Pima County officials are going to ask the Board of Supervisors to approve $1.5 million for a drainage improvement project originally requested by the city of Tucson.

The Pima County Flood Control District will foot the bill after officials say the city declined to share any of the costs for a box culvert drainage structure for the High School Wash project, near Tucson High School.

The High School Wash project is the final phase of the 20-year-long Arroyo Chico flood control project, which was undertaken to alleviate flooding issues in neighborhoods in the east and central areas of Tucson.

Local governments have been working on the project with the U.S. Army Corps of Engineers.

The county will also ask the board for approval to seek reimbursement costs from the Regional Transportation Authority.

In light of the city’s refusal to share in the cost after the price escalated from $140,000 to more than ten times that, County Administrator Chuck Huckelberry will also ask the board to approve a measure requiring a legally enforceable contract before entering into any agreements with the city.

This is the latest in a string of disagreements between the city and the county over downtown infrastructure improvements. In the past year, the two governments have clashed over costs for the new downtown courts building, relocation costs for water and sewer lines, and the widening of East Broadway.

Work on the High School Wash box culvert being done at the city’s request accounts for about $1.2 million of the cost. Work benefiting the county amounts to $610,000, with the federal government contributing $3 million.

In the original agreement, the county said it would cover the city share, when it thought the project would cost less, according to county officials.

However, the cost escalated when the scope of the project changed.

The county will use $1.5 million of flood control district money set aside for construction costs to pay for the city share of the work and to create a $300,000 contingency fund in case costs increase further, Huckelberry said.

The city has already contributed to an earlier phase of the High School Wash project by paying for multiple drainage improvements associated with the Regional Transportation Authority-funded Downtown Links project, which will benefit High School Wash, according to a letter Assistant City Manager Albert Elias sent to the county on April 25.

Those projects include a drainage project along East Eighth Street and a storm drain on East Seventh Street, both near High School Wash, Elias said in the letter. City officials declined to comment Monday.

The county flood control district decided to move forward with the project despite the funding dispute because it will lose the federal money if it doesn’t begin the next phase, Huckelberry said.

“To increase our share almost twice what it was before is difficult but necessary,” he said. “Our view is it’s best to finish this project and get it done, once and for all.”

The box culvert was already a part of the project, but city officials asked for improvements to the structure last July to address flooding concerns in the North Fourth Avenue shopping area, according city and county documents.

City officials wanted to increase the size of the box culvert from 8 by 10 feet to 10 by 12 feet, build a series of storm drains near the structure and make other improvements.

The county flood control district agreed to pay for the improvements after city officials said it would cost $140,000. However, the Army Corp of Engineers obtained an updated cost estimate of $1.2 million for the box culvert last year from a project contractor.

The higher cost is mostly due to the work needed to build a larger box culvert, Huckelberry said.

Contact reporter Jamar Younger at jyounger@azstarnet.com or 573-4242. On Twitter @JamarYounger