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The California Floods Are Not All Bad News

Tulare Lake formerly encompassed 700 square miles and may reach 1,000 in severely rainy conditions. It started diminishing in the late 1800s as irrigated agriculture gained root in adjacent territories, and it has been totally dry most of the time since the mid-twentieth century. However, not this spring. The lake has now regained more than 100 square miles, and with the majority of the record southern Sierra Nevada snowpack yet to melt, it’s certain to expand more.

Although the lakebed itself is lightly inhabited, subsidence caused by groundwater pumping has placed numerous villages along its eastern border (the largest by far being Corcoran, population 22,535) under jeopardy. Over the last three weeks, frantic levee construction has lowered the likelihood of a significant residential deluge, but it’s already too late for some outlying residences and dairy farms near the lake and the rivers that feed it.

The crops produced on the lakebed are mostly annuals like cotton and tomatoes, rather than permanent vineyards or orchards. It was last swamped to this magnitude in 1983, with the water remaining in some parts for two years. Farmers’ lost income was significant, with the US Army Corps of Engineers estimating $132 million ($400 million in 2023 currency) in agricultural losses in the four counties in the lake’s catchment. However, depending on who is counting, those four counties generated agricultural income of $25 billion to $30 billion in 2021, with the great majority coming from places that are unlikely to flood.

The main economic significance of this year’s deluge for what is known to water nerds as the Tulare Lake hydrologic region and to everyone else as the southern San Joaquin Valley is instead the opportunity it presents to postpone a reckoning from more than a century of pumping more water out of the ground than seeps back in and possibly even put the region’s ever-thirsty agricultural industry on a path to sustainability. During California’s last extraordinarily rainy spring five years ago, I wrote about similar difficulties. They haven’t completely vanished, but there has been some improvement. And, as the former farm editor of the Tulare Advance-Register (for about 13 months in 1988 and 1989), I’m not going to pass up another opportunity to write about the region that generates more farm revenue than any other in the United States and uses more water than all of California’s residential, commercial, and industrial users combined.

The aquatic endowments of the Tulare Lake basin extended well beyond the lake itself, as seen by the marshes highlighted in grey on the above 1873 map. When painter and naturalist John Woodhouse Audubon (son of John James) arrived in what he dubbed the Tulare Valley in November 1849, it was already sopping wet due to California’s regular rainy season. “During the dry season, this great plain may be travelled on,” he wrote, “but now numerous ponds and lakes exist, and the ground is in places, for miles, too boggy to ride over, so we were forced to skirt the hills.” Audubon came upon what he dubbed “the river of the lakes” near the north end of the basin, where the Tulare basin’s surplus water sloshed into the San Joaquin River, which carried it north into San Francisco Bay during particularly rainy years.

The area did not get much rain. Deserts are defined as areas with less than 10 inches (25 centimetres) of average annual precipitation. Since the late 1800s, Fresno, at the northern border of the Tulare Lake basin, has gotten an average of 11.5 inches of rain; Bakersfield, to the south, has averaged 6.5 inches. With the highest mountain peak in the continental US and eight of California’s ten tallest along its eastern boundary, the basin could bank on a massive, albeit unequal, supply of melting snow, virtually all of which remained rather than flowing out to sea.

Farmers began to dry out the lands and channel the water in the decades following Audubon’s visit, first to accommodate the cattle herds of San Francisco beef barons Miller and Lux, then to the wheat fields depicted in Frank Norris’s 1901 novel The Octopus, then cotton, and finally to today’s relative diversity of crops. The four counties of the basin — Fresno, Tulare, Kern, and Kings — will contribute 49% of California’s agricultural earnings in 2021 and likely approximately 5% of the national total. (2) The most recent national agricultural census for which the US Department of Agriculture has released results is from 2017, at the tail end of a terrible drought in California, and the Tulare basin counties, along with the four counties of the northern San Joaquin Valley, still occupied six of the top seven and eight of the top 18 in the US county rankings.

Grapes and milk were the region’s leading agricultural products in 2021, with almonds and pistachios being the significant gainers in previous decades.

Water channelled from the region’s four major rivers (from north to south: Kings, Kaweah, Tule, and Kern) supplies part of the supply required to grow all of this, although groundwater is the primary resource in all but the wettest years. The water table was so high in the early days that all one had to do was dig, and water would come spurting out of the earth. Farmers in the area began to employ gas and steam pumps by the 1890s, and the first electric pump was erected in 1900. Tulare Lake was nearly gone by mid-century, the water table was rapidly falling, and area farmers needed a water bailout, which they received in the 1950s from the federal Central Valley Project and in the 1960s from California’s State Water Project, both of which took water from wetter regions to the north and delivered it to the Tulare Lake basin.

Tulare Lake basin farmers have consumed an average of 10.8 million acre-feet of water each year to raise all those crops during the last two decades. An acre-foot equals 325,851 gallons, or 1.2 million litres, but a more appropriate comparison is to total applied water consumption in California by agricultural and urban (residential, commercial, and industrial) users, which averaged 42.2 million acre-feet during the same time. That’s correct: Agricultural users in the Tulare Lake watershed accounted for over a quarter of all human water usage in California, 27% higher than all urban users combined.

Perhaps more importantly, 10.8 million acre-feet of water is more than Tulare Lake basin farmers can now expect from the region’s rivers, a sustainable pace of groundwater extraction, and imports from points north — all of which have been hampered in recent decades by drought, increased demand from Southern California cities, and environmental regulations. According to the Public Policy Institute of California, groundwater overdraft in the San Joaquin Valley averages 2 million acre-feet per year. The Tulare basin accounts for almost two-thirds of that, with anticipated consequences like fast ground subsidence in areas of the region and the drying up of numerous wells.

The state legislature approved the Sustainable Groundwater Management Act in 2014, a bundle of measures aimed at finally ending overpumping. Overdraft-prone areas were obliged to establish groundwater sustainability agencies tasked with developing strategies to bring long-term groundwater consumption and supply into balance by 2042. It’s a very lengthy, conflict-ridden process, but speaking with veteran watcher Ellen Hanak, head of the PPIC Water Policy Centre, last week, I was startled by how positive she sounded. “There’s progress,” she said. “It’s just that it’s hard, and sometimes it’s two steps forward, one step back, or one step forward, two steps back.”

Maybe she isn’t that hopeful. Farmers in the Tulare Lake basin, on the other hand, reduced water consumption during previous droughts, mostly by fallowing less profitable land, and they are making progress this year in rebuilding groundwater supplies. Parts of the permeable Kern River “alluvial fan” west of Bakersfield have been exploited for groundwater replenishment for decades. Currently, the whole structure is submerged.

Smaller initiatives are underway across the Tulare Lake basin, aided by Governor Gavin Newsom’s March 10 executive order suspending most permission procedures for floodwater diversions meant to replenish groundwater. Tulare Lake’s return isn’t much assistance on this front; it was and is a lake in part because the land underneath it isn’t permeable. However, the combination of an extremely wet winter and spring, as well as the prospect of rules prohibiting farmers from pumping more water out of the ground than is replenished naturally and through human efforts, is bringing a lot of groundwater recharge experimentation, which should slow Tulare Lake’s growth. That, to me, sounds like development.

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