Initial Meeting on July 20th
On July 20, Public Works staff met with representatives from the County, Regional Water Quality Control Board, Army Corps of Engineers, Department of Fish & Game and the Audubon Society to discuss eradication and control of the Sago Pond Weed (http://aquaplant.tamu.edu/plant-identification/alphabetical-index/sago-pondweed/)that has established at foothold at Scottsdale Pond.
Staff noted that there are several options available to address this invasive species, but each has drawbacks. The list of options includes: draining the pond and excavating, mechanical raking, pond water coloration, stocking with triploid carp and chemical treatments. Based on staff’s research on the effectiveness of these options on eradication or control of this pond weed, staff made the recommendation to coordinate with the Marin-Sonoma Mosquito & Vector Control District to implement a chemical treatment program using a product called SonarOne; a non-toxic herbicide used for the management of aquatic vegetation in fresh water conditions. Due to the nature of the Sago Pond Weed, this option was accepted by the group.
Second Meeting on August 15th
A follow-up meeting of this group occurred on August 15 to visually inspect the conditions. Two other experts joined the group; UC Davis – USDA Agricultural Research (Exotic & Invasive Weed Unit) and the National Marin Fisheries Service. The group again concluded that the chemical treatment would be the most appropriate method for controlling the Sago Pond Weed.
Unfortunately, the experts noted that it is too late in the season to begin the treatment process, and they recommended that the City begin treatments immediately after the Spring rains end. In addition to the chemical treatments, it was recommended that the City stock the pond with triploid carp as they provide a very efficient long-term control strategy. The use of the triploid carp will require physical modifications to the storm drain outfall that feeds the pond to insure that the carp are not able to swim upstream into other habitat areas.
In addition to the Sago Pond Weed, the experts noted that the Cattails were advancing into the pond quickly and will likely begin taking over soon if left unchecked. While SonarOne does not impact the Cattails, the triploid carp will act as a controlling agent.
Community Outreach
In addition to these group meetings, staff has discussed the pond weed and fountain issues with both the Streetscape Coalition and representatives from the three Rotaries. No concerns were raised with the recommended course of action.
Purchase of New Materials
In anticipation of eradicating the Sago Pond Weed, staff purchased two new motors for the fountains at the pond. Due to the significant growth of the pond weed, the new motors will not be installed until after treatments have begun. This delay is precautionary as the pond weed could be pulled into the fountain motors and cause serious damage to the newly purchased equipment and we want to protect our investment to the best of our ability.
Permanent Repairs Planned for Next Year
Staff has turned on the original fountains and will make permanent repairs next Spring following the first round of chemical treatments.
