance 
Flood insurance is important for anyone within a 100-year floodplain (or even adjacent to a floodplain, since water doesn’t always follow lines on maps).

If you don’t have flood insurance, or don’t know if you have flood insurance, contact your insurance agent. Homeowner’s insurance policies do not cover damage from floods. However, flood insurance is available as a separate policy.

The National Flood Insurance Program offers flood protection coverage for all properties in the United States. The National Flood Insurance Program is operated by the Federal Emergency Management Agency.

Floodsmart.gov, the official site of the National Flood Insurance Program, has an interactive tool that can show you the real cost of a flood to your home. Check out this site to learn the many ways flood insurance can benefit you.

Don’t wait until the next flood to buy insurance protection. There is a 30-day waiting period before National Flood Insurance Program coverage takes effect. Contact your insurance agent for more information on rates and coverage.

Flood Precautions
If you are ever in a flood be sure to follow the these important emergency precautions:

• Don’t walk through flowing water: The number one cause of flood deaths is drowning. Currents in flowing water can be very deceptive; you can be knocked off your feet by as little as 6 inches of flowing water. If you walk through standing water, make sure to use a pole or stick to ensure that the ground is still there.
• Don’t drive through a flooded area: Road barriers are in place for a reason, do not drive around them. More people drown in their cars than anywhere else. Do not attempt to drive through a flooded area, you could easily find yourself stranded.
• Stay away from power lines and electrical wires: After drowning, electrocution is the second most common killer in a flood. Electrical current travels through water. Stay away from down power lines and report them to the Power Company or to the City.
• Have your electricity turned off by the Power Company: Some appliances, such as television sets, keep electrical charges even after they have been unplugged. Do not use appliances or motors that have gotten wet unless they have been taken apart, cleaned, and thoroughly dried.
• Look out for animals: Small animals that have been chased out of their homes by the flood waters may seek shelter in your home. Use a pole or a stick to turn things over and scare away small animals.
• Look before you step: After a flood, the ground and floors can be covered with debris including broken bottles and nails. Floors and stairs that have been covered can be muddy and slippery. Make sure you use caution when walking around after a flood.
• Be alert for gas leaks: Use a flashlight to inspect for damage. Don’t smoke or use candles, lanterns, or open flames unless you know the gas has been turned off and the area has been ventilated.

For more information, please contact the Public Works& Development Department, or check at the City of Cottage Grove Library, where there is extensive information on file related to flood hazards, flood safety, and safe construction techniques.

Floodway & Floodpain Mapping (Summary Natural Hazards Overview Map)
In 1999, the Federal Emergency Management Agency (FEMA) updated its Flood Insurance Rate Maps (FIRM) for Cottage Grove to include the new areas impacted by Silk Creek in 1999. These maps, which show the 100-year and 500-year floodplain and floodways of all three rivers, are available for review at the Public Works & Development Department.  The Flood Hazards Overview Map.

If you have questions about floodplain mapping, please contact the Community Development Department at (541) 942-3340 or come by our office. We will be happy to provide any information we have, including photocopies of FIRM maps. The Community Development Department also maintains records of prior elevation certificates and letters of map amendment, which are available for review.

Wildfires

Wildfire hazards within the City of Cottage Grove occur mostly in the outlying areas of the City: in the north section of the City, in North Regional Park and Mt. David; to the west along the UGB edge including the Grove of Pines development as well as areas behind Bohemia Elementary School and Cottage Grove High School; and to the south on properties along the Willamette River Greenway. Fortunately these are sparsely populated areas. To the east along Knox Butte there is also substantial wildland-urban interface potential. Much of this area is comprised of commercial timber lands under Lane County’s jurisdiction that are zoned F-1 or F-2.

Landslides

Landslide hazards within the City of Cottage Grove are concentrated in the Mt. David area, especially portions of the north, south, and east sides of Mt. David along Holly Avenue and Kalapuya Way. Construction has already occurred on the lower potions of Holly Avenue and portions of Kalapuya Way. Other debris-flow hazards located within the City of Cottage Grove are above and east of the 22nd Street neighborhood. 

Winter Storms

Severe winter storm hazards are located where trees and vegetation align with utility and power lines as well as near roads and houses. Winter storm hazards are located throughout the city. The majority of winter storms result in power outages, blocked streets, and property damage from fallen trees. 

Drought 

Drought has long been considered a slow moving type of event, and though it may not lead to visible, rapid changes, or catastrophic destruction in the short term, the long term effects can be significant.

Earthquakes

Small earthquakes occur throughout the region on a semi-frequent basis. The latest earthquakes in Oregon over 4.0 in magnitude were in Newport on August 18, 2004, and Walterville, Oregon on July 4, 2015 measuring 4.2 in magnitude.

In general the Pacific Northwest and Cottage Grove, is subject to earthquakes of three differing types:

Crustal Earthquakes which tend to be relatively shallow in depth, short in duration, and relatively low on the modified Richter scale - in the range of 1 to 4 in magnitude. These earthquakes represent stresses built up by the presence of the Cascadia Tectonic Subduction Zone, but are not directly linked or connected to it. Shaking tends to be localized, and damages relatively low.
Cascadia Deep Subduction Zone earthquakes are directly caused by Cascadia but occur deep in the earth where the Juan De Fuca plate is singing into the Earth’s mantle. These can cause moderate earthquakes but again tend to cause less damage as they are shorter in duration and lower in magnitude.
​Cascadia Subduction Zone Shallow earthquakes are major events capable of temblors in the range of 8.6 to 9.2 on the modified Richter scale.