WASHINGTON — Voter turnout in primaries has sunk to record lows in at least 10 states this year, making it ever more likely that political parties will fall under the control of an activist few, a report says.

One of the few bright spots is California, where an interesting race for governor and controversial ballot propositions caused a big jump in participation, the Committee for the Study of the American Electorate said in a study released Friday. The state also introduced an unusually open primary system this year.

Overall, primary turnout is on track to become the worst ever nationally, and the same could happen in the general election in November, the report said.

Curtis Gans, committee director and longtime student of voting trends, said Americans continue to show the political disengagement that has driven participation down nearly 25 percent in the last three decades. He said neither civic duty nor many of the modern voting conveniences will motivate many people to vote — only a high-stakes contest or national crisis seems capable of doing that.

“Primaries are and should be for the active and interested in each party,” he said. “But the level of party participation has fallen so low that we are at one and the same time threatening the cohesion of American politics and in danger of one or another party being captured by minority fringes.”

Turnout fell to 16.9 percent of eligible voters in this year’s early primaries, down almost three points or 14 percent from the 1994 midterm primaries. Average turnout in Democratic statewide primaries dropped to 9.5 percent, the lowest in history for the party, while average Republican turnout, traditionally lower, dropped slightly to 7.9 percent.

In the 16 states that held two-party statewide primaries by mid-June, turnout hit record lows in Alabama, Arkansas, Idaho, Maine, New Mexico, North Carolina, North Dakota, Oregon, Pennsylvania and Texas, Gans said. Texas posted the lowest turnout, at 7.6 percent.

Turnout rose in three states with two-party statewide primaries, reaching about 23 percent in California and 26 percent in both Kentucky and Nebraska.

It’s clear that “when there is something important to decide, citizens will come out and vote,” Gans said. “On the other hand, it is apparent that in the majority of elections, citizens increasingly see little of importance to decide, and are decreasingly motivated either by partisan interest or civic duty.”

Gans also found that steps to increase voter registration and make voting easier did not pay off in participation in the 1996 presidential election, underscoring his point that what ails the electoral system “is not procedural but motivational.”