In hydrologic terms, a “gaining stream” is a surface stream augmented by groundwater flow. In a more conventional sense of the term, legal and policy disputes surrounding groundwater are also “gaining” in importance, though localized groundwater-related issues have perplexed the courts for generations. In a 1903 opinion, at the end of a lengthy discourse summarizing various authorities on the subject of groundwater withdrawals, Justice John B. Winslow of the Wisconsin Supreme Court admitted that “[p]erhaps more time has been spent in reviewing these decisions than is profitable, but the subject is interesting, and . . . should be given serious consideration.” Winslow’s comments came during the latter part of a long period of judicial unfamiliarity with the science of groundwater. Nineteenth century jurists characterized its movement and sometimes its very existence as “unknown” or even “occult.”
About two-thirds of Wisconsinites draw their drinking water from the ground. Still, both in this state and elsewhere, groundwater lacks the intuitive familiarity of surface water. Perhaps as a result, many states still don’t have well-developed jurisprudence or legal management systems for groundwater even though hydrogeology has become a well-developed and well-accepted science. Judicially-created groundwater doctrines vary widely from state to state. This legal dissonance is of increasing concern in light of a surge of groundwater problems and disputes involving water quality concerns, the viability of the public trust doctrine as a tool for groundwater regulation, and transboundary management issues, among many others. This societal and legal evolution proves Justice Winslow correct: The law of groundwater is indeed “interesting,” and courts are giving it ever more “serious consideration.” Consider the following examples:
Water quality issues. Several high-profile Wisconsin water issues are rooted in groundwater quality problems. Overpumping of deep groundwater aquifers was the first cause of the problems eventually resulting in the Waukesha diversion under the Great Lakes Compact. As the water table fell more and more, the city harvested water increasingly contaminated with radium, ultimately rendering it unsafe by EPA standards. And in Kewaunee County, the “karst” geology (shallow, cracked bedrock) allowed interactions between shallow groundwater and pollutants spread on the surface, causing widespread contamination of drinking water wells.
Most recently, news reports have documented the spread through groundwater of perfluorinated compounds likely originating from a northeastern Wisconsin manufacturer of specialized firefighting foams. This is important because the Ninth Circuit recently held that discharging pollutants into groundwater may require a Clean Water Act permit when the groundwater is hydrologically connected to a “navigable water” on the surface, as that term has been interpreted under the Act, even if the pollutants aren’t directly discharged into the surface water. So long as contamination entering surface navigable waters is “fairly traceable” to the point source, it doesn’t matter that it reaches that destination through a groundwater conduit. In fact, groundwater and surface water are almost always interconnected; indeed, groundwater is a major source of the flow volume of many rivers, lakes, and streams.
After the Ninth Circuit rejected a petition for en banc review, the losing party announced its intent to seek certiorari review, arguing that “the Court of Appeals’ decision conflicts with the CWA’s text, structure, and legislative history.” A D.C. Circuit decision handed down earlier this month allows EPA to avoid the nationwide application of certain federal court decisions, other than those of the U.S. Supreme Court or the D.C. Circuit, but there is little doubt that a similar issue will arise elsewhere; indeed, according to a motion recently filed with the Supreme Court, the same issue is currently the subject of five appeals in three other circuits. The cert petition in the Ninth Circuit case is due on August 27, 2018.
Ongoing saga of the public trust doctrine. I have previously written here about the public trust doctrine and its recent curtailment in Wisconsin. Much of that debate arose from disputes over how the Wisconsin Department of Natural Resources regulates groundwater withdrawals through high capacity wells. Specifically, the question is whether DNR may impose conditions on well owners and operators that limit pumping or require groundwater monitoring. In 2011, the Wisconsin Supreme Court held that the public trust doctrine authorizes DNR to impose such conditions. But in 2016 , Wisconsin Attorney General Brad Schimel wrote in a formal opinion that the case “is no longer controlling” based in large part on a newly enacted statute, Wis. Stat. § 227.10(2m) providing that WDNR must have “explicit authority” granted by a statute or rule to impose a permit condition; the public trust doctrine doesn’t qualify. Litigation over the issue is far from over. In Clean Wisconsin, Inc. v. DNR, a Wisconsin circuit judge held that the authority to impose such conditions resided in DNR’s general authority under Wis. Stat. § 283.001 to exercise “all authority necessary” to administer the permit system, and its authority under Wis. Stat. § 283.31 to “assure compliance” with effluent limits and standards. The case is now in briefing before the court of appeals. Another circuit court had previously held in 2015 that no statute or rule authorized imposing such conditions on a high capacity well authorization, and therefore DNR acted outside its authority by imposing them. Still another case pending in the court of appeals questions DNR’s failure to assert the public trust doctrine as a factor in considering high capacity well applications. The Wisconsin Supreme Court will likely have to revisit the issue soon.
Interstate disputes. In one high-profile case pending in the United States Supreme Court, the state of Mississippi claims that Memphis, Tennessee is pumping groundwater so heavily that a depression in the water table has formed and is altering the regional flow of groundwater. Mississippi claims “ownership” of the groundwater and has requested $615 million in compensation from Tennessee. For its part, Tennessee seeks apportionment and equitable sharing of the water. Water sharing disputes are likely to become more common with increasing water scarcity, and I can’t identify an interstate groundwater basin that is managed according to an enforceable legal agreement between states.
Wisconsin has long been a leader on the science of groundwater; it is one of only a few states that supports a special council, the Groundwater Coordinating Council, to facilitate the exchange of information about the resource among state agencies. Perhaps the Council will serve as a resource in some of the legal disputes described above. All in all, Justice Winslow would no doubt be gratified to know that his broad assessment of the subject matter still rings true. It deserves our serious attention.
 Huber v. Merkel, 94 N.W. 354, 117 Wis. 355, 359 (1903). Winslow became the court’s Chief Justice in 1907.
 Acton v. Blundell, 152 Eng. Rep. 1223, 1234 (Exch. Chamber 1843).
 Frazier v. Brown, 12 Ohio St. 294, 311 (1861).
 New Chester Dairy LLC v. DNR, No. 14-CV-1055 (Wis. Cir. Ct. Outagamie Cty., Dec. 2, 2015).