You can't be blamed if you sometimes think environmental protection is not a high priority with the Reagan administration.

But whatever the president's policies, such tasks as purifying our water, monitoring air pollution and controlling pesticide use goes on at city, state and federal levels.

More than 1 million Americans make up the nation's environmental workforce, says the Labor Department, "and the size of the workforce is growing."

As a part of its continuing series of guides to the job market, the department has just released its 205-page Environmental Protection Careers Guidebook , outlining career possibilities in 106 different occupations.

Because environmental protection is a developing field, many of these occupations did not exist a decade ago. Around 40 of the, says Jules Spector, the occupational analyst who heads the guidebook program, have never been officially described before.

"Radiation Protection Engineer," says Spector, with Labor's Division of Occupational Analysis, is one such job. As it does with other occupations, the guidebook describes the job's responsibilities:

"Today, responsibility for radiation safety at a nuclear power generating plant rests with the radiation protection engineer, who supervises a number of chemical radiation technicians and is responsible for monitoring the chemistry, radio-chemistry, and radiation protection programs at a nuclear power plant. "

It states the job requirements. Among them:

"A bachelor's degree in chemistry or engineering and two years' experience in nuclear plant chemistry and radiation protection. "

When it comes to opportunities available, the guidebook tries, says Spector, to be as realistic as possible. While nuclear plant construction has made job possibilities in the field "excellent for the last few years . . .

"The prospect for growth and increase may not be as encouraging in the near future, however, as a result of the nuclear plant controversy."

Many environmental jobs are highly technical -- in such additional areas as noise control; land, fish and wildlife management; solid-waste management and industrial hygiene -- but others require only minimal schooling.

"Water-filter cleaner" in a municipal water treatment plant, says the guidebook, "is elemental work and requires no previous training. most employers probably prefer someone with an eighth-grade education, although less is sometimes sufficient."

The book includes such other jobs of widely varying skills as fish biologist, forester, landscape architect, air chemist, sewer maintenance worker, noise engineer, entomologist and refuse collection truck operator. Where applicable, college and other training programs available are given.

Since the guidebook program was revitalized in 1976, they have been coming out at a rate of two to four a year in two separate series, with several in the planning stages.

Their aim, says Spector, is to give job-hunters a "broad" and "realistic" picture of what's available in a career field. They are written to make them more "accessible" to young job hunters. Many career guides on the market, he believes, are "dense."

"When you talk to high-school kids, most don't understand the job market. They don't often have a realistic point of view. We try to present the information up front," so someone seeking a career can say, " 'This is what I want to do. This is how I go about it.' "

They fit right in, he feels, with the current administration's philosophy of "self-help" and "self-direction."

The Labor Department began publishing the two series, Spector says, when it realized: "We're a job-data gathering agency. We have all this information."

The environmental protection book, for example, he says "is special. There's no book comparable to this on the market." More than 170 public and private agencies contributed to it over a three-year period.

This latest guidebook comes in the series on broad occupational fields. An earlier guide dealt with careers in the health fields. The next, expected out this fall, covers jobs in criminal justice, from police detective to judge and prison warden.

Also under way is a guide to 80-90 jobs for high school graduates, in which "you do not necessarily have to go to college." And still another, says Spector, is Knowledge, College and Jobs , which will attempt to list career opportunities by college major.

"If you have a degree in English, where do you go? We'll give occupations that make heavy use of English majors."

The second series concentrates on career opportunities in specific industries, recently the telephone and telegraph industry and the trucking industry -- "two of the largest in the United States."

Last year, one guide was particularly successful, something of a surprise, says Spector, to its authors and editors: Career Opportunities in Art Museums, Zoos, and Other Interesting Places."We were getting 750 requests a week for it. There was an awful lot of material in it not available anyplace else. We filled a great vacuum."

Upcoming in three or four months is Career Opportunities in Hotels and Restaurants , particularly good, he says, for job hunters in big tourist cities such as Washington.

Spector's office also is busy on a job guide to the "highly significant" petroleum industry, "where there is a lot of employment." As with the other guides, much of the research is being done at 10 regional centers across the country. Staff members, in this case, have visited oil fields and talked to workers already on the job.

The guides generally are available for job-seekers and counselors at the 2,700 local Job Service offices throughout the United States affiliated with the U.S. Employment Service. Many public and school libraries also keep them on hand.