Expand<\/a><\/p>\nThe first effort, the new diversion plumbing and framework for when flows can be pulled from the Eel into the Russian River, is further along. Sonoma Water expects to construct a new diversion tunnel as Cape Horn Dam comes down; the current tunnel will be made unusable at that time.<\/p>\n
\u201cWe are trying to coordinate with PG&E,\u201d said Sonoma Water Environmental Resources Manager David Manning. \u201cWe don\u2019t want to have a gap in time where we can\u2019t divert. We are very aware that any gap in time is akin to a \u2018no diversion\u2019 scenario. We want to minimize that.\u201d<\/p>\n
The diversions would occur only during high-flow periods, and max out at roughly 30,000 acre-feet annually. (An acre-foot is equivalent to the amount of water needed to flood most of a football field one foot deep, and can supply the needs of three water-efficient households for a year.)<\/p>\n
\u201cThe pumping rules lay out a schedule of how the flow can be diverted seasonally to protect the fish,\u201d Manning said.<\/p>\n
That new framework has alarmed farmers and residents along the upper Russian River, who are used to relying on year-round diversions from the Eel, and at historically higher annual average volumes.<\/p>\n
Manning, a longtime Sonoma Water official and fisheries biologist who now leads the newly formed Eel-Russian Project Authority, said while he understands concerns about the loss of dry-season diversions, the new waterworks and rules governing how they are used are the best option for a future without PG&E\u2019s equipment in place.<\/p>\n
Without the new waterworks, diversions would be \u201cabout half of what they currently are,\u201d he said. \u201cDiversions haven\u2019t been that low except in the very depths of the worst droughts.\u201d<\/p>\n
Many storage options to replace one<\/p>\n
Going forward, because year-round Eel River diversions are set to be phased out, expanded water storage is seen as critical by most interests who rely on those flows in Potter Valley and the upper Russian River watershed.<\/p>\n
Engineering teams, including outside experts hired by the IWPC, are in the early stages of exploring a range of options for Potter Valley, where irrigation supports about 2,300 acres of cropland.<\/p>\n
The engineers have pinpointed six options so far to replace between 30,000 and 60,000 acre-feet of water typically held in Lake Pillsbury.<\/p>\n
While none of the proposed options are a \u201csilver bullet,\u201d said Johnson, some could store more water than Potter Valley Irrigation District customers could use, providing benefits for customers downstream.<\/p>\n
![\"The](\"https:\/\/www.europesays.com\/us\/wp-content\/uploads\/2025\/11\/e3c2d25d-787a-5c94-82db-82b68be9f40d.jpg\")
<\/p>\n
Kent Porter \/ The Press Democrat<\/p>\n
The north end of Potter Valley in Mendocino County basks in sunlight on May 14, 2025. (Kent Porter \/ The Press Democrat)<\/p>\n
One concept \u2014 an enlarged network of storage ponds \u2014 is already in place in Potter Valley. Farmers have built 55 water storage ponds, capable of holding 775 acre-feet of water over 125 acres of land.<\/p>\n
Johnson estimates the valley needs at least 5,000 acre-feet of additional\u00a0storage capacity. To get there, storage ponds would need to cover another 500 acres, eventually accounting for 10% of valley floor space.<\/p>\n
The estimated cost for additional storage ponds ranges from $15 million to $28 million, which does not account for the cost of the distribution systems eventually needed to fill and drain the ponds.<\/p>\n
Another potential project for the valley would rely on storing more water underground in a method known as groundwater recharge. The number of wells in the valley would grow about five-fold to tap into the 3,500 acre feet of groundwater made available each year.<\/p>\n
That project could cost between $19 million and $22 million, plus the expense of more pipes to expand what\u2019s already in place, Johnson said.<\/p>\n
While grants and federal funding are available for both projects, much of the cost would likely go back to Potter Valley Irrigation District ratepayers. Potter Valley irrigators pay $35 (general delivery) per acre foot per year for water or $125 to $175 for so-called garden rate users, according to district documents.<\/p>\n
New dams to offset lost ones?<\/p>\n
Another option floated Monday is adding new storage \u2014 in the form of dams \u2014 along tributaries.<\/p>\n
