Law, Land Use, and Groundwater Recharge.

• Author: Owen, Dave

Table of Contents Introduction I. Groundwater Recharge and the Water Cycle A. Natural Water Cycles B. Human Influences C. Regulatory Challenges II. The Past and Present Law of Groundwater Recharge A. Developing Land 1. The common enemy 2. Urbanization 3. Stream and wetland fills B. Managing Floods C. Forests and Fields 1. Water and the woods 2. Agriculture, irrigated and otherwise D. Managed Aquifer Recharge III. The Future of Groundwater-Recharge Law A. The Circumstances for Groundwater-Recharge Law B. A Groundwater-Recharge Ethic C. The Instruments of Groundwater-Recharge Law Conclusion Introduction

Every day, around the world, billions of people rely on water pumped from wells. (1) They do so because groundwater is an extraordinarily useful resource. It is available over broad areas; even in landscapes where surface-water streams are few and far between, many people can access groundwater simply by drilling a well. (2) Because some contaminants filter out as water moves through the subsurface, groundwater is often cleaner than surface water. (3) And because groundwater usually flows slowly and evaporates only minimally, (4) groundwater storage can often last much longer than surface-water storage; groundwater therefore can remain available even during extended droughts. These benefits extend to ecological systems as well as human extractive users. (5) Because groundwater tends to be cleaner, cooler, and more steadily available than surface runoff, it plays a crucial role in sustaining many rivers, streams, wetlands, and lakes. (6)

Despite its value, groundwater is often ignored, misunderstood, or taken for granted, and inattention often goes hand in hand with unsustainable exploitation. (7) Consequently, groundwater supplies in the United States and around the world are being depleted, in some places with alarming speed. (8) That depletion is already leading to shortages, which are likely to spread and intensify as a growing global population uses more water and as climate change accelerates water stress. (9) The human costs of these crises can be immense. (10) So, too, are the environmental consequences; many surface waterways would not flow, and some have already ceased flowing, without inflows from groundwater. (11)

Yet even as groundwater resources come under growing strain, many people are eyeing groundwater as an increasingly important source of future supply. (12) Their reasons are straightforward: We must get water from somewhere, and in a warming world, with more droughts and less water precipitating as snow, less surface water will be available in many places, particularly during warmer and dryer seasons. (13) Water managers might compensate for increasingly erratic flows by building more dams and surface reservoirs, but in many areas, few good dam sites remain. (14) Dam construction and operation are also expensive and environmentally destructive, and much of the water stored behind dams evaporates before it can be used. (15) Turning to groundwater--which often can be stored for longer periods, with lower evaporation losses and with less environmental impact--seems like an appealing alternative. (16)

These water-supply crises and opportunities are intertwined with legal challenges. The challenges arise partly from the physical nature of groundwater. Because groundwater moves in response to pumping, wells in one area can drain water from beneath neighboring lands, (17) generating conflicts between neighbors. At broader scales, groundwater's tendency to flow across property lines makes it a common-pool resource and creates the potential for a classic tragedy of the commons. (18) Some combination of property rights and regulatory governance is a standard response to such potential tragedies, and consequently, groundwater extraction is governed by common law water rights, legislation, and administrative regulations. (19) These systems are often underdeveloped; (20) even in the United States, regulation of groundwater pumping has lagged behind regulation of surface-water use, and groundwater laws often provide spotty and ineffective coverage. (21) Nevertheless, for groundwater pumping, the overall trend is toward more pervasive and sophisticated regulation. (22)

As shown in the Figure above, however, pumping groundwater out of the ground is only one part of the groundwater cycle. Before groundwater is available to pump, it needs to get into the ground, which happens through a process known as groundwater recharge. (23) Groundwater recharge involves water infiltrating through the ground surface, percolating downward through unsaturated soil or rock, and then hitting the water table--that is, the level below which the pore spaces in subsurface soil or rock are filled with water rather than air. (24)

Despite its crucial role in water cycles, groundwater recharge has not received much legal attention. (25) There are obvious reasons why groundwater recharge is not a noticeable process; we usually do not see water's subterranean movements, and most people don't ponder where water goes when the ground surface dries up. (26) Additionally, recharge is a natural, gravity-driven process. In many places, water does not need legal assistance to move downward. Nevertheless, the locations and rates at which recharge occurs are heavily affected by pervasive human manipulation of the ground surface, and those human manipulations in turn are partially determined by law.

Human impacts on groundwater recharge take a variety of forms. Over much of the earth's land surface, humans determine what vegetation grows, and increasing the amount of water consumed by plants typically means reducing infiltration deeper into the ground. (27) People also decide where roads, buildings, and other impervious surfaces are constructed, and impervious surfaces control whether precipitation flows over or through the ground surface. (28) We move massive quantities of irrigation water, and some excess irrigation water becomes recharge. (29) Our often-antiquated systems for delivering water--for both agricultural and urban use--leak into the ground. (30) We constrain the movements of surface water, building levees that limit flooding and, therefore, limit the infiltration of surface water into areas adjacent to rivers and streams. (31) All of these manipulations of the land surface and the water cycle are at least partly the products of property rights, planning processes, permits, subsidies, and other regulatory decision-making, which means that groundwater recharge is partially determined by law. Yet law's effects on groundwater recharge have received little attention from policymakers and academic researchers.

This Article begins to fill that gap, addressing the United States' laws at the intersection of land use and groundwater recharge. It begins, in Part I, with a primer on how groundwater recharge works and how humans influence groundwater-recharge processes. Part I also explains why attention to groundwater recharge has become increasingly important and how climate change is likely to further increase that importance in years to come. Part II then turns to traditional legal doctrines governing the quantity of groundwater recharge. (32) It describes a hodgepodge of doctrines, many of which affect recharge without any underlying plan or design, and none of which seem matched for an era in which water managers increasingly call for carefully planned uses of groundwater.

Part III considers the future of groundwater-recharge law. More specifically, it turns to three basic questions that legal regimes for groundwater recharge must address. The first question is whether more robust regulation of groundwater recharge makes sense at all. In some places, the answer to that question will be yes, while in others, those systems would be more trouble than they are worth. Part III offers criteria for judging which is which. The second question is what sort of ethic should underpin a system of groundwater-recharge law. Any system of natural-resource regulation (or nonregulation) reflects judgments, often implicit, about our appropriate relationships with the natural world and with each other. Part III exposes the laissez-faire judgments inherent in existing law and explains how a more communitarian ethic would provide a foundation for better legal regimes. The third and final question is what regulatory instruments a more robust system of groundwater-recharge law should employ. There are many possibilities: Property-based regimes, informational regulation, planning, performance standards, prohibitions, and financial incentives all might have roles to play. But Part III suggests particular attention to mechanisms that use impact fees to encourage better groundwater management and to create pools of money to support selective governmental interventions.

In some ways, answering these questions requires delving into the unique science and policy of an often-ignored hydrologic process. But in other ways, groundwater-recharge regulation presents a microcosm of problems that recur all along the frontiers of environmental and natural-resource law. Groundwater-recharge law remains underdeveloped partly because of data gaps and limited understanding, and similar limits and gaps challenge many areas of environmental and natural-resource regulation. (33) Groundwater-recharge problems often arise from the cumulative effects of many individual landowners' actions, rather than from a few readily identified and easily targeted actors. (34) This, too, creates challenges that often arise both within and beyond the environmental field. (35) Finally, groundwater-recharge management can create difficult tradeoffs among different policy goals, and the challenge of managing difficult tradeoffs again helps define environmental and natural-resource law. (36) Although every regulatory challenge is unique in some ways, these commonalities mean that a study of...