Zcash Set to Freeze $16 Million Across Its Longest-Running Privacy Pool

Roughly 12,200 ZEC still sits in Sprout, the initial privacy pool Zcash introduced back in 2016. While around 10,000 coins were withdrawn over the past week, a mere 40 or so moved out on Wednesday.

Investors holding Zcash have less than 24 hours to clear roughly $16 million from the network’s original privacy pool. Once the incoming upgrade takes effect, any remaining coins will be rendered unspendable—even if owners retain their private keys.

As of Thursday morning, around 12,226 ZEC stayed inside the network’s Sprout pool, dropping from nearly 22,263 the prior week based on ZecStats historical data. The bulk of this drain was triggered on Sunday when nearly 9,094 ZEC exited, followed by a trickle of just 40 ZEC on Wednesday.

Zcash’s NU7 Upgrade Will Make Sprout Pool Funds Permanently Unspendable#

The Zcash network enables users to conceal transaction amounts alongside sender and receiver identities. These private balances live in shielded pools—essentially distinct blockchain compartments operating on different software generations of privacy tech. Sprout was rolled out at the network’s launch in October 2016, though it has since been replaced by newer pools.

The cutoff is set to hit alongside NU7, a network upgrade scheduled for block 3,543,405.

Blockchair data shows the blockchain reached block 3,542,391 at 05:24 UTC Thursday. With target times set at one block every 75 seconds, around 21 hours remain, putting activation right near 9:30 p.m. ET Thursday.

The exact timing relies on how quickly miners discover new blocks, meaning the upgrade could be pushed into early Asian business hours on Friday.

Version-4 transactions—the sole format capable of spending Sprout funds—will be rejected under NU7, according to the ZIP 2003 specification outlining the change. Once these new rules kick in, any balance left inside the pool becomes permanently unspendable.

With ZEC priced around $1,300, the leftover balance comes out to roughly $16 million, though ongoing withdrawals leading up to activation will likely shrink the total amount being locked up.

The public pool balance reveals neither the owners’ identities nor how much crypto is trapped in lost wallets. Sprout addresses start with “zc”—a key detail that helps people scanning old wallet records spot whether this deadline impacts them.

These tokens will stay counted inside Zcash’s total circulating supply. While ZIP 2003 leaves the door open to restore access through a future network update, it explicitly warns that spending abilities might never be unlocked again.

Maintaining Sprout behind the scenes also demands ongoing resources. Despite the pool’s minimal traffic, its legacy transaction framework introduces added complexity and security risks into the software verifying Zcash payments, according to ZIP 2003.

NU7 also drops target block times from 75 seconds down to 25, shortening the expected waiting period before transactions get confirmed.