Behind the networks' sudden surge of documentaries

If you've been wondering why there are so many commercial network documentaries scheduled for the end of April, don't make the mistake of attributing it to a suddenly surging sense of responsibility on the part of network programmers. Allow me to let you in on the secret of all this documentary dumping.

The end of April through the end of May is what is known in the industry as a ''sweeps'' period -- there are four such periods a year. During sweeps, the rating services focus on local stations, and the audience numbers for those periods are used as the basis for advertising rates in the coming period.

Since documentaries are notoriously low-audience shows, networks don't want to schedule a documentary in the sweeps period. But there has to be a certain amount of public-service broadcasting if stations are to retain their licenses when renewal time comes up, as it does periodically. Thus, instead of running documentaries in May, when they would bring the station rates down, the networks squeeze them into the earlier April schedule where they will do less harm, financially speaking.

That is why in this 10-day period there is an ABC News Closeup called Fortress Israel, a CBS Report on poverty, two NBC Reports on insurance and drugs , etc. Rejoice, if you are a documentary buff, because most of these documentaries are far superior fare to the regular series programming.

Meantime, on the other side of the dial, PBS goes merrily on its way, disregarding the commercial sweeps, offering viewers a wide selection of varied, vital, and often controversial documentaries as it does throughout the year. In the past few weeks there have been documentaries on Nicaragua and the Sahara which have caused great uproars because, some people claimed, they were too sympathetic to the leftists in both countries.

In the case of the Sahara documentary, the main focus of protest was directed toward excessive gore, although, perhaps, there may also have been a more political basis for the objection. The Sahara-Moroccan show, Blood and Sand: War in the Sahara, was rescheduled for showing on April 28 but has been shown already by some stations in its original time slot last week.

One hopes that the controversies will not be too discouraging for independent producers of documentaries and the PBS stations that have run them, since there is very little opportunity for independents to be heard on the commercial networks. It is unfortunate but true that controversy comes with the territory, since there is little legitimate PBS control over what an independent filmmaker wants to say unless it is outrageously tasteless and obviously un-airable.

This week several extraordinary documentaries are airing on PBS. It will be worth your while to seek them out, even if it means calling your local PBS station and asking for them, since many PBS affiliated stations schedule as they see fit. The days and times listed below are from the national PBS recommended schedule.

Pages of Testimony (PBS, Tuesday, 10-11 p.m.), originated on WTVJ, Miami, has rightfully won many awards already. The show, written and narrated by Mary Nissenson, tells of the incredible coincidence which, on the eve of her liberation, allowed Auschwitz survivor Lilly Jacob to find a photo album kept by one of Hitler's official photographers, who had secretly recorded the arrival at the camp of Lilly and her family as well as thousands of other Jews.

She carried the album with her for 40 years and finally decided to donate it to the famous Yad Veshem museum in Israel, since it is the only photographic record of concentration camp activities in existence. This deeply moving film then goes with Lilly to revisit Auschwitz.

Bad Moon Rising (PBS, Wednesday, 10-11 p.m.) is a KQED, San Francisco, production by award-winning TV journalist Stephen Talbot, who is determined to present the resurgence of ''the other side of America -- racism, anti-Semitism, bigotry.'' Especially frightening is the seemingly high level of sophistication he finds in the leadership of the Ku Klux Klan and other such organizations. This documentary pinpoints outrages which every American needs to be made aware of in order to fight against it. Public-service TV at its best.

Media Probes (PBS, an eight-part series starting Wednesday, 8-8:30 p.m.) is a highly ambitious, nearly totally successful series that attempts to investigate the communications media around us. Independent producers Kit Laybourne and Mickey Lemle are most successful when they forget gimmickry and reenactments and simply photograph the subject matter. Such topics as photography, soap operas, design, political spots, and language are handled with simple deftness by these young and innovative producers. Other topics are loaded down with tricks which tend to blur the focus. Although much of it masquerades as information, the series is pure entertainment. Sometimes it's as exciting as a ride on a roller coaster. But a roller coaster has its ups and downs.

Thinking Twice About Nuclear War (PBS, Friday, 10-11 p.m) is a production of Public Interest Video Network. The show, produced by Evelyn Messinger, narrated by Mike Farrell of M*A*S*H, for showing during Ground Zero Week (April 18-25), utilizes documentary portraits, animation, and historical film footage to analyze the variety of opinions as to how to prevent nuclear war. The film is an effective reminder that the taboo against even considering limited nuclear warfare has been broken -- now it is up to the people to reverse the movement toward ''thinking the unthinkable.'' An example of righteous propaganda.

As for the ABC Closeup ''Fortress Israel'' (ABC, Wednesday, 10-11 p.m.), it is difficult to imagine a study of the reasons for today's seeming Israeli obsession with security which does not somehow slight the Palestinian point of view. But this program succeeds in presenting a balanced and insightful interpretation of the elements in history which make for the fortress psychology of Israel.

''Fortress Israel,'' produced by Judy Crichton (under the aegis of Pamela Hill and Richard Richter), is reported with skillful sensitivity by Marshall Frady. One gets the sense of a people who have finally matched their religious identity, racial identity (Jews), or both, with a national identity clashing bitterly with a people (Palestinians) who are also simultaneously involved in discovering their own national identity. ''Fortress Israel,'' in digging deeply into the European background of the problem, has come up with an extraordinarily enlightening documentary, one that is not content to repeat charges and countercharges that only serve to exacerbate the issues, but instead delves into the overall reasons for contemporary attitudes. Neither the European Holocaust nor the hardships during the British rule of Palestine are overlooked. Thus, almost without regard for present-day troubles, it becomes clear why Israeli survivors are determined never to give up their security.

While extremists on both sides are included, the emphasis is on the moderates on both sides, none of whom are especially optimistic for a peaceful solution. However, the documentary allows you to experience your own revelations about the problem.

Extremists on both the Palestinian and Israeli sides will inevitably be furious with ''Fortress Israel'' -- but moderates on both sides will probably be pleased. As should anybody who really wants to understand not only what is happening in the Middle East, but why it is happening. One hopes that Miss Crichton's next project will be a similar study of the Palestinian psyche.

''Fortress Israel'' performs a much-needed public service in what appears to be a sincere search for enlightenment.