Iowa has the attention of the nation’s agricultural sector because of a lawsuit filed in U.S. District Court by the water supply entity for the city of Des Moines — Des Moines Water Works — challenging drainage from field tile lines as discharges under the federal Clean Water Act that require a National Pollutant  Discharge Elimination System permit.

This suit is of interest to all of agriculture and the environmental community because no court has ruled as the DMWW is urging this court to do.

The lawsuit is a citizen suit under the CWA, because neither the federal Environmental Protection Agency nor the Iowa Department of Natural Resources is regulating the tile lines under the CWA. The DMWW believes both should be and therefore filed this suit as a citizen asking the court to require the EPA and DNR to regulate the tile lines by requiring an NPDES permit.

The suit was filed by DMWW on March 16, 2015, against 10 drainage districts in the northwest Iowa counties of Buena Vista, Sac and Calhoun. A two-week trial was scheduled for Aug. 8, 2016, but the judge recently rescheduled the trial to start June 26, 2017.

The petitioner, DMWW, is an independently owned and operated public utility. According to the DMWW’s website, it provides drinking water to approximately 500,000 people in the greater Des Moines area and is the largest water utility in Iowa and among the largest 100 utilities in the country. The DMWW is authorized under the Iowa Code, but it cannot levy taxes and is owned and funded by its customers. The DMWW is governed by a board of trustees that is appointed by the mayor of Des Moines.

The DMWW’s source for water is the Des Moines and Raccoon rivers. In addition to usual water treatment facilities, in 1992 the DMWW installed a nitrate removal facility and has operated the removal facility since then as required to meet federal drinking water standards (10 milligrams per liter for nitrates). In what has been a source of controversy, a small amount of the removed nitrates is stored, but the majority is returned to the river as part of a “brine” pursuant to the DMWW’s NPDES permit.

A risk to aquatic life

The DNR recently identified excessive levels of sulfate and chloride in the discharged brine and stated that this was a greater risk to aquatic life than nitrate levels. On Feb. 24, the DMWW announced that later this year it will route the brine through sanitary sewer treatment before it is discharged to the river. Even with that, 60% of nitrates will still be discharged to the river and sulfates and chlorides discharged to the river will be reduced and diluted, but not eliminated.

The defendant drainage districts are authorized by the Iowa Code to establish and maintain unified drainage systems to drain farmland. Many drainage districts were established in the early 1900s to construct and maintain adequate drainage outlets and levees in areas where adequate drainage could not be achieved by individual landowners.

As is the case for the defendants in this case, a county board of supervisors often serves as the board of trustees for that district. However, that does not mean that the counties themselves are defendants. A drainage district is authorized by Iowa law to assess fees to landowners within the district for construction and maintenance of joint drainage tile and ditches. According to the Iowa Drainage District Association, the state of Iowa maintains more than 3,000 drainage districts, and it is estimated that more than 9 million acres, or almost 26% of the state’s land mass, are drained.

DMWW also is making claims based on Iowa’s constitutional law that the nitrates in the water from the drainage districts amount to a taking without compensation, and violate constitutional due process and equal protection. Because these are state law issues, the federal judge referred these and other state law questions to the Iowa Supreme Court, and the parties have submitted briefs to the court for a decision.

Prior to starting this legal action, the DMWW conducted water sampling for nitrates at nine different locations within the defendant drainage districts in 2014 from March 18 until Dec. 30.

The legal argument

The critical issue in this lawsuit, as alleged by the DMWW, is whether discharges from field tile lines from the drainage districts are discharges from “point sources” without an NPDES permit under the CWA. Under the CWA, point sources are “discernable, confined and discrete conveyances.”

Up to this point, the EPA and DNR, and the courts, have considered outlets such as field tile lines to be nonpoint sources and not regulated under the CWA. The DMWW alleges that the drainage districts are different than a regular farm field and qualify as “point sources” due to the extensive, unified and engineered drainage systems within the districts.

Also at issue in the case are two CWA point source exemptions that arguably exempt the drainage districts from CWA NPDES requirements.

First is the ag storm water discharge exemption. DMWW alleges the drainage district tile lines do not qualify for this exemption because the tile drainage is artificially drained groundwater, not ag storm water runoff.

Second, is the exemption “return flows from irrigated agriculture.” The DMWW alleges this is not irrigated agriculture, but the drainage districts will argue that that term in the CWA is broader than the DMWW’s interpretation and applies to natural precipitation.

The DMWW also makes several claims under Iowa environmental law including that the discharges from the field tile lines are discharges from “point sources” without a permit. In addition, DMWW is claiming that the tile line discharges are a public, statutory and private nuisance and trespass, as well as negligence.

Rather than arguing over application of crop nutrients such as fertilizer or manure, the DMWW makes the basic argument that the prevalent corn-soybean crop rotation and lack of perennial crops in the districts, coupled with extensive subsurface tile drainage, results in excessive nitrates in groundwater that are discharged to surface waters. The DMWW alleges in its lawsuit that surface water runoff has fewer nitrates than tile discharges and that “the conveyance of nitrate is almost entirely by groundwater transport.”

Although this case is specific to the defendant 10 drainage districts in these three Iowa counties, the outcome of this lawsuit could eventually affect other drainage districts in Iowa, and drainage systems and farmland nationwide. If the court rules that drainage districts are point sources and do not qualify for the “ag stormwater” and “return flows from irrigated agriculture” exemptions in the CWA, then NPDES permits could be required for all drainage districts, a ruling that could then eventually be extended, either by the EPA or state regulation or further court decisions, to drainage tile outlets in individual farm fields.

It is this potential for legal and regulatory precedent beyond the 10 drainage districts that has drawn the attention of all of agriculture.

For those who want to stay up-to-date on the details of this case, Kristine Tidgren at the Iowa State University Center for Agricultural Law and Taxation, maintains an excellent webpage.