CITY OF WATERBURY ET AL. v. TOWN OF WASHINGTON ET AL., 260 Conn. 506

Opinion BORDEN, J. The named plaintiff, the city of Waterbury (Waterbury), appeals and the named defendant, the town of Washington (Washington), cross appeals from the judgment of the trial court, rendered after a court trial, granting a permanent injunction in favor of the defendants and enjoining Waterbury’s current operation of its water distribution system. In its appeal, Waterbury claims that the trial court improperly concluded that:

(1) Waterbury violated the Connecticut Environmental Protection Act (CEPA), General Statutes § 22a-14 et seq.; (2) the relief granted under CEPA did not constitute a taking of Waterbury’s vested rights; and

(3) Waterbury failed to establish a prescriptive easement to use the waters of the Shepaug River and interfered with the riparian rights of the defendants. In its cross appeal, Washington claims that the remedy ordered by the trial court does not sufficiently cure Waterbury’s breach of a certain 1921 agreement between Waterbury and Washington.

We conclude that: (1) the trial court utilized an improper standard to determine whether Waterbury violated CEPA; (2) the trial court improperly concluded that Waterbury had not established a prescriptive easement against the riparian rights of the defendants; and (3) our conclusions regarding the CEPA and the riparian rights issues undermine the trial court’s ordered remedial release of water, including the remedy ordered on Waterbury’s breach of contract claim. Accordingly, we reverse the judgment of the trial court.

Waterbury brought this action, seeking a declaratory judgment that: (1) it has not breached a certain 1921 agreement between it and Washington; (2) it had not unreasonably polluted, impaired or destroyed the public trust, as provided in General Statutes § 22a-16; and (3) its conduct does not constitute a public or private nuisance, or a violation of any existing riparian rights.

The defendants counterclaimed that Waterbury had: (1) unreasonably polluted, impaired or destroyed the public trust in the water of the state in violation of § 22a-16; (2) engaged in conduct constituting both a public and private nuisance; see footnote 4 of this opinion; and constituting a violation of the defendants’ riparian rights; and (3) breached the 1921 agreement between Waterbury and Washington. After a court trial, the trial court rendered judgment for the defendants.

This case concerns the use of the Shepaug River as a source of Waterbury’s and various surrounding towns’ water supply, and the effect such use has on the water conditions in the Shepaug River.

As the trial court stated, this case pits those that view the Shepaug River as an “abundant and low cost supply of potable water” against those who wish to maintain “the natural condition of a beautiful and nearly pristine river . . . .” The trial court found the following facts, which are not in dispute. “Waterbury first developed in the low-lying portions of its present location and expanded up the sides of the surrounding hills. The growth of [Waterbury] in the last part of the nineteenth century and the first decades of the twentieth was related to the development of mills and manufacturing.

In 1893, the General Assembly authorized Waterbury to increase its water supply by taking water from ‘any and all brooks, rivers, ponds, lakes, and reservoirs within the limits of the county of New Haven or the county of Litchfield such supply of water as the necessities or convenience of the inhabitants of said city may require.’ [11 Spec. Acts 322, No. 252, § 1 (1893)]. Later enactments excepted Bantam Lake and certain waters of the Naugatuck River. [15 Spec. Acts 912, No. 344 (1909) and 17 Spec.

Acts 84, No. 101 (1919)]. “Rapid growth in population and some dry years in the first decade of the twentieth century strained [Waterbury’s] public water supply. The supply was insufficient at times to maintain pressure to the homes and buildings on the higher elevations, served by the ‘high service’ line. The Wigwam Reservoir, built in 1893, was supplemented by the Morris Reservoir, which was under construction from 1910-1913. By 1917, water for both the high service line and the low service line, which serves the downtown area, came directly from these two reservoirs.

The Morris and Wigwam reservoirs collect and store water from an eighteen square mile watershed basin known as the Branch Brook basin, through which the Wigwam Brook also runs. (This basin has been variously described during the trial as the ‘Wigwam basin’ or the ‘Branch Brook basin’ to distinguish it from the ‘Shepaug basin’ in the territory from which Waterbury’s water supply is derived.) “The higher in elevation of these two reservoirs is the Morris Reservoir.

When the Morris Reservoir is full, at an elevation of 515 feet, the water from that reservoir spills out and flows down to the Wigwam Reservoir, which reaches its overflow point at 424.8 feet of elevation.

When the Wigwam Reservoir is full, it spills into the Branch Brook, which eventually empties into the Naugatuck River. “In 1917, [Waterbury’s] engineers reported the need for additional water. [Waterbury] obtained land in the valley of the Shepaug River and built a seven and one-half mile long tunnel to deliver water diverted from that river to its water system in the Wigwam basin. “[Washington] was wary of [Waterbury’s] acquisition of water from the Shepaug River and introduced legislation in the General Assembly to repeal the 1893 [Special] Act.

It withdrew the bill upon executing a contract with [Waterbury] on May 3, 1921.

By the terms of that contract, [Waterbury] pledged not to reduce the stream flow in the Shepaug River below 1.5 million gallons per day between May 1 and November 1 of each year. [Waterbury] further agreed that ‘it will not divert water from the west branch of the Shepaug River at any time when the distributing reservoirs into which the [Waterbury] aqueduct shall convey such water so diverted are full and overflowing.’ The 1921 contract provided that [Waterbury] would divert such water only ‘to the extent that it may be required to supply the actual needs of the customers of said city and to maintain the storage in its potable water supply reservoir.’ “The Shepaug Reservoir, located behind the Shepaug Dam that was under construction from 1929 to 1933, is located about eight miles west of the reservoirs in the Wigwam basin.

