Time to Learn New Lines in Political Play : Reapportionment: New district lines have lawmakers assessing their gains--and losses--of territory.

Like many other Southern Californians, state Sen. David A. Roberti spent part of last weekend checking out San Gabriel Valley real estate.

But Roberti wasn’t trying to land a good deal on a fixer-upper. Instead, he was cruising the neighborhoods of Altadena and Pasadena to determine how they would fit with his Hollywood-based state Senate district.

When Roberti, president pro tem of the Senate, last week unveiled a plan to redraw the boundaries of the state’s 40 Senate districts, his own district had stretched eastward, in effect trading Dodger Stadium for the Rose Bowl. It would include about 75% of Pasadena and Altadena.

In a shotgun political marriage a decade ago, many of these heavily Democratic and predominantly black areas were attached to a San Joaquin Valley-based state Senate district currently represented by Sen. Don Rogers (R-Bakersfield).

The switch to Roberti, a Democrat, would give residents a representative much closer to home as well as a lawmaker who wields considerably more power than Rogers.

Pasadena Mayor Jess Hughston welcomed the possible change in representation, saying that tying Pasadena to Bakersfield “always dismayed me, and I’m glad that we can move most of our city into one district.” The rest of the city would continue to be represented by Sen. Newton R. Russell (R-Glendale).

Moreover, Hughston said, the change could help his city, where Democrats make up slightly more than half the registered voters. He added, “I’m encouraged . . . because with his (Roberti’s) clout, perhaps we can achieve more” in the way of state funds for local projects.

The new lines--which also would add part of Glendale to Roberti’s political turf--were released at a Capitol news conference by Roberti and Republican Senate Leader Ken Maddy of Fresno. Reapportionment, a once-a-decade exercise to ensure equal population in each district, is based on 1990 Census figures.

Whether the new state Senate political map will be adopted remains in doubt. The plan is still subject to fine-tuning before it is voted on by lawmakers, who are scheduled to redraw Assembly, Senate and congressional lines before their scheduled recess for the year on Friday. Maps for the Assembly and congressional districts are to be released later this week.

At stake in the plan is control of the 40-member state Senate, where the breakdown is 26 Democrats, 13 Republicans and 1 Independent.

Although there are changes in geography, party affiliation among registered voters in San Gabriel Valley districts remains almost unchanged, meaning the legislative seats are still relatively safe for one party or the other.

As expected, the Senate redistricting plan shifts political clout away from coastal areas and into inland counties that have been growing at a much faster clip. At least one new district is being created in the Inland Empire, whereas some existing districts have to drop constituents to meet population limits.

Sen. Ruben S. Ayala (D-Chino), for example, had to shed 163,000 people in the fast-growing San Bernardino area to drop down to the 744,000 people required in Senate districts. Ayala’s district would continue to cover Pomona.

Another significant change would occur in Monterey Park and Alhambra, two cities that would become part of a new district with a largely Latino population. The district would stretch from North Long Beach into the San Gabriel Valley and is currently represented by Sen. Ralph C. Dills (D-Gardena).

This change was triggered by the dictates of the federal Voting Rights Act, which directs map-makers to maximize the opportunities of blacks, Latinos and other minorities to win legislative seats.

A look at the San Gabriel Valley Senate districts as proposed by the Senate leadership shows:

* Rogers’ 16th District would be pushed out of Pasadena and Altadena, retain parts of the San Joaquin Valley and add San Luis Obispo County and Santa Maria on the Central Coast. The district’s Republican registration would jump 4% to 44.7%.

* Russell’s 21st District would keep Palmdale and Lancaster as well as parts of Glendale and Pasadena. It would also include Sierra Madre, San Marino and Temple City and part of Glendora. The district would stay solidly Republican with 55% GOP voter registration.

* Roberti’s 23rd District would continue to encompass Burbank, Griffith Park, West Hollywood and Hollywood as well as the Silver Lake and Hancock Park neighborhoods of Los Angeles. But the district would drop the southwest corner of Hancock Park, Dodger Stadium and Koreatown in Los Angeles. And it would pick up parts of Glendale, Pasadena and Altadena. Voter registration would remain solidly Democratic, but the margin would drop to 55.5% Democratic from 58.4%.

* Sen. Art Torres’ 24th District would continue to cover South Pasadena, downtown Los Angeles and Highland Park. It would drop Eagle Rock, Maywood, Bell Gardens and Commerce but add Echo Park and Koreatown in Los Angeles. The district would remain nearly 66% Democratic in registration. The Latino population would be 71%.

* Sen. Bill Leonard’s 25th District would drop 144,000 people in Inyo County and the desert portions of San Bernardino County to reach the 744,000 mark required in Senate districts. The district would include West Covina and part of Glendora as well as the western portion of San Bernardino County. The district would remain solidly Republican, with GOP voter registration around 51%.

* Sen. Charles M. Calderon’s 26th District would keep Pico Rivera, El Monte, Irwindale and La Puente, but drop Temple City, Rosemead, Alhambra, Monterey Park and Montebello. It would pick up Azusa, Norwalk, Santa Fe Springs, Artesia, the City of Industry, West Covina and parts of Whittier. Democratic voter registration would remain about 60%. The Latino population would be almost 62%.

* Dills’ 30th District would retain Paramount and Lynwood and add Alhambra, Cudahy, South Gate, Huntington Park, Maywood, Bell, Bell Gardens, Monterey Park, Commerce and Montebello. It would drop large sections of the South Bay. Democratic registration would be 62% compared to 66.4% in Dills’ current district.

* Sen. Frank Hill’s 31st District would keep Whittier, Brea, Diamond Bar, La Mirada, Hacienda Heights and parts of West Covina. It would drop southern Orange County but pick up Cerritos, Downey and parts of Lakewood and Bellflower in Los Angeles County, and Buena Park, La Habra, Cypress and Los Alamitos in Orange County. Republican voter registration would drop from 54.5% to 48.2%, though that is still considered a safe GOP seat.