MINNEAPOLIS (AP) — Bills to nullify Minnesota's water quality standard for wild rice, speed Enbridge Energy's proposal to replace its deteriorating Line 3 crude oil pipeline and block regulations meant to keep nitrates out of drinking water are advancing through the Minnesota Legislature, which reconvenes Monday after its Easter break.

Here's a look where some key environmental legislation stands at the midway point of the 2018 session:

WILD RICE

The long fight over a 1973 state law limiting discharges of sulfates into rice-producing waters to 10 milligrams per liter has heated up. Mining companies and wastewater treatment plant operators say the largely unenforced standard is unworkable and outdated. Environmental and tribal groups are fighting to preserve it, saying it's necessary to protect a food source that plays a crucial role in Ojibwe culture. They also say the bill would violate the federal Clean Water Act.

The 2011 Legislature directed the Minnesota Pollution Control Agency to update the standard. The agency has proposed replacing the 10 mg limit with a mathematical formula tailored to individual lakes and streams. But that approach foundered in January when an administrative law judge rejected the proposed change. The MPCA has made some modifications and asked the judge to reconsider.

Bills to simply nullify the current standard and force the MPCA to restart the full rulemaking process if it wants to proceed with a new standard have already passed five committees in the House and Senate. The bills will get additional committee hearings Monday and Tuesday.

NITRATES

Gov. Mark Dayton unveiled an updated draft proposal last month that aims at cutting nitrate levels in the state's water supplies by changing farming practices to reduce nitrogen fertilizer leaching into the groundwater and running off into streams.

Excessive nitrates can make water unsafe to drink, and the costs of removing them from public water systems and private wells can be prohibitive.

The Dayton administration's proposal would create voluntary and mandatory mitigation practices in vulnerable areas with porous soils, and in locations with high nitrate levels in public water supplies. It includes restrictions on the application of farm fertilizers in the fall.

That doesn't sit well with a lot of farmers and their allies who see the proposal as unnecessarily burdensome and expensive. They say farmers are already using less nitrogen than they once did. The main agriculture policy bills making their way through both chambers would block the rule from taking effect without approval from the Legislature.

LINE 3

The Public Utilities Commission plans to decide in June whether to approve Enbridge Energy's proposal to replace its nearly 50-year-old Line 3 crude oil pipeline from Canada with a new line across northern Minnesota, following a partly new route that would take it through the Mississippi River headwaters region, which includes lakes and streams where Ojibwe tribes harvest wild rice.

A bill to terminate the PUC's role and give Enbridge a green light has passed one House committee, though Dayton has threatened a veto.

Enbridge wants the replacement because Line 3 runs at only around half its original capacity. The Calgary, Alberta-based company says the old line is subject to cracking and corrosion and its maintenance needs are accelerating. It says the replacement would restore full capacity and ensure reliable deliveries to Midwestern refineries.

Critics, including the state Department of Commerce, say Minnesota doesn't need the project. Environmental and Native American groups say it would aggravate climate change and trample on tribal rights.

NUCLEAR POWER

A Senate committee has sent to the floor legislation that would give Xcel Energy an easier path for renovating its Monticello and Prairie Island nuclear power plants and keeping them operating until their federal licenses expire in the 2030s.

Xcel says the proposal would give it more certainty earlier in the process as it seeks to recover the costs, which are estimated at $1.4 billion over the next 17 years. The Minneapolis-based utility says keeping the plants running until their licenses expire will help it meet its goal of getting 85 percent of its power from carbon-free sources by 2030.

But critics say the bill essentially gives Xcel a blank check for shifting more of the expense and risk of cost overruns to consumers, bypassing the PUC's process for reviewing the costs and determining if they're prudent. Dayton has said he'll veto anything that undermines the PUC's authority.