[env-trinity] SF Chronicle- Why water levels remain low at one major California reservoir, even after rain

Mon Apr 3 11:25:36 PDT 2023

Looks like that refill estimate below is based on Average Inflow, which likely relates to Average Snow (Water Equivalent) levels. So here's hoping the apparent Above Average SWE for April 1 (as noted on CDEC) will deliver above average inflow, and shorter refill time than projected below, but not too fast as temps finally warm up. [ https://cdec.water.ca.gov/reportapp/javareports?name=COURSES | https://cdec.water.ca.gov/reportapp/javareports?name=COURSES ] 

~Sari Sommarstrom 
Etna 

From: "Abel, Jennifer K" <jabel at usbr.gov> 
To: "Tom Stokely" <tgstoked at gmail.com>, "env-trinity" <env-trinity at mailman.dcn.org> 
Cc: "claire hao" <claire.hao at sfchronicle.com> 
Sent: Monday, April 3, 2023 9:43:41 AM 
Subject: Re: [env-trinity] [EXTERNAL] SF Chronicle- Why water levels remain low at one major California reservoir, even after rain 

Tom! It is so true! 

Check out these figures that the TRRP office put together in regard to inflow to Trinity vs other reservoirs in the California. 
It is interesting to see that Folsom Lake (on average) only takes 4.4 months to fill, vs Trinity at 22.3 months. I pasted the figures in the email below as well! 
[ https://www.trrp.net/restoration/flows/lake-conditions/ | TRRP: Lake Conditions ] 
[ https://www.trrp.net/restoration/flows/lake-conditions/ ] 

[ https://www.trrp.net/restoration/flows/lake-conditions/ | Trinity River Restoration Program (TRRP): Lake Conditions ] 
/ 
www.trrp.net 

Trinity Lake is a relatively large reservoir compared to the watershed that supplies it. Much of the water initially falls as snow in the surrounding mountains (including the Trinity Alps), which may not melt and flow to the reservoir until late spring or even summer. For this reason, Trinity is slow to fill relative to many other California reservoirs. The table below is a comparison of inflow to Trinity Lake versus several other major reservoirs. Reservoir 	Storage (af) 	Average Annual Inflow (af) 	Months to Fill at 
Average Inflow Rate 
[ https://www.usbr.gov/projects/index.php?id=266 | Trinity
 Lake ] 
	[ https://cdec.water.ca.gov/resapp/ResDetail?resid=CLE | 2,448,000 ] 
	1,320,000 	22.3 
[ https://www.usbr.gov/projects/index.php?id=241 | Shasta
 Lake ] 
	[ https://cdec.water.ca.gov/resapp/ResDetail?resid=SHA | 4,552,000 ] 
	5,630,000 	9.7 
[ https://water.ca.gov/Programs/State-Water-Project/SWP-Facilities/Oroville | Lake
 Oroville ] 
	[ https://cdec.water.ca.gov/resapp/ResDetail?resid=ORO | 3,500,000 ] 
	4,330,000 	9.7 
[ https://www.usbr.gov/projects/index.php?id=74 | Folsom
 Lake ] 
	[ https://cdec.water.ca.gov/resapp/ResDetail?resid=FOL | 977,000 ] 
	2,680,000 	4.4 
Cheers, 
Kiana Abel 

From: env-trinity <env-trinity-bounces at mailman.dcn.org> on behalf of Tom Stokely <tgstoked at gmail.com> 
Sent: Sunday, April 2, 2023 4:22 PM 
To: env-trinity at mailman.dcn.org <env-trinity at mailman.dcn.org> 
Cc: claire.hao at sfchronicle.com <claire.hao at sfchronicle.com> 
Subject: [EXTERNAL] [env-trinity] SF Chronicle- Why water levels remain low at one major California reservoir, even after rain 

This email has been received from outside of DOI - Use caution before clicking on links, opening attachments, or responding. 

While I'm sure some of the factors that the quoted people in this article talk about are true, they fail to recognize that Trinity Lake is twice the size of the average annual runoff, so refill is slow. 

TS 

[ https://gcc02.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.sfchronicle.com%2Fclimate%2Farticle%2Fcalifornia-drought-water-level-17872187.php&data=05%7C01%7Cjabel%40usbr.gov%7C7c0126383405490434e408db33d14c1b%7C0693b5ba4b184d7b9341f32f400a5494%7C0%7C0%7C638160746251244105%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=GyaQOpgIhxC7GA6TgTqYk37nlKVeGybAxWQgIzladns%3D&reserved=0 | https://www.sfchronicle.com/climate/article/california-drought-water-level-17872187.php ] 
Why water levels remain low at one major California 
reservoir, even after rain 
Claire Hao 
Updated: April 1, 2023 9 p.m. 

After an extraordinarily wet winter, most reservoirs in California are at, over or 
near their historical average capacity. 
But there’s a major exception: Trinity Lake, in far northern California, the third largest 
reservoir in California behind Shasta and Oroville reservoirs. Trinity is 
only at 51% of its historical average capacity — and 37% of capacity overall — as 
of April 1, according to data from the Department of Water Resources. 
Lewiston Dam is on the Trinity River, which has received less rainfall than other parts of the state. 

