Devil’s Gate Dam

The proposed Devil’s Gate Dam sediment removal project will impact Altadena greatly, and for years to come. At December’s annual meeting, members voted to present Altadena Heritage’s position on this project by responding to the Draft Environmental Impact Report prepared by the Water Resources Division of L.A. County’s Department of Public Works. The response below covers community concerns to be aware of, and asks important questions about the project that AH wants answered before any action is taken. Please read it, and if you, too, are concerned about the impact of the proposed project, you have until Jan. 21 to send your own comments to the the LACPW at this address:

If you’d prefer to provide input via e-mail, the address is: reservoircleanouts@dpw.lacounty.gov

Your Feedback — as a citizen of the most-affected community — will go a long way toward helping us achieve our goal of finding a less intrusive and more sustainable solution for the problems the proposed sediment removal project purports to address. More information is available at savehahamongna.org, and AH will continue to keep members updated on this important issue.

Gail Farber, Director
Los Angeles County Department of Public Works
Attn: Water Resources Division — Reservoir Cleanouts
P.O. Box 1460
Alhambra, CA 91802-9974

 

Devil’s Gate Reservoir Sediment Removal & Management ProjectAltadena Heritage is a volunteer-based organization active since1980 and registered as a 501(c)3 corporation in 1987. We are dedicated to protecting, preserving, and raising awareness of the architectural, environmental, and cultural heritage of our community. We have 450 members interested in preservation and advocating for a more beautiful Altadena.  At our annual members meeting on December 15, 2013, members voted to respond to the Draft Environmental Impact Report for Devil’s Gate Dam Sediment Removal Project. A major portion of Altadena’s western boundary runs along Hahamongna Watershed Park and the Devils Gate Dam area, and any of five alternatives proposed in this DEIR would impact our community immensely. We recognize the need to remove sediment, maintain the dam, and protect downstream public safety, but we have serious questions regarding the project’s magnitude and timeline, and are concerned that best management practices for integrated watershed management are not incorporated in any of the proposed alternatives.We look forward to reviewing your responses to our comments and questions as follows:

  1. Why has the project grown from its original proposed goal of 1.67 million cubic yards of sediment removal to 2.4 – 4 million cubic yards?  What hydrological studies or other science justify this major increase in scope? Please refer us to specific reports.
  2. The sediment basin is Pasadena’s, Altadena’s and La Cañada’s Hahamongna Watershed Park, an important regional resource used for recreation by thousands of local residents. Activities include hiking, horseback riding, bicycling, and bird-watching. Have alternatives that allow debris removal while retaining multiple benefits for multiple users been considered? If yes, why have these alternatives not been presented? If not, why not?
  3. Proposed construction plans block the two main east-west trails.  The top of the dam is the trail connector to north-south trails, and blocking this will prevent passage to Pasadena and trails to the south. East-west blockages will prevent passage west to La Canada Flintridge trails. Is there a way to retain trail connections during debris removal? Is there a plan for trails following debris removal?
  4. The debris basin provides important wildlife habitat for numerous species of vertebrate and invertebrate animals, and serves as an important wildlife corridor bridging the front range of the San Gabriels with areas to the south. What protections of wildlife habitat and migration routes are being proposed for the project?
  5. Is trucking the only solution for debris removal? The plan for 450 truck trips per day, 6 days per week, up to 12 hours per day, 9-10 months a year for 4-7 years will negatively affect quality of life for Altadena’s 43,000 residents — and is both energy intensive and expensive. Altadena will bear major health impacts of increased traffic and pollution for years under all trucking alternatives proposed in this DEIR. Has the cost of these health impacts been assessed in the DEIR?
  6. The Eaton Canyon/Devil’s Gate Water Diversion Project’s cumulative impacts, when combined with the Sediment Removal Project, have not been addressed sufficiently, but merely alluded to in this DEIR.  We refer to the planned 4,500 acre-foot-per-year (as stated in the Proposition 1E application and other documents) water diversion via a 4.8 mile long 30 to 36-inch pressurized pipeline which is slated to run for virtually its entire length through Altadena from Devil’s Gate dam to Eaton Canyon spreading grounds. Estimated cost for the diversion is $10 to $15 million. This project will require a large storage pond and a pumping station within the Devil’s Gate Dam area, yet the Diversion Project and Sediment Removal project are not considered together. Why not?The Diversion Project will result in torn up streets near several schools and in quiet neighborhoods, trucking, traffic delays, and pollution for the one and a half to two year estimated construction period. This will impact Altadena greatly. Why is it necessary to transfer this water 5 miles across Altadena instead of allowing it to settle within the Devil’s Gate area? The percolation rate in Devil’s Gate is similar to that in Eaton Wash, and the water would replenish the Raymond Basin Aquifer if allowed to percolate closer to where it naturally flows. This would benefit Altadenans and Pasadenans without the cost and disruption of a pump and pipeline project. What is the rationale for installing the pipeline rather than allowing natural percolation at Devil’s Gate? The estimated cost of $10 to $15 million seems low for this project. Is this estimate realistic?
  7. On the other hand, the size and price tag of sediment removal, $65-100 million, is high. Have less expensive approaches that accomplish identified goals been considered?
  8. The DEIR consistently treats sediment as trash instead of a resource. Clearly, much of it has value, especially if allowed to work its way down to help build up eroding beaches at the other end of the system. Sediment could be exported by sluicing, or by conveyor belt to existing channels of the Arroyo Seco and on to the LA River. Some sand, rock, and gravel could be separated in Hahamongna for local use. Exporting even a portion of the sediment by means other than trucking via freeways to Irwindale would seem to be more sustainable and could result in substantial savings. Have these alternatives been fully explored and potential cost savings assessed?
  9. We seriously question the advisability of removing sediment in a single large-scale engineering operation. Debris accumulation is continuous over time, so a debris basin can never be permanently emptied. A maintenance approach limiting work to a few months a year in defined areas of the basin would allow for continuous on-going maintenance, and reduce the size of yearly export with associated dust, noise, hydrocarbon pollution, and freeway congestion. Construction areas could be cordoned off to allow for recreation and wildlife habitat in other areas. An important plus would be guaranteed jobs for workers and local trucking firms into the foreseeable future, and the opportunity to sort valuable building materials on site for sale to local contractors and homeowners. Has such an ongoing maintenance program of debris removal been assessed? If not, why not?

Altadena Heritage understands and supports the need for flood control and dam maintenance but questions the size and detrimental impacts of alternatives described in the DEIR. This DEIR does not appear to make use of current well-accepted multiple beneficial uses and best practices, but instead harkens back to single-goal civil engineering practices of the past. Please consider the quality of life and health of all in this area, and develop more viable and creative alternatives. In fact, such alternatives may lead to cost savings.

Respectfully yours,

Mark Goldschmidt, Chairman
Altadena Heritage

Pin It on Pinterest

Share This