Matilija Dam Removal

You must be logged in with an account to view the detailed Location Information. It's free!

N/S ? ??.??? W/E ??? ??.???  [] In California, United States

Print: [5 Logs] [10 Logs] |

Download: [Read About Waypoint Downloads]

| | |

Please note: To use the services of geocaching.com, you must agree to the terms and conditions in our disclaimer.

To get to this location, take Hwy 33 north from Ojai. Turn left on N Matilija Rd. Driving up this windy road you will see a dam with a stair-stepped lowered middle behind you as you drive down the other side of the hill. Parking is available just across the street from the coordinates. Damage to the road has turned a portion into a single lane. An Adventure Pass may be required for parking, but you shouldn't be gone that long.

This earthcach quickly looks at a couple of the effects of dam construction. It also touches on issues that will soon be affecting many older dams across the world.

The Matilia Dam was completed in 1948 by the County of Ventura to provide water supply and flood control for the area. At its completion, the reservoir behind the dam had a capacity of 7,018 acre feet (an acre of land filled to a depth of 1 foot). It was originally estimated that it would take 39 years before the dam would be filled with sediment.

Prior to the dam construction, there was a thriving population of steelhead living in the creek. The dam blocked steelhead migration to approximately 20 miles of habitat in the Matilija Creek upstream of the dam. A year after the dam's completion, a large number of fish were killed behind the dam due to stagnant hot water.

Additionally, The Matilija Dam traps sediment and prevents it from being transported to the Ventura beaches. Along the Ventura Coastline, beach sand is constantly moving southward. Without a constant re-supply of sand from the rivers, the beaches are gradually eroded. See related sand movement on Ventura Beaches Earthcache .

As it turns out the materials used in the construction of the dam makes it potentially unsound. The aggregate (large filler rock in concrete) is alkali-reactive. This means that the cement used in the dam chemically reacts with the aggregate and forms a gel. That gel then absorbs water and expands causing cracking and failure. This problem was brought up by the architect during construction.

In 1964, a safety study condemned the dam and suggest removal. However, the County chose to notch (remove the top part of the dam) and removed the top 30 feet of the dam. This reduced the reservoir capacity by 65%.

In 1969, 21 years after its completion, a 100-year flood event occurred. That single event deposited approximately 27% of the sediment that fills the reservoir (calculated in 2001). As a result, the dam was no longer able to effectively control future floods.

In 1978, the dam was notched again. As a result of the notching and filling up by sediment, the dam currently has a capacity of less than 500 acre feet.

As a result of the reduced capacity and concerns regarding the structural integrity of the dam, the County began plans to remove the dam in 1998. The US Army Corp of Engineers became involved as much of the funding will come from the federal government. This began with a series of studies to evaluate the potential costs of various plans to remove the dam. At the time, it was the largest dam ever proposed for removal. In 2000, Secretary of the Interior Bruce Babbitt symbolically removed a portion of the dam as the start of a demonstration project to determine the most effective way to remove the Metilija Dam. Through this project and other studies, the final feasibility report was issued in September 2004. While funding has yet to be obtained, News reports suggest that work could begin in 2006 and take two years.

I walked down the road to the dam and saw people fishing in the lake. I took the "No Trespassing" signs as meaning we couldn't walk down to the lake and swim in it or climb on the dam.

Logging requirements:
Send me a note with :

1. The text "GCPRZ0 Matilija Dam Removal" on the first line
2. The number of people in your group.
3. What evidence can you can see indicating that the dam is no longer useful for flood control
4. Alternately, post your thoughts on the various options you can think of for safely demolishing the dam and restoring the creek to a natural flow (any logs with off the wall or sarcastic suggestions will be deleted).

The following sources were used to generate the information in this cache:

• http://www.matilijadam.org (It has historic pictures and pictures of recent flood events. It also has a more detailed history)
• http://www.doi.gov/news/archives/001012.html
• http://ca.water.usgs.gov/cgi-bin/influx/projectsapp.pl?preview=57
• http://pages.sbcglobal.net/pjenkin/matilija/spilling.htm
• September 23, 2004. Feasibility Report for Matilija Dam Ecosystem Restoration Feasibility Study, Ventura County, Ventura, California, US Army Corps of Engineers. http://www.matilijadam.org/final/notice.pdf
• March 27, 2004, Matilija Dam Removal Project Backed Up, Los Angeles Times http://www.nrmbc.org/News/0005-MatilijaDam/NewsPage.htm
• Sherman, Douglas J., Karmon M. Barron, and Jean T. Ellis, Retention of Beach Sands by Dams and Debris Basisns in Southern California, Journal of Coastal Research, Spcial Issue 36, 2002

Find more Earthcaches

Additional Hints ( Decrypt ) 

Decryption Key
A|B|C|D|E|F|G|H|I|J|K|L|M
-------------------------
N|O|P|Q|R|S|T|U|V|W|X|Y|Z
(letter above equals below,
and vice versa)

jung naq jurer vf fghss tebjvat va gur jngre (Decrypted Hints)

Find...

• ...other caches hidden or found by this user
• ...hotels near Ojai

Logged Visits ( 49 total. Visit the Gallery (22 images) )

46

2

1

Cache Logs

September 8 by PathfinderMark (875 found) Matilija Dam Removal was transferred from TerryDad2 to user PathfinderMark [view this log]

September 5 by Thunder-4 (5044 found) Made this find along with 234 other finds with FlagMan over the Labor Day Weekend! We found caches along highway 33, in Ventura, Thousand Oaks and Burbank. It was an epic weekend. Thanks for hiding this cache! Email sent. [view this log]

September 5 by FlagMan (8731 found) I came up with Thunder-4 on the usual pilgrimage for numbers that San Diego cachers must take every so often. Thanks for the Northern SoCal hospitality!! We logged in alternatively as FM + T4 or T4 + FM, depending upon which one of us had the pen in hand at the time. We got 174 on the day, coming up just short of our friends DLT! TNLNSL Thanks for the fun and Happy Hunting! [view this log]

August 13 by lulu499 (5042 found) This day will definitely go down as one of my most memorable caching days yet. Up from San Diego with Duncan! and Triple Crown with the goal of finding 100 caches in one day. We exceeded our goal by 76, thanks to D!'s outstanding planning skills!!! We signed the log as DLT! to save time. Thanks for the cool earth cache. Email sent by Triple Crown, but I'll be happy to send a seperate email, if necessary. [view this log]

August 13 by Triple Crown (4396 found) D L T ! (Duncan!, lulu499 and Triple Crown) came up to the Ventura area for some power caching. We bagged 176 smileys with only 10 DNFs today as we toured Ventura, Ojai and Santa Paula. The caching was epic and the company was awesome! SL TFTC!!! e-mail sent. Thanks for the lesson! [view this log]

Current time: 11/22/2009 11:08:18 AM
Last Updated: 9/9/2009 5:12:02 AM
Rendered: From Database
Coordinates are in the WGS84 datum