The word "infrastructure" has generally been a synonym for roads, bridges and transit at the State Capitol. That changed last week as Gov. Mark Dayton unveiled his capital investment proposal for the 2016 Legislature. This year and, it appears, for the next few decades, infrastructure improvement is also going to mean water projects — and they are going to be expensive.

Dayton's desire to preserve the quality of Minnesota's signature natural resource is one of several reasons that his bonding-bill proposal blows past the Legislature's outdated, arbitrary $1 billion ceiling for state bond authorizations per biennium. The proposal he unveiled Friday calls for a $1.4 billion bonding bill this year. It includes $220 million for water treatment and cleanup projects — a sum several times larger than any previous governor has proposed.

The DFL governor's total general obligation bonding package also would be a record-setter for a single year — if one ignores inflation. As management and budget Commissioner Myron Frans noted, then-Gov. Arne Carlson first proposed a $1 billion bonding bill in 1998. That was 10 percent of the state's yearly general fund budget then. Today, a 10 percent share would be $2 billion.

Those figures speak to a larger reality: For several decades, state spending on public facilities has not kept pace with needed upkeep, let alone allowed for investments that might better serve an evolving economy. Repairs on higher education campuses and at state correctional institutions repeatedly have been delayed. Heavily traveled bridges in Minneapolis and St. Paul have been neglected. Visitor spaces at Fort Snelling and Itasca State Park — much-visited places that ought to reflect Minnesotans' pride in their state — have become timeworn. Railroad safety upgrades have gone begging.

Dayton's proposal addresses those backlogs. If anything, his bids of $153 million apiece for the state's two higher education systems are sparing; each system is seeking tens of millions more. The governor is renewing a motion for a $70 million renovation at the Minnesota Security Hospital in St. Peter that he has made consistently since becoming governor in 2011. Improvements for the Minnesota Sex Offender Program take another $27 million and have a federal court order underscoring their urgency.

The inclusion of rebuilding money for both the Kellogg Avenue/3rd Street bridge in St. Paul and the 10th Avenue bridge in Minneapolis is welcome. But no transit projects and only rail safety and a few smaller transportation projects made Dayton's cut. He said he expects the Southwest light-rail line, which is at a make-or-break point for state funding, and other transportation needs to be met in a separate transportation bill. That means those projects remain in a political danger zone. Bills increasing transportation funding are notoriously difficult for the Legislature to enact; only one has become law since 1988.

The same fate should not befall the water infrastructure needs that Dayton highlighted. Aging facilities are taking a toll on water quality in many communities, leaving them unable to meet state and federal standards. A Minnesota Pollution Control Agency review tallied the need for 1,350 wastewater projects with a $4.2 billion price tag. The federal Environmental Protection Agency has estimated that Minnesota will need to spend $11 billion over the next 20 years to upgrade its water systems.

Those daunting sums can be made manageable only with a coordinated state-and-local policy that's sustained over a number of years. Dayton's proposal ought to be met at the Legislature with a sober awareness that maintaining drinkable and swimmable water is not optional for government in the "land of sky-blue waters." Understanding that aim as a responsibility shared by state and local governments is in keeping with Minnesota's tradition of valuing the quality of life and economic opportunity throughout the state. It's another illustration of what this page argued last month — that Minnesota is "better together," acting through robust state government to leave no region behind.