Take a quick look at the annual town reports for Tisbury and Oak Bluffs and it becomes immediately apparent why the towns have begun investigating the prospect of cutting back and/or merging their police departments.

They are extraordinarily expensive.

According to the table listing the earnings of town and school employees in the 2008 Tisbury report, the top earner in town was a police sergeant, who earned just under $110,000 that year. Of the top 20 on the table — all earning more than $80,000 — nine were police officers, including four patrolmen.

To be fair, it should be noted not all of that money came out of town coffers. The numbers also included extra money officers received for doing other details in their off-duty hours: things like directing traffic around utility work sites on the roads.

Even taking that out, though, Tisbury police were exceptionally well paid. Tisbury’s two sergeants each are at the top of their pay scales, earning $71,472.24 in base salary. They also got extra for longevity and educational incentives, providing one with an extra $9,646, and the other an extra $4,280.

A patrolman on the top of the scale — there were four — got $58,631.04. Two patrolmen also were topped up with another $7,913 for longevity and education.

All told, Tisbury’s 13 full time officers, 10 special or traffic officers and 16 other departmental employees cost the town $1.275 million, $1.15 million of it just in salaries.

Among all departments, only education ate up a bigger slice of the Tisbury budget than the police.

Oak Bluffs spent even more: $1.7 million.

Personnel board figures for annual compensation, excluding overtime, showed the chief there got well over $102,000. There also was a lieutenant earning more than $87,000, two sergeants earning $80,000-plus, three others earning $70,000-plus, and everyone else earning more than $60,000.

By way of comparison the median salary, nationwide, for a patrolman is $50,000. But the costs lie not only in the high wages of the officers. They also lie in the duplication of functions inherent in the way the Island has grown up as a place with six local governments. And that is a problem common to all functions of town government here, not just the police.

A report prepared by the state Department of Revenue (DOR) in 2006 for the town of Aquinnah noted that in financial year 2005, residents of Martha’s Vineyard paid almost twice as much for local government services as the state average.

“Islandwide,” the report said, “approximately $83 million was budgeted for FY 2005. In comparison to the statewide average of $2,800 being budgeted per person, Martha’s Vineyard averages $5,400 per person.”

Aquinnah requested the report because it wanted to explore another prospect for regionalization: town property assessors.

The DOR found “obvious” financial benefits in having a single Island assessor, and also suggested other benefits, including better data collection and more uniform determinations of property values.

But like most moves toward regionalizing various functions of government, which have come up regularly over the years, the idea went nowhere.

The prospect of two towns sharing a police force, however, has not been contemplated before.

“This is something entirely new,” said Tisbury selectman Geoghan Coogan. “I know a lot of people think we’ve looked at it before, a few years ago. We have not.

“When it came up before, it only came up in the context of sharing a chief. The two departments were going to remain separate.

“But having a chief who spent half his time in Vineyard Haven and half in Oak Bluffs didn’t make any sense.”

Mr. Coogan hastened to add that no one can yet be sure if a merger would make sense either. But both towns now are committed to a thorough investigation of it.

To crunch the numbers they have engaged a consultant, Robert Wasserman, who has previously undertaken several studies of the internal problems of the Tisbury police.

“We have nothing to determine if it’s good or bad right now,” said Mr. Coogan, “and it’s quite a bit of work to put all the numbers together.”

Cost is clearly one of the drivers of the move, particularly on the part of Oak Bluffs. The town is facing a $500,000 budget shortfall, and according to some reports, could cut $85,000 from the police department budget this year.

Tisbury has no such budgetary problems, but does have major problems with its police department, stretching back for many years.

In a 2001 report, Mr Wasserman found the department to be “dysfunctional at best.” In the past three years, the department has gone through three chiefs. The last one, John Cashin, launched an extraordinary attack on some members of the force before he left earlier this year, and also labeled the department dysfunctional.

Mr. Wasserman recently completed another review of the Tisbury police, commissioned in the wake of the departure of Chief Cashin, which the town has refused to release, but which raised the amalgamation option.

Mr. Coogan said he hoped to have the results of Mr. Wasserman’s study in two or three months.

But already there are skeptics about the benefits of the police amalgamation proposal in particular, and of regionalization in general.

Arthur Smadbeck, a longtime Edgartown selectman, is one.

“I think it’s a good idea for Oak Bluffs and Tisbury to think about it, but I am dubious about whether they’re really going to save money,” he said. He continued:

“A large command structure, I’m afraid, could cost more money. Each town has its own problems. In Edgartown, we have South Beach, the Fourth of July parade, our bars to deal with. O.B. has their bars, and so on.”

And the history of regional initiatives did not give much cause for hope.

“Look at the high school, which was the most successful example of regional effort,” Mr. Smadbeck said.

“The agreement was 54 years old, they had the funding formula down perfect, by student population; if you sent 20 per cent of the children to the school, you paid 20 per cent of the cost.

“Then, when the state offered an alternative funding model, which had one community paying more than another on a per-student basis, Oak Bluffs jumped right on it. And it cost Tisbury hundreds of thousands dollars.

“Tisbury sued Oak Bluffs. So now they’re suing them over one regional arrangement and talking about entering another one?”

Likewise, Mr. Smadbeck noted, the Island towns once had a regional waste disposal district. Then Oak Bluffs and Tisbury seceded from it, leaving Edgartown, which had allowed everyone else to use their landfill, out of pocket when it came time to cap that landfill.

Again, it ended in court.

“So it sounds good. But when you go back in history and look at the past experiences of the towns in some of these regional efforts, it’s been less than successful,” he said.

What about for the broader question raised by the Department of Revenue finding that local government on the Vineyard is twice as expensive, per capita, as it is elsewhere in Massachusetts?

Mr. Smadbeck doubted that the people who conducted that study were aware of the special circumstances of the Vineyard, with its huge seasonal population fluctuations.

“You can use statistics to say anything, but the reality is that we have a lot of people who ship in here and don’t get counted when they do the division.”

Island services, including police, must be tailored to the peak population, not the year-round population, he said.

He conceded a regional approach might make sense in some areas, such as assessors. But not police.

Such skepticism notwithstanding though, in tough economic times, the pressure is likely to continue for such rationalization of functions, said Tisbury town administrator John Bugbee.

“It’s a hot topic, for sure,” he said.

“Regionalization is up for discussion and we would consider any department.

“But it’s very, very complicated. You’ve got two sets of employees, each on different sets of contracts, each getting different pay scales. What happens to the budget of the lower paid town?

“There are a lot of challenges. That doesn’t mean we shouldn’t look at it.”