Trinity may be filling slower than other reservoirs because the northernmost 
part of the state has received less rainfall relative to other parts of the state, 
according to Jeffrey Mount, senior fellow with the Public Policy Institute of 
California Water Policy Center. 
Additionally, Trinity “is heavily dependent on snowpack; versus Shasta, which is 
mostly dependent on rainfall to fill,” Mary Lee Knecht, Bureau of Reclamation 
Region 10 public affairs officer, wrote in an email to the Chronicle. Much of the 
snowfall may not melt and flow into the reservoir until late spring or summer, 
according to the Trinity River Restoration Program. 
According to a closely watched map from the U.S. Drought Monitor, the 
northernmost parts of the state continue to remain in “moderate drought” in 
counties such as Siskiyou, Modoc, Lassen, Shasta and Trinity, with interior parts 
of Northern California also remaining “abnormally dry.” 
Gov. Gavin Newsom rolled back some drought restrictions last week but said he 
didn’t revoke his drought emergency proclamation because of persistent dryness 
in certain parts of the state. 
“It is incumbent upon us to recognize that the conditions have radically changed 
throughout the state, but not enough in places like Klamath and around the 
Colorado River Basin to call for the end of the drought in California,” Newsom 
said at a news conference last month. 
The parts of the state that remain dry are also usually arid areas: The northeast 
corner of California is known to be a rain shadow, whereas the southeast — 
where drought also persists — is desert, Mount said. The southeast corner of 
California also gets much of its precipitation from summertime monsoon rains 
instead of winter storms, Mount said. 
Inyo, San Bernardino, Imperial and Riverside counties remain in “moderate 
drought,” with parts of Inyo and San Bernardino counties in “severe drought,” 
according to the U.S. Drought Monitor. 
Most of the atmospheric rivers that hit California since December have been 
concentrated in the Bay Area and Central Coast, with some also hitting the Los 
Angeles region, Mount said, referring to a map of atmospheric rivers from the 
UC San Diego Institution of Oceanography. 
Few, however, have been directed at the Klamath Basin, with many landing just 
north or south of the region or brushing against it, Mount said. Trinity Lake is 
part of the Klamath Basin, with Trinity River being the largest tributary of the 
Klamath River. 
“For what you might call the luck of the draw, just enough of those atmospheric 
rivers shifted a couple hundred miles to the south this year rather than plowing 
into their normal location, which would be in the Trinity, Klamath watershed 
and Shasta and upper Sacramento. So we’ve got one of those years where we 
turned our normal gradient of precipitation — dry in the south, wet in the north 
— and flipped it so that our far north was not particularly wet,” Mount said. 
But even areas of California that on paper are out of drought will still feel the 
effects of long-term water supply problems. The Drought Monitor can be 
“notoriously unreliable” for California because it doesn’t take into account 
groundwater conditions — which have been slow to recover despite winter’s 
deluges — and the fact that California transports water across the state to meet 
local needs, according to Mount. 

Even if “the drought is largely over, water scarcity is enduring,” said Jay Lund, 
vice director of the UC Davis Center for Watershed Sciences. That remains true 
in the San Joaquin and Sacramento valleys, where it may take years for 
groundwater to recover from the overpumping during drought years. 
It also remains true in the Klamath Basin, where contentious debates about 
water use between agriculture and ecosystem preservation, which the drought 
exacerbated, won’t be alleviated soon, Lund said. 
“Tribes want to see lots of releases of water for salmon. Farmers are really seeing 
very little water from the projects because … of tremendous changes that are 
going to be occurring with the removal of some of the hydropower dams. It’s just 
a lively place for water conflicts,” Lund said. 
Why water levels remain low at one major California reservoir [ https://gcc02.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.sfchronicle.com%2Fclimate%2Farticle%2Fcalifornia-drought-water-le.&data=05%7C01%7Cjabel%40usbr.gov%7C7c0126383405490434e408db33d14c1b%7C0693b5ba4b184d7b9341f32f400a5494%7C0%7C0%7C638160746251244105%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=TdZ4EHnHUHTdLg%2BeGzLClSnURUflwEjfLL%2F1Z9pRddM%3D&reserved=0 | 
https://www.sfchronicle.com/climate/article/california-drought-water-le. ] .. 

To the south, in San Bernardino County, Heather Dyer, CEO of the San 
Bernardino Valley Municipal Water District, is not ready to declare the end of the 
drought either. The water district’s service area has received 56.9 inches this wet 
season, above the historical average of 31.1 inches, she said. 
Still, when looking at the pattern of rainfall over the past 20 years, this year’s 
above-average total hasn’t made up for the cumulative loss of precipitation the 
region has suffered since 1997, Dyer said. The district’s cumulative departure 
from the mean since then has trended downward, with wet years like this only 
marginally shifting the marker upward, she said. 
“To me, being in a drought is basically the cumulative amount of rain over time, 
and what that means to our ecosystems and our water systems,” Dyer said. “It’s 
going to take more than one wet year to get out of that hole.” 
In anticipation of future dry years, the San Bernardino Valley Municipal Water 
District is starting construction on a new stormwater capture project in April, 
which Dyer estimates will take 18 months to complete. 
“I wish we had that in place. I wish that many water agencies had those types of 
systems in place,” she said. “I feel like this has given me a new sense of urgency 
that we need to be building infrastructure for the future, and this year is exactly 
why we need to do that.” 
Reach Claire Hao: [ mailto:claire.hao at sfchronicle.com | claire.hao at sfchronicle.com ] ; Twitter: @clairehao_ 

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