Final answer:
A breech, commonly spelled 'breach' in legal context, is a failure to fulfill the terms of a contract, particularly through 'Less than Substantial Performance'.
This occurs when a party’s performance is so inadequate that it defeats the purpose of the contract. The reference to stream conditions and velocity appears unrelated to the legal concept of breach.
Step-by-step explanation:
A breech, in a legal context, is typically a term used to describe a violation or infringement of a legal duty or agreement. In the case of contracts, a breech is more commonly referred to as a breach, and it constitutes a failure to perform the terms as agreed upon.
Specifically, the term 'Less than Substantial Performance' describes a situation where the party's performance falls significantly short of what was contracted for, thus constituting a breach of contract.
The standard applies when a party has failed to perform enough of their contractual obligations that the purpose of the contract is thwarted. This could range from failure to deliver goods or services, to not meeting quality specifications or completion deadlines.
It seems that there may have been an error in the question, confusing a term from contract law with another subject. The provided reference to a 'stream under these conditions' and the velocity of a stream does not directly relate to the concept of breach in law.
Therefore, the inquiry about a stream's conditions, velocity, and premises appears to be inconsistent with the initial question about contract law.