MANKATO — The Minnesota River is straining from a big increase in water flow and the resulting sediment is offsetting slim gains in water quality.

Those are among the main findings of a study by the Minnesota Pollution Control Agency of the entire length of the river, from the western border to where it dumps its sediment into the Mississippi River.

The study, released Monday, found the amount of water flowing down the Minnesota River has doubled in the past 80 years. Some comes from more rain, but much of it comes from farm drainage systems. The loss of marshes and wetlands where water can be stored on the landscape has compounded the problem.

The MPCA says there are some signs of progress, and many farmers are exploring practices to reduce runoff.