Just weeks after Bitcoin’s third halving cut block rewards from 12.5 BTC to 6.25 BTC, the network’s hashrate has staged a remarkable recovery — and the annual Sichuan hydro season is playing a central role. As cheap, abundant hydropower comes online in China’s southwest, miners who survived the halving are ramping up operations, pushing the network hashrate back above 120 exahashes per second (EH/s) by early July 2020.
TL;DR
- Bitcoin’s hashrate recovered above 120 EH/s by early July 2020 despite the May 11 halving cutting miner revenue in half
- Sichuan’s annual rainy season brought cheap hydropower online, fueling what industry observers call the “Great Migration” of mining equipment
- Network difficulty reached 17.35 trillion on July 13 — an all-time high — after a 9.8% upward adjustment
- 16 mining pools compete for blocks, with F2pool leading at roughly 16% of total hashrate
- Miners who weathered the halving and Black Thursday are now operating in a more competitive landscape than ever
The Halving Shakeout
When Bitcoin’s block reward was halved on May 11, 2020, the immediate impact on mining operations was significant. The top 10 mining pools saw their combined hashrate drop by approximately 18 EH/s on halving day, falling from around 120 EH/s to roughly 100 EH/s. In the first 24 hours of the 6.25 BTC epoch, only 137 blocks were mined — below the expected 144 — suggesting many miners were caught off guard by the new economics.
For marginal operations running older ASIC hardware, the halving was the final straw. With revenue cut in half overnight and Bitcoin trading around $9,100, many smaller miners were forced to shut down their machines entirely. Some waited for the next difficulty adjustment to restore profitability; others simply exited the market.
The Great Migration Begins
But even as some miners capitulated, a larger seasonal shift was underway. Each year, mining operations in China undertake what has become known as the “Great Migration” — physically relocating thousands of ASIC machines to Sichuan province to take advantage of the rainy season, which runs from roughly May through October.
During this period, abundant rainfall generates massive amounts of cheap hydroelectric power. Electricity costs — the single largest expense for any mining operation — can drop significantly, turning previously unprofitable mining rigs into viable money-makers even at post-halving Bitcoin prices.
The timing in 2020 was particularly critical. Coming just weeks after the halving, the arrival of cheap Sichuan hydropower provided a lifeline for miners navigating the new 6.25 BTC reward era. Operations that had been barely profitable suddenly found themselves with breathing room, and the network began to reflect this renewed activity.
Hashrate Recovery Tells the Story
By early July 2020, the numbers spoke volumes. The Bitcoin network hashrate had not only recovered its post-halving losses but surged past the 120 EH/s mark — a level that many had considered optimistic given the recent reward reduction. According to data from Blockchain.com and Fork.lol, the hashrate remained consistently above this threshold throughout the first week of July.
This recovery was remarkable when viewed against the backdrop of the previous months. On Black Thursday, March 12, when Bitcoin crashed to $3,800, the hashrate had plummeted from approximately 124 EH/s to 95 EH/s — a 23% decline. The fact that by July the network had not only recovered but was pushing toward new highs demonstrated the resilience of Bitcoin’s mining infrastructure.
Difficulty Reaches Record Highs
The rising hashrate triggered a corresponding increase in mining difficulty. On July 13, 2020, the network difficulty jumped 9.8% to reach 17.35 trillion — the highest level in Bitcoin’s history at that point. This followed an even larger adjustment of 14.95% on June 16, which had pushed difficulty to 15.78 trillion.
These back-to-back upward adjustments confirmed that miners were returning to the network in force, driven by the favorable economics of the Sichuan hydro season. The 16 active mining pools were competing more intensely than ever, with F2pool commanding approximately 16% of the network’s total hashrate, followed by Poolin at slightly over 15%, and Btc.com, Antpool, and Huobi each controlling roughly 10% or more.
Network Security Strengthened
For Bitcoin holders and users, the mining recovery carried an important implication: network security was strengthening. The hash power securing the blockchain had never been higher, making it increasingly expensive and impractical for any attacker to attempt a 51% attack. The difficulty adjustments — a core feature of Bitcoin’s self-regulating protocol — ensured that block times remained close to the target of 10 minutes despite the influx of new mining power.
