The algae bloom that temporarily turned the Ohio city of Toledo’s drinking water into toxic green sludge this month was an unsettling reminder that cleaning up the nation’s waterways remains a vital but unfinished job.

Thanks to the federal 1972 Clean Water Act, rivers no longer start on fire and the Great Lakes aren’t at the tipping point of becoming the North American version of the Dead Sea. But as the phosphorus-induced Lake Erie algae bloom revealed, pollutants are still making their way downstream, with serious consequences for public health and aquatic life.

That’s why a complex assignment recently completed by the Minnesota Pollution Control Agency (MPCA) merits public applause and support.

The state agency headed up the time-consuming task of determining an important new water quality standard for rivers and streams. Minnesota already has had phosphorus standards for lakes since 2008.

This summer, it adopted the new river standards for this common “nutrient,” which is found in human and animal waste. It’s a wonkish milestone but also a significant step forward when it comes to protecting Minnesota’s treasured waterways.

Water quality standards in general “establish pollution limits that protect our water resources for benefits like water recreation, fish consumption and healthy plant communities,” according to a Friends of the Mississippi River statement applauding the MPCA’s work. “If the water body fails to meet the standards, the state can require pollution reduction from those contributing to the problem and help restore the waters to health.”

The new standard’s value is heightened by the growing calls to shift many municipal drinking water sources from groundwater to surface water — a move that’s gained momentum as White Bear Lake’s shriveling has been linked to heavy aquifer use by surrounding municipalities.

Phosphorus is called a nutrient because it’s vital to plant growth, which is why it’s long been a fertilizer component. Unfortunately, algae thrive on it. So when excess amounts are washed downstream — usually as the result of human activity and development — algae blooms like the one choking Toledo’s drinking water intake can result.

According to the MPCA, high phosphorus levels are linked to agricultural runoff, wastewater treatment facilities, individual septic systems, urban construction and residential development. Managing and reducing phosphorus in waterways will require commitment from citizens, industry and local governments.

Strides already have been made in combating phosphorus in Minnesota, but the new standards provide a scientific foundation to strengthen and target water quality safeguards. Among the changes that may be needed: further reduction in phosphorus discharges from some sewage treatment plants.

Better management of agricultural runoff also needs to be weighed and spotlighted, particularly after an alarming Environmental Working Group report released this spring. The report from the nationally known advocacy group compiled aerial maps that showed that many streams running through southern Minnesota’s cropland are missing legally required buffer strips of natural vegetation. These small areas between fields and streams can help control runoff and prevent contaminants from reaching waterways.

Tougher enforcement of these laws and other changes to reduce phosphorus discharge, particularly at sewage treatment plants, are likely to generate controversy because of the cost and anti-regulatory rhetoric that has dominated public policy debates in some political circles.

No one enjoys red tape or paying more for basic services. But perspective is needed. These changes are manageable and far preferable to toxic green gunk contaminating rivers and lakes.

The MPCA’s new phosphorus standards build on good work done by the agency. Last year, its scientists released a gutsy report tracing nitrate water pollution back to the state’s politically powerful agriculture industry. Thanks to the agency, Minnesota is better prepared than many states to protect its water resources. The challenge now is to continue this valuable work and act on it.