Short Answer 
A comma splice occurs when two independent clauses are incorrectly joined by a comma without a conjunction. To correct it, you can use a semicolon, add a coordinating conjunction with a comma, or replace the comma with a period. The best correction for the given example is to use a semicolon: “The argument against constructing a new highway is compelling; it will disrupt local ecosystems and water tables.”
Step 1: Identify the Comma Splice
A comma splice occurs when two independent clauses are joined by a comma without a coordinating conjunction. For example, in the sentence “The argument against constructing a new highway is compelling, it will disrupt local ecosystems and water tables,” there is an incorrect use of the comma. Recognizing this error is the first step in correcting it.
Step 2: Choose a Correction Method
There are several effective methods to correct a comma splice. You can choose one of the following options:
- Use a semicolon to separate the two clauses.
- Add a coordinating conjunction (like ‘and’ or ‘but’) and place a comma before it.
- Replace the comma with a period to create two distinct sentences.
Step 3: Apply the Corrected Version
For the provided sentence, the best correction is: “The argument against constructing a new highway is compelling; it will disrupt local ecosystems and water tables.” This option maintains the relationship between the clauses while using the semicolon to correctly join them. It clearly communicates both ideas effectively.