MINNEAPOLIS -- The latest report card on Minnesota's waterways features a mix of positive signs and concerns about looming threats to the ecosystem.

The latest edition of the State of the River Report, produced by the National Park Service and Friends of the Mississippi River, finds pollution control efforts have restored wildlife habitat in many areas.

"The good news is that it once again is home to healthy bald eagle, mussel and fish populations, as pollution has been cleaned up and habitat has been restored our wildlife has locally really rebounded," Lark Weller of the NPS told reporters Wednesday.

"But the river is impaired by excess sediment, bacteria and phosphorous, which degrade aquatic habitat and recreation."

The authors consulted dozens of scientists to create the report and decide which key indicators to measure and compare with historic markers of river health. The overriding message is that progress is being made by vigilance and creative new solutions will be needed to fend off ongoing and growing problems.

"The river is a complex, living ecosystem and many factors affect its health," said Whitney Clark of the Friends of the Mississippi, as he explained why there's no simple answer for those who ask how the river is doing.

Clark is pleased with some of the policy changes that have occurred since the first State of the River Report was released in 2012. For instance Minnesota lawmakers banned the use of triclosan in hand soaps and other products because it was bonding with other chemicals in the environment to create a form dioxins.

The legislature also banned the use of coal tar pavement sealers that led to a buildup of polycyclic aromatic hydrocarbons or PAHs, in the environment.

And Congress voted to close the Upper Saint Anthony Falls Lock and Dam as a means of battling the spread of aquatic invasive species such as Asian carp.

One particularly worrisome trend is that river flows have increased in Minnesota, and the areas that have experienced the most significant changes in the landscape have seen the largest spikes in the volume of water moving downstream.

"Just like your pulse is symptomatic of what’s going on in your body, the flow in the river is symptomatic of what’s going on in the watershed," Shawn Schottler of the St. Croix Watershed Research Station and Science Museum of Minnesota remarked.

He said the Mississippi has seen a 25 percent increase in flow over the past 70 years, whereas the Minnesota River's flow has increased 50 percent. That increase flow makes it easier for the water to deliver sediment and pollutants downstream.

And while increased rainfall amounts has contributed to the higher flow levels, the majority of the changes are brought on by people altering the landscape.

"The things that change evaporation are like pavement – it doesn’t allow water to sit there and evaporate -- and changes in vegetation, and certainly in the agricultural world changes such as artificial drainage tiling," Schottler explained.

Levels of nitrates and sediments are still on the rise, especially in southern Minnesota where row crops are more common. Gov. Mark Dayton has focused on that issue, among others, in his clean water initiatives.

Pam Anderson of the Minnesota Pollution Control Agency, or MPCA, said that excess nitrates not only affect aquatic life in Minnesota with algae blooms, but also contribute heavily to the "dead zone" in the Gulf of Mexico where dying algae blooms have robbed the waters of oxygen.

"In Minnesota the biggest contributor is our agricultural regions," Anderson said. "It’s cropland drainage; it’s the groundwater associated with that and overland runoff."

But there are practical and financial limits to what can be done with privately owned land that borders the major rivers and tributaries.

"We’ve been nibbling around the edges with voluntary measures in the past, but clearly, as this report shows, it’s not getting us there," Clark said. "We’re really not moving the needle. So we need new policies that have potential to make big changes on the landscape."

River ecology experts have long encouraged city dwellers to plant rain gardens filled with deep rooted perennial plants that can hold onto water, slow runoff, encourage evaporation and naturally filter pollutants. That's also the thought behind restoring wetlands that were previously drained in order to make land productive for farming.

But the authors of the report would like the see that on a larger scale, by encouraging Minnesota farmers to plant perennials from time to time instead of concentrating solely on cash crops that are uprooted and replanted yearly.

"When those crops are not yet in the ground in the spring, or they're harvested early in the fall and are gone, we don't have plant material on that land to provide that evapotranspiration that stabilizes our hydrology," said Trevor Russell, the co-author of the report.

But he conceded that farmers, like everyone else, need to be paid for their work.

"It’s all well and good to say that we need more perennial crops in the landscape, but unless those things are profitable for producers that’s not going to happen. We don’t have the tools to compel that kind of widespread landscape change."

The report also urges homeowners and cities to use road salt and other deicing products more sparingly because it contributes to chloride pollution. And while chloride levels in most drinking water are currently at safe levels, it's not the kind of pollution that can be removed once it's in the water.

"Chloride is a permanent pollutant, so unlike some of our other pollutants it’s not going to break down or degrade over time," Brooke Asleson of the MPCA explained. "It’s going to continue to build up in our waters."

According to the report the Mississippi River still is below the recommended chloride limit, roughly one teaspoon per five gallons of water. But several of the Mississippi's tributaries in the Twin Cities metro area are above the limit or very near it.

Another growing threat comes from micro plastics, not just in the form of scrubbing beads but also from microscopic plastic fibers that are washed out of fabrics and some disposable paper products.

The report includes an accompany Policy Guide and a Stewardship Guide with suggestions about how individuals can make a difference.

There's also a Teacher's Guide for those who want to use the report as part of school curriculum.

Link to State of the River Report website: http://stateoftheriver.com