Sonora, CA — By mid-June a local water district anticipates releasing for public review an environmental document supporting its multi-million dollar preservation and restoration plans for Phoenix Lake.
The opening of the public comment period is expected to pave the way for a public hearing by late July and trigger more meetings with members of the homeowners’ associations around the lake.
Although the project, if it moves forward as scheduled, is not slated to begin until next spring, it will involve extensive work over a two-year period. While no impacts to local drinking water supplies are expected, related activities will effectively take the lake out of recreational play for two summers.
Tuolumne Utilities District (TUD) District Engineer Erik Johnson, interviewed by Clarke Broadcasting to provide an overview of the project, traces Phoenix Lake’s roots back to 1852, when its purpose was to support local mining operations. “Like so much of our water system with the ditches…and flumes, it was for the gold,” he recounts. Over time, it became a recreational asset.
A Primary Though Murky Water Supply
Subsequent development around it and upstream on the 25-mile area watershed led Phoenix Lake’s conversion to become the primary water supply for Sonora, Jamestown and areas like Mono Village and East Sonora. It also begat a sediment inflow increase and buildups within the lake from erosive soils and decomposed granites that now exceeds more than 20 times of what it was before all the development.
Among the set goals are to increase water storage in the reservoir by roughly a third to 850 acre-feet and to improve water quality. Johnson points to invasive aquatic growths such as Eurasian milfoil. Native to Europe, Asia, Europe, North Africa, it covers portions of the lake like a carpet, choking off oxygen levels and contributing to “off” tastes and odors in the drinking water. “We can chlorinate it and it is safe to drink but when the water temperature is high you can taste it,” he confides.
Too, he comments, “The circulation in the lake is bad. Water from Sullivan or Power creeks through the lake to the pipeline into the water treatment plant does not circulate well, creating stagnant areas such as at the side of the lake near Phoenix Lake Road.”
While watershed was dredged twice in the 1980s — once by PG&E and once by the county — those operations were done by sucking and scooping sediments while leaving the lake water in the basin. Outlining the district’s plans, Johnson explains, “We are hoping to actually drain portions of the lake in two phases…literally drain half the lake and then literally get equipment into the lake bed and dredge – excavate – all that sediment, and then remove it– So we know exactly what we are removing…how much…and how deep [the lake] is going to be in certain areas.”
Sandbars For Improved Circulation
Following that, he says, “We will reestablish sandbars in a very specific pattern so that the water, as it comes in from Power and Sullivan creeks, goes into what I call the the south side of the lake where Phoenix Lake Road is, and then doubles back and heads towards the pipeline that goes over to the water treatment plant.”
The resulting circulation pattern is expected to help keep water temperatures down and facilitate a deeper lake where sunlight will not permeate, which will help discourage invasive aquatic growth and improve dissolved oxygen levels. In another step within the project, TUD has slated to abate excessive lake reed root mats, timed with TUD’s Division of Safety of Dams permit requirement to lower the lake levels in November by about six feet, enabling room for winter storm flows. During the drought one reedy area actually caught fire, showing that these overgrowths are a potential fire hazard.
Addressing concerns of those who might think that the dredging will have to be completely redone at some later time, Johnson explains that TUD will be installing a large sediment capture basin at the inlet where Sullivan, Chicken and Power creeks come together. “That will be where all of this material settles out…so we will be able to lower the lake in that area every five years or so and clean it out [there] and not have that sediment scattered throughout the whole lake, which makes for a really expensive project.” Cleaning out the sediment forebay when it comes time he says, will likely create only nominal impacts.
‘Tapping’ Cost Savings From Indigeny Reserve
Overall funding for the project includes $5 million from two separate grant allocations through Prop 84 administered through the obviously supportive Integrated Regional Water Management Agency (IRWRMA) and a contribution of $1.1 million from the district. Design and permitting costs at $770,000 will leave the balance for construction.
Johnson shares while it is possible those costs might not allow the district to accomplish quite everything it wants, the district is encouraged by some major cost savings obtained through an agreement with Cedar Ridge Apple Ranch/Indigeny Reserve to accommodate the sediment deposits — which have tested out as not presenting a health hazard — on their ranch land adjacent to the lake for a fraction of the cost it would be to haul it out and deposit some distance away.
Come next April, if the project initiates without any delays, Johnson says that residents around the Phoenix Lake will not see it begin to rise as it typically does that time of year. “Instead of the reservoir going up by six feet when we put the boards in at the dam and raise the level, we will actually initiate a lowering of the reservoir and it will look very different than people have ever seen the lake…and it will be that way throughout the summer next year,” he explains.
Addressing Customer Impacts
“Those living around the lake will notice because they will not have recreational lake access. There will be some noise, but the equipment will not be located next door to houses and we are going to protect peoples’ docks,” Johnson maintains. Although the bulk of the work will be done over next summer, he allows that current plans call for the reservoir to be lowered again in 2019 to complete the project.
Johnson emphasizes that when construction is underway part of the lake will continue being maintained as a drinking supply and a fish refuge, so Sonora residents and businesses might not even notice anything is going on. As an aside however, he notes, “Our treatment plant operators are going to have to keep a really close eye on water quality and they will need to change the way they filter and chlorinate the water.”
As far as anticipation of public comments ahead go, Johnson replies, “I imagine once the [environmental] document is out there will be some comments — I have not heard a whole lot of concern about recreation.”
By and large, he says, the community has been very supportive and the people living around the lake realize it needs to be improved. “Anyone who has a dock and that lake is in their backyard is going to see a much improved lake,” he states. Admittedly he adds, “But it is going to come at the cost of two summers. So we are hoping that people will stomach it and work with us through the project.”
Benefits Include Preserving Emergency Provisions
Summarizing, Johnson opines, “I think it is a great project that incorporates a lot of benefits…recreationally, environmentally, drinking water, water supply.” Too, he points out, “If a big fire came through the area and wiped out the flume below Lyons Dam, it would be Phoenix Reservoir that keeps the business community…everybody in town in water for 30 days or more while a repair is made on the upstream system — so it is really an emergency water supply as well.”
While the overall project provides some major fixes, he says the district realizes that it needs to be coupled down the line with other improvements in the watershed, such as road culvert repairs and the construction of smaller upstream basins to collect some of sediment down-flow.
Johnson remarks this will require coordinating with potentially hundreds of property owners and the county. So, for now, he chuckles, “Our game plan is to address the lake…and phase in — over time — repairing the scars that are throughout the watershed upstream.”
To view historic and current images of Phoenix Lake as well as project-related illustrations, click into the image box slideshow. For more project details, click here.