Energy and water rates on Guam are set to go up by as much nine per cent from Friday, February 1.
The Public Utilities Commission approved the rate hikes at a meeting Tuesday night.
Utility prices already tend to be higher in most Pacific countries and territories compared to the US mainland and other industrialised countries.
But a lawyer for Guam's Public Utilities Commission, Fred Horecky, has the water rate did not rise as much as originally expected.
"The water rate, which ultimately was increased ... 6.10% but on a compressed basis ended up being for the rest of the fiscal year, 9.15%.
"But actually, the 6.10% increase was less than the originally approved 8% so I guess an optimistic way to look at [it ]was in fact it [was] not as much as originally expected, so that's perhaps good news."
But he said there may be more increases to come.
" ... it was approved by the Commission that by March of this year, the Utility will provide the Commission with its next five-year rate plan, so unfortunately if I had to predict, I would say that a number of additional rate increases will likely be required on the water side."
Mr Horecky says the water rate increases are for the water utility's revenue and not to improve the water system, for which they have a separate 'system-development' charge, paid by developers when new developments are made.
But he told Pacific Beat families are already struggling with high utility costs.
" [At public] hearings, we have heard a number of the poor people in the community, I guess - some have to turn off their air-conditioning for example, reduce power usage, so there is an impact, and I know the rates are high and some people certainly cannot afford them."
Mr Horecky said the increase in electricity rates is mainly due to fuel costs.
"... on our power bills in Guam, likely 70% - 80% of the rate is fuel oil - our generators are at this point almost all fuel-driven, although there have been a few new alternative energy, solar and wind projects, so unfortunately the power authority is stuck with the fuel price and [this] is passed through to the customers."