Last week, Tilden Park’s Jewel Lake was a dry meadow. After the weekend rainstorm, its watery glory was temporarily restored. In the long run, it’s shrinking.
Constructed in 1921, Jewel Lake suffers from a significant buildup in sediment from Wildcat Creek. The lake dam, originally meant in 1921 to catch water for human use, prevents fish like trout and salmonoids from migrating upstream. There are several schools of trout in the creek, but they are all located in different parts — some at Lake Anza, some at Jewel Lake, some elsewhere along the water. They don’t intermingle in part because of the dam that prevents upstream spawning.
Located near the Wildcat Canyon Trail and the Lower Packrat Trail of Tilden Park, the lake is on a trajectory to fill with sediment and become a sort of wetland-like area or meadow — and not just in drought years.
Four new concept plans commissioned by the East Bay Regional Park District show what might become of the lake.
With the most change-focused proposal from EBRPD, the lake would remain, and Wildcat Creek would be rerouted around it, aiding in fish migration — particularly rainbow trout. Other proposals would leave the lake to its fate, eliminate the lake by removing Jewel Dam or keep dredging the lake every couple decades. The difference between “do nothing” and the concept that routes the creek around the lake amounts to about $15 million.
The district paid two engineering firms $450,000 to study the lake and come up with the concepts. The money it would take to implement either of the new plans includes the initial engineering fees.
The lake has been dredged twice since 1921 – in 1967 and 1991. Without more dredging the lake will eventually fill.
“This is a concept where we do no action, essentially, and let nature take its course,” EPRPD civil engineer Scott Stoller said. Although work needs to be done to fix the land downstream from the dam, which has been scarred from the constant influx of water pouring over from the lake into the creek, accepting this concept means “sediment continues to settle into the lake and the lake becomes a wetland like where the boardwalk is.”
While a wetland would attract local and migratory birds, the fish would still be unable to travel the nearby waterways.
This project would cost about $2 million, which includes design and permitting, construction to fix the scar and annual maintenance.
The second concept for the creek is to keep dredging it, something that will likely have to be done every 20 to 25 years. Dredging activity can be done between breeding and nesting seasons, in one construction cycle, park district officials said. This option also creates a fishway on Wildcat Creek north of the lake, which would push the Wildcat Canyon Trail a bit up the hillside. The remaining dam would still prevent fish from swimming upstream.
It would cost up to $16 million, the majority of which would be earmarked for maintenance.
Restoring Wildcat Creek entirely is the third concept, which would essentially eliminate the lake by removing Jewel Dam. There would be a fishway, but the public would lose the trail that crosses the lake dam. A new boardwalk crossing the creek would be built. The land around what was the lake would repair itself, and habitat would grow around the restored creek.
Price tag? Up to $12 million, most of it construction and little of it maintenance.
The most expensive proposal is to dredge the lake once and create a bypass channel for fish and wildlife, similar to a natural creek, on the west side of Wildcat Canyon.
The nearly $17 million estimated price tag relies heavily on maintenance, mostly because seasonally, water with more sediment would be diverted into the stream while water with less sediment will go into the lake. The reduced sediment buildup means the lake would not need to be dredged again for 100 years.
Community weighs in
The four concepts being mulled over by EBRPD staff, the district board, and community members who are participating in ongoing workshops.
“We’re looking at this like, what if this were a blank slate?” Stoller said. “We could design a lake and have Wildcat Creek flow in its natural form. If we were to design Jewel Lake with the environmental protection ethos, what would that look like?”
About 70 members of the public attended an Oct. 20 meeting about the proposed changes, which appear to be on a rapid timeline for a decision by the EBRPD’s board of directors. Perhaps by the end of winter 2021-22 there will be a board executive review of a preferred design concept and a second public meeting. The concepts will be considered by the board and the one chosen will change Jewel Lake (or not), with design starting in spring 2022.
The concepts were first shown to the board in September. EBRPD staff fielded several questions about otters and beavers, dredging and, particularly, the resilience of the area in the era of climate change.
Otters and beavers will continue to make use of the area under each plan, as both mammals are resilient and can travel over land like city streets. Dredging will disrupt wildlife, but it can be done during times of the year with the least impact on wildlife as possible, park district staff said.
Very few of the attendees at the meeting preferred continuing the current course, and many expressed interest in restoring the creek and keeping the lake.
EBRPD staff have also consulted local tribes, including the Confederated Villages of Lisjan/Ohlone, whose native land is being talked about. Stoller said the Lisjan prefer an option that promotes fish migration and wildlife, either option No. 3 or 4.
An additional public meeting is planned in the coming months but has yet to be scheduled. Feedback on the concepts can be sent to Scott Stoller at firstname.lastname@example.org.
Correction: Design for the chosen concept will start in spring 2022. It’s still unknown when construction may begin.