Two streams within Potter Valley, Busch and Boyes creeks, could be candidates, according to Johnson, who said they would add storage equivalent to up to 25,000 acre feet.<\/p>\n
Another idea would involve carving a small reservoir, impounded by a new dam in the lower portion of Potter Valley, Johnson said. The reservoir could span about 60 to 640 acres, he said.<\/p>\n
Still, both options involving dams would be costly \u2014 running between $115 and $250 million \u2014 and highly difficult to permit, he added.<\/p>\n
Banking on Lake Mendocino<\/p>\n
Another option, Johnson said, would be to build a pump station and 10-mile pipeline extending north from Lake Mendocino to Potter Valley. The pipe project could be designed to divert 10,000 acre feet of water from Lake Mendocino to Potter Valley each year.<\/p>\n
Such projects are fairly straightforward from an engineering standpoint \u2014 Shapiro pointed to recycled water pipelines built in cities like Eureka and Healdsburg \u2014 but water rights could prove a sticking point.<\/p>\n
\u201cAll the current storage is fully subscribed,\u201d Johnson said of the supplies captured by Lake Mendocino. \u201cThat\u2019s a big problem.\u201d<\/p>\n
![\"Visitors](\"https:\/\/www.europesays.com\/us\/wp-content\/uploads\/2025\/11\/83e51648-5f65-5b97-90a5-ffc6e006d0c4.jpg\")
<\/p>\n
Beth Schlanker\/The Press Democrat<\/p>\n
Visitors walk across the top of Coyote Valley Dam as water is released down the spillway at Lake Mendocino near Ukiah, Calif., Monday, January 16, 2023. (Beth Schlanker\/The Press Democrat)<\/p>\n
That hurdle could be addressed by another concept already under federal study: raising the height of Coyote Dam, which impounds Lake Mendocino. That would allow the reservoir to store more supplies, possibly equivalent to the amount needed and controlled by Potter Valley irrigators.<\/p>\n
Key questions and concerns<\/p>\n
Monday\u2019s workshop prompted several overriding questions: How do such concepts move from the drawing board to execution? Who pays for them? And who stands to lose land, should that come to pass?<\/p>\n
Those unknowns spurred some in the audience to speak out, pressing key officials with their concerns.<\/p>\n
Johnson acknowledged the uncertainties still dominating the discussion. But, he added, now is the time to \u201cprioritize what is needed.\u201d<\/p>\n
Amie Windsor is the Community Journalism Team Lead with The Press Democrat. She can be reached at amie.windsor@pressdemocrat.com or 707-521-5218.<\/p>\n","protected":false},"excerpt":{"rendered":"The daunting question faced for years now by a small farming valley in Mendocino County is where it…\n","protected":false},"author":3,"featured_media":411220,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[23],"tags":[193374,193377,193378,746,193380,193376,193373,162662,193371,193372,193379,159,193375,193381,67,132,68],"class_list":{"0":"post-411219","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-environment","8":"tag-cape-horn-dam","9":"tag-coyote-dam","10":"tag-eel-river","11":"tag-environment","12":"tag-inland-water-and-power-commission","13":"tag-lake-mendocino","14":"tag-lake-pillsbury","15":"tag-pge","16":"tag-potter-valley","17":"tag-potter-valley-project","18":"tag-russian-river","19":"tag-science","20":"tag-scott-dam","21":"tag-sonoma-water","22":"tag-united-states","23":"tag-unitedstates","24":"tag-us"},"share_on_mastodon":{"url":"https:\/\/pubeurope.com\/@us\/115628969506745422","error":""},"_links":{"self":[{"href":"https:\/\/www.europesays.com\/us\/wp-json\/wp\/v2\/posts\/411219","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.europesays.com\/us\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.europesays.com\/us\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/us\/wp-json\/wp\/v2\/users\/3"}],"replies":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/us\/wp-json\/wp\/v2\/comments?post=411219"}],"version-history":[{"count":0,"href":"https:\/\/www.europesays.com\/us\/wp-json\/wp\/v2\/posts\/411219\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/us\/wp-json\/wp\/v2\/media\/411220"}],"wp:attachment":[{"href":"https:\/\/www.europesays.com\/us\/wp-json\/wp\/v2\/media?parent=411219"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.europesays.com\/us\/wp-json\/wp\/v2\/categories?post=411219"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.europesays.com\/us\/wp-json\/wp\/v2\/tags?post=411219"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}
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