The self-correcting nature of Bitcoin’s difficulty algorithm was on full display. When miners shut down after the halving, difficulty dropped, making it easier for remaining miners to find blocks. As the Sichuan hydro season brought new power online, hashrate rose, difficulty followed, and the network maintained its steady cadence of block production.
Why This Matters
The early July 2020 mining landscape offered a real-time demonstration of Bitcoin’s economic security model in action. The halving was supposed to devastate miners — and it did force out the weakest operators. But the protocol’s difficulty adjustments, combined with natural market forces like seasonal hydropower availability, ensured that the network not only survived but grew stronger.
This cycle — miner capitulation followed by recovery and growth — would repeat itself in future halvings, but the July 2020 episode remains one of the clearest examples of how Bitcoin’s incentive structure creates a self-healing system. The miners who adapted to the new reality of 6.25 BTC blocks were rewarded with a network that was more secure and more decentralized than ever.
Disclaimer: This article is for informational purposes only and does not constitute financial advice. Bitcoin mining involves significant capital expenditure and operational risk. Always conduct your own research before making investment decisions.
Sichuan hydro stations needed miners as much as miners needed cheap power. curtailed energy during rainy season was literally being wasted before crypto showed up. mutual symbiosis not parasitism
hydro_spill_ the curtailed energy angle is what nobody gets. sichuan dams were literally spilling water because they had excess capacity. miners turned waste into revenue
17.35T difficulty was an ATH back then and people thought mining was centralized. fast forward to 2024 and Foundry + AntPool control over 50%
Jonas Holt Foundry+AntPool at 50% is crazy. We had way more pools back in 2019 before the big ops took over.
Jonas Holt 17.35T felt centralized in 2020 with f2pool at 16%. Foundry at 30% in 2024 made that look like a golden age of distribution
difficulty at 17.35T was an ATH back then. now its over 110T. the fact that S19s from that era are still running at a profit in 2026 shows how far efficiency has come
Wenjin Z. S19s surviving this long is actually crazy. a 2020 ASIC still profitable in 2026 is unprecedented. every previous generation was paperweight within 2 years
the halving cut rewards from 12.5 to 6.25 BTC and miners just packed up and moved to cheaper hydro. speaks volumes about how adaptable the mining sector was even in 2020
sichuan hydro season was the backbone of btc mining for years. difficulty at 17.35T was a record then, now its over 80T
people wonder why china eventually cracked down. miners consuming entire hydro provinces was never gonna last
the crackdown was inevitable. china was never going to let a decentralized currency consume their energy surplus indefinitely
hydro_miner_ the rainy season migration was insane. trucks full of Antminers driving to abandoned hydro stations next to dams in Sichuan. peak bitcoin era
Garik S. my cousin ran a farm near Ertan Dam in 2019. trucks full of S9s showing up at 3am, negotiating electricity rates directly with station managers. wild west energy
dam_operator_ negotiating electricity rates directly with station managers at 3am was standard practice. the hydro stations needed the demand as much as miners needed cheap power
Garik S. I ran 200 S9s in Sichuan during the hydro season. Cheap power but the rainy season floods were brutal.
17.35T seems cute now but that was the peak of a different era. the migration to sichuan was pure arbitrage, miners followed the cheapest electrons
the great migration of mining equipment to sichuan every rainy season was such a uniquely chinese mining phenomenon
16 pools competing and f2pool at 16%. compare that to the current mining landscape where its far more concentrated
f2pool at 16% with 16 pools competing felt concentrated. now Foundry alone controls 30%. mining went backwards on decentralization
f2pool at 16% was the most decentralized mining ever got. now Foundry and AntPool control over 50% combined
pool_math_ f2pool at 16% with 16 pools competing. now Foundry alone controls ~30%. mining got more centralized not less
f2pool was 16% and that felt concentrated. now foundry alone is 27%. decentralization went backwards hard
difficulty at 17.35T was an ATH back then. now its what, 110T+? the hardware efficiency gains barely keep up with the hash growth
17.35T difficulty was an ATH then. now its over 100T and people still romanticize the Sichuan hydro era. the China ban was inevitable
Post-halving Sichuan ops are moving to solar because hydro alone can’t cover the new difficulty. Green mining push is real.
S19s still profitable in 2026 is the real headline. previous gen ASICs were e-waste within 24 months. bitmain actually built something that lasted