Will the biggest snowpack since 1895 flood Fresno this spring? Not likely.
This story was originally published by Fresnoland, a nonprofit news organization.
In the southern Sierra Nevada, the biggest snowpack in a century is starting to melt. Over the next six months, according to the state’s projections, 6.8-million acre feet of snow is going to melt in the mountains above Fresno, flow down hillsides and coalesce into the San Joaquin and Kings Rivers.
As these rivers swell with snowmelt, is Fresno going to flood? Are Fresno homes going to be flooded like in Tulare and Kings counties? According to Peter Sanchez, Fresno’s top floodwater operator, the answer is no.
“Fresno’s uniquely situated between the San Joaquin and the Kings Rivers, and those rivers don't impact the Fresno area, even when the snow melts. Instead, they go around this metropolitan area,” said Sanchez, general manager at the Fresno Metropolitan Flood Control District.
The city’s major risk for flooding has already passed, Sanchez said. The only major flood headway in the city’s path -- from the low-altitude foothills -- tapered off its waterseason a few weeks ago. Over 40,000 acre-feet of floodwater was captured and diverted away by the flood district’s dams at Big Creek and Fancher Creek over the last few months, Sanchez told Fresnoland last week.
“If those [dams] were not there, during this year’s water season, all of Fresno would have been underwater,” Sanchez said.
This stormwater is going to be put to good use, he added.
“This should be a record year. This year is going to be an all-time record for our systems for groundwater recharging.”
Stanford’s mistake in Fresno
In 2023, Fresno avoided flooding with the help of 700 miles of pipelines, 153 water basins, and 10 dams. How that flood infrastructure got built is a 150-year story, as chronicled by a 1978 report by Todd A. Shallat, commissioned by the City of Fresno, Public Works Department.
The key lesson: out of the crucible of flood, the city of Fresno responded with more government.
In the 1870s, Fresno’s agricultural boom was fueled by irrigation ditches dug along the Kings River by Fresno’s early settlers. But the geology that made those ditches effective -- water flowing downhill -- also became Fresno’s biggest problem early on: flood.
In 1872, Leland Stanford, tasked with establishing where Fresno’s downtown would be located, originally wanted the city to be on the San Joaquin River. But Stanford became smitten with the 2,000-acre wheatfields, 10 miles south of the San Joaquin, that were owned by Moses Church, a midwestern Baptist.
Stanford, known back then as the dumbest of California’s four railroad barons, decided to locate Fresno next to Church’s three-year-old wheat and sheep operation, without realizing the future city was in the middle of a floodplain.
Stanford chose the spot in 1872, during a dry year, and the drainage area looked like an oasis. But the wheat fields Stanford was impressed with were so lush because they were at the bottom of a creek drainage area.
Only three years later, Stanford’s mistake to locate a city in the “sinks of Dry Creek” nearly ruined Fresno. In 1874, torrential rainfall hit the foothills above Fresno; chaos reigned, and the streets flooded. The town’s businessmen talked of suing Stanford. Fresno’s settlers began competing with each other by paving their own lots so that their rain puddles would drain into their neighbors’ tract.
But residents floundered on flood control for the next decade. It took an even bigger flood -- “Fresno’s Great Flood” -- to force residents to form an official city. In February 1884, “the floodgates of heaven were opened,” according to accounts in the Fresno Expositor, a local newspaper at the time, and Fresno was paralyzed for months. Even Stanford’s railroad couldn’t pass through Fresno.
But within a year, Fresno residents formed an official city government, and soon after, hired Ingvart Teilman, the city’s first flood engineer.
Soon, some of Fresno’s first taxes were used to grade streets to control stormwater.
More floods, more government
Fresno’s next big leap in flood control came after the floods of the 1930s and 1950s. In March of 1938, heavy rains caused Big Dry Creek to jump its riverbank, closing Clovis Unified schools for days and causing extensive flooding of the Fig Garden area.
Fig Garden’s flooding, ranging from one to four feet, damaged homes, eroded topsoil, and caused domestic water wells to be contaminated by overflowing septic tanks.
The flood spurred the U.S. Army Corps of Engineers to construct a 16,500 acre‐foot reservoir on Big Dry Creek, according to Fresno flood district’s official history.
The next flood, in 1955, generated even more government response.
After thousands of people were evacuated from their homes on Christmas Day of 1955, Fresno voters approved the formation of the Fresno flood control district, in June of 1956.
At the time, Fresno relied on low capacity sewers, canals, and dry wells to protect the city and its rapidly growing suburbs from floods.
But over the next 30 years, the city’s flood control district built a modern storm drain system: one complete with storm basins, underground pipelines, gargantuan water pumps, and dams along Fresno’s most troublesome creeks.
By the late 1990s, when this system was fully built out, FEMA took large areas of Fresno off their flood maps, according to the Fresno Metropolitan Flood Control District, meaning residents wouldn’t have to pay for flood insurance.
The flood district’s major achievement was to build big enough dams to eliminate Fresno’s 100-year floodplain, and protect Fresno from up to a so-called 200-year flood, which can happen every year with a .5% chance. A small pocket of Calwa is still susceptible to a 100-year flood, according to FEMA.
This protection happened primarily through the flood district’s partnership with the US Army Corps of Engineers, who ended up doubling the dam capacity at Big Dry Creek and built two new dams along Fancher and Redbank creeks. The floodwaters, via the flood district’s water pipelines, ended up in over 150 storm basins across the city.
2023 will be record groundwater recharge year
Fresno’s major flood control infrastructure is now complete. But flood waters still remain at the forefront of the urban area’s biggest government initiatives. Today, record flood waters are allowing Fresno to mitigate the impacts caused by climate change, which are causing bigger floods and drier droughts.
California’s drought, worsened by climate change, has reduced snowmelt deliveries to local farms, causing industrial agriculture to drill deeper wells into the valley’s underground aquifer, which, now over-drafted, is required by state law to be filled back up.
The Fresno flood control district is expecting its facilities to set a record for groundwater recharge. A huge part of why this will happen is the flood district’s heavy use of urban stormwater basins, which are not seen much anywhere else in the country, according to Brent Sunamato, a district engineer with the Fresno flood district.
“You just don’t find many systems in the country that use urban stormwater systems like we do,” which allow for groundwater recharge, said Sunamato in a flood district video last year.
Using the stormwater recharge basin, Fresno flood control district’s Sanchez said there will be a record amount of stormwater that percolates into Fresno’s underground aquifer. The current record stands at 45,000 acre feet. Sanchez said they will exceed it, but not past 100,000 acre feet - about a tenth of the capacity of Pine Flat Lake.
Another Kings River water user, the Fresno Irrigation District, is expecting a record recharge year.
“We're thinking with this big of a water year, we might be able to recharge as much as 200,000 acre feet of water,” said Bill Stretch, general manager of the Fresno Irrigation District.
This spring, with record snowmelt dumping through one of the world’s most engineered river systems, it’s open season on recharging the underground aquifers, said Steve Haugen, watermaster for Kings River Water Association, which delivers Kings River water for the Fresno Metropolitan Flood Control District to use for groundwater recharge. The Fresno flood district can recharge as much water as they want, Haugen said.
“At the current moment, they can get what they want. On a big year like this, they will be able to run a very extensive [recharge] season.”
This article first appeared on Fresnoland and is republished here under a Creative Commons license.