Hahamongna On-Site Storage Unlikely for Dam Clean-out

A plan to for a clean-out of Devil's Gate Dam appears to be dead, as Pasadena officials have decided not to consider giving permission to store accumulated mud on site in the Hahamongna Watershed Park.

Consideration of storing excess debris at Johnson Field had been planned for consideration at tonight's Pasadena City Council meeting. but was pulled from the agenda.

The influx of traffic would be the result of a plan to clear about 25,000 cubic yards of dirt, sediment, and debris that is part of the nearly 2 million cubic yards that has accumulated in the Altadena-adjacent dam from winter storms. 

The lack of vegetation in the San Gabriel Mountains from the 2009 Station Fire has resulted in an unusual volume of dirt build-up, and county officials now need to began an urgent clean-up process of the 25,ooo cubic yards closest to the dam before the upcoming rainy season.

How to get all that dirt out of the dam has become a point of contention as it would require several months of hauling dirt. If the county does not get Pasadena's permission to store it on site, it will mean high volumes of truck traffic for several months through either Altadena or (the full plan on proposed on-street truck routes can be viewed here).

At a , county officials said their preference would be to haul the dirt down Windsor Avenue to the 210 Freeway, despite a groundswell of opposition from Altadena residents.

The on-site storage option would have cut that traffic down drastically, with 80 percent of the sediment remaining on a field in Hahamongna. But after Pasadena city officials originally scheduled discussion of the on-site storage plan for Monday's City Council meeting, it has now been removed from the agenda, according to Dan Rix, the city engineer.

Rix said that public comment from several speakers at last Monday's meeting against the on-site storage plan has convinced officials they can't figure out if the plan is legal under state environmental laws in time to comply with the county's desired start date.

"We don't believe we'll be able to figure out all the issues," Rix said.

The site for the storage would have been Johnson Field, a one-time softball field that is now open space.  In rainy winters, a seasonal lake sometimes forms in the area.

Several people spoke at Monday's meeting against inundating the field with mud and sediment, with one commenter referring to frogs in the area "screaming and dying as mud is dropped on them."

Without permission from the City of Pasadena, the county will not be able to use Johnson Field, according to Bob Spencer, a spokesman for the County Public Works Department.

But while department officials did request Pasadena's permission to use Johnson Field, the department had never made the decision to chose the on-site storage plan, Spencer said.

Though work is supposed to begin in July, Spencer said no decision has been made on a route, and the department may still need to file for permits for any hauling alternatives.

The current discussion over dam clean-out is just the beginning of dealing with the issue.  In the long term, the department will need to remove roughly 2 million cubic yards of dirt from the dam over several years.

The full plan, which involves removing dozens of acres of mature black willow trees, require a full environmental impact report (EIR), a step county officials had originally hoped to bypass.  The County Board of Supervisors after local wildlife and open space advocates objected to the plan.