Denver teachers will begin a strike today after the negotiations with Denver Public Schools fell through over the weekend, the Denver Classroom Teachers Association told CNN on Saturday. Over the last 14 months, Denver Public Schools and the Denver Classroom Teachers Association had been attempting to negotiate the district’s compensation system, which is tied to the city of Denver’s turnover rate for teachers. According to the teacher’s union, teacher pay varies wildly from year to year because the district uses an unpredictable bonus system as a way to compensate teachers for a low base salary.

Some teachers say this low base salary has forced them to use unconventional means to save money, such as moving in with a friend and living in their basement, driving for ride-share companies such as Lyft, and working multiple jobs in order to supplement their income.

A large part of the reason why these teachers are having to resort to such means is that the city of Denver is an expensive place to live. As detailed by the Denver Channel, rent in Denver ranks as the 15th highest in the nation, which places the teachers who make anywhere between $30K and $45K in a tight financial bind. CNN Money also notes that Colorado is one of the most expensive states to live in America. Ismael Guerrero, director of the Denver Housing Authority told CNN, “Before we’ve realized it almost, we’re a high cost housing city… We’re new to that club, but we’re clearly there, because the wages haven’t kept up.”

As a result, the Denver teachers are striking for the first time in nearly 25 years. Henry Roman, president of the teachers union, told the Miami Herald, “We will strike Monday for our students and for our profession, and perhaps then DPS will get the message and return to the bargaining table with a serious proposal aimed at solving the teacher turnover crisis in Denver.”

But schools superintendent Susana Cordona told the Miami Herald that their proposal was fair enough to meet the demands of the union, “We presented an updated proposal that responds to what we heard from our teachers, aligns to our values of equity and retention… and significantly increases the base pay for all of our educators.”

As it currently stands, the school system in Denver stands to lose around $400,000 every day that teachers are on strike, and this has understandably gotten the attention of the Colorado Governor Jared Polis. Polis told the Miami Herald that he will not step in immediately, but he will if this situation does not improve.