Efforts to improve the health of DuPage County’s major streams are gaining steam, but there is still a lot of work to done, according to a report released this month by the local chapter of the Sierra Club.

The level of potentially harmful nutrients in the east and west branches of the DuPage River and Salt Creek are much higher than the statewide averages, according to the report titled “Restoring DuPage County Rivers.” But new legislation and greater efforts by local environmental groups and municipalities have the River Prairie Group — the local Sierra Club chapter — feeling positive about the future of the waterways.

“We’ve found that, unfortunately, pollution remains a problem,” said Jack Darin, director of the Illinois chapter of the Sierra Club. “But we’re confident that we’ve got a good chance to bring those pollution levels down because of the large number of people in DuPage County who have heard the cry to improve the streams.”

The group began testing the streams monthly in 2001, and since then the levels of phosphorus, nitrates and chloride in them have remained relatively high. Phosphate levels are more than four times the normal level for Illinois, and nitrate levels are also higher than average, according the report.

Phosphorus and nitrates are important to a healthy stream, but too much of the nutrients can cause algae and other aquatic plants to grow too quickly, choking out fish and other aquatic life. The main sources of these pollutants are sewage-treatment plants and runoff from fertilizers.

The main source of chloride pollution in the streams is salts used in the winter to de-ice roadways.

Since the group started collecting data on the streams, the Illinois General Assembly and the Illinois Environmental Protection Agency have passed some stricter water quality standards.

The DuPage County government also has taken a leadership role in improving the counties streams. The county’s Stormwater Management Department is working on a new law that would encourage builders to reduce the impact of new development on waterways.

The measure calls for newly constructed homes and additions to include “best management practices” — features such as rain gardens and permeable pavers — to offset added runoff caused by the project. If builders and homeowners choose not to use these methods, they could opt to pay a $2,000-per-acre fee to contribute to larger storm-water management efforts.

“What the ordinance hopes to get at by encouraging best management practices is reducing those pollutants getting into the streams after a rain event,” Anthony Charlton, director of the Stormwater Management Division, said in October.