The watershed basin for the Shepaug Reservoir is about twenty-eight square miles in size. In 1943, [Waterbury] completed the Pitch Reservoir, into which the flow from the Shepaug tunnel was directed.

The Morris Reservoir is immediately downstream from the Pitch, which, in addition to water received from the Shepaug basin through the tunnel, stores runoff from part of the Wigwam basin. “In 1963, to increase storage and supply, Waterbury built another dam and reservoir immediately to the north of the Shepaug Reservoir, known as the Cairns Reservoir, with a watershed of approximately ten additional square miles in the Shepaug basin.

The Wigwam basin’s watershed, at eighteen square miles, is roughly half the size of the Shepaug watershed, which occupies a total of thirty-eight square miles. . . . “There are, at present, three routes by which water leaves the Shepaug Reservoir: by diversion through the aqueduct tunnel to the Pitch Reservoir, by spillage down the spillway to the Shepaug River when the reservoir is full, and by release from a pipe in a chamber in the dam to the Shepaug River.

That pipe, which the witnesses referred to as ‘the eight inch pipe,’ if left full open releases a maximum flow of approximately 4.9 [mgd] down the Shepaug River. The flow may be considerably lower depending on the head of pressure. . . . “There is a pool at the foot of the Shepaug Dam. For a substantial distance south of the dam, the land on both sides of the river is owned by Waterbury. Peter’s Weir (a small dam) is located a short distance downstream from the dam, and a stream flow gauge has existed in the past at this weir.

About three miles below the weir the west branch of the Shepaug River reaches a confluence with the Bantam River, which is located to the east. From the confluence onward, about 50 percent of the summer flow of the Shepaug River is contributed by the Bantam River as measured by Dr. Kenneth Wagner at stream gauges installed in the summer of 1999.

The Steep Rock Association, Inc., operates a land trust of about 220 acres located on the Shepaug River both north and south of the confluence with the Bantam River and also in an area on the river north of Washington Depot. “The town center of Washington Depot is south of the confluence. The river flows south from the Depot through about 260 riverside acres owned by the Roxbury Land Trust, Inc., along which hiking and other recreational activities are permitted.

The parties agree that the stretch of river claimed to be affected by Waterbury’s flow diversions is approximately twenty-seven miles in length. . . . “The method of operating [Waterbury’s] water system which gave rise to dissatisfaction, and then to the claims of Washington, Roxbury, and their cocounterclaimants in this suit, began soon after Waterbury built a water treatment plant in 1988 to achieve compliance with water quality standards imposed by the federal government. [Waterbury] located the treatment plant close to the Morris Reservoir, so that water from the Morris and the Pitch could flow to the plant by gravity, without the need for pumping.

Water from the Wigwam would have to be pumped uphill to the treatment plant, incurring energy costs. [Waterbury] therefore drew its water almost exclusively from the Pitch and the Morris, with the result that the Wigwam Reservoir filled and either spilled over or was lowered by the release of water from a pipe into the Branch Brook, from which water flowed to the Naugatuck River. “Another feature of operation from at least 1988 onward was the use of turbines to pump water to the high service areas of the water supply system. The turbines were powered by the flow from the Pitch Reservoir.

A high flow or ‘head’ is required to operate these turbines, and water was diverted from the Shepaug Reservoir through the tunnel in large part to keep the Pitch Reservoir high enough to have the requisite head to power the turbines.

If the flow from the Pitch was insufficient, [Waterbury] would have to incur the costs of electrical power to pump to the high service area. “Official records establish that [Waterbury] operates its water supply system in a manner that results in a much greater impact on natural resources than is actually necessary to meet the needs of Waterbury’s users of water. [Waterbuiy’s] average daily demand is, and has been since 1990 between 16 and 17 [mgd]. This figure includes water sold to the intervenor towns and some other municipal entities.

Daily records maintained by [Waterbury], exhibit 514, make it possible to determine how much of the water being sent to the water treatment plant for use in the system on a given day comes from diversion from the Shepaug basin and how much from the Wigwam basin, which has a watershed of approximately half the size of the Shepaug watershed (eighteen square miles vs. thirty-eight square miles).

The daily records for the summer months of 1996, the summer before this suit was commenced, show that [Waterbury] was taking between 13.8 and 14.2 [mgd] from the Shepaug on days when the demand, as measured by the amount of water sent to the water treatment plant preparatory to distribution to customers, was between 16 and 18 mgd. This over-reliance on Shepaug diversions occurred on fourteen days in June, 1996, seventeen days in July, 1996, and sixteen days in August, 1996. On some days, [Waterbury] drew 14.2 mgd from the Shepaug when the demand was less than 16 mgd.

On many days that summer, [Waterbuiy] was diverting from the Shepaug even though the Wigwam basin reservoirs were full and spilling. “Another record of use, exhibit 516, shows that in August, 1996, [Waterbuiy] used no water from the Wigwam Reservoir, an average of 15.1 mgd from the Pitch and an average of only 3.4 mgd from the Morris Reservoir, while exhibit 514 shows an average daily diversion of 14.4 mgd from the Shepaug River to the Pitch Reservoir. . . . “[Waterbuiy’s] records indicate that before 1997, [Waterbury] limited the release of water to the Shepaug River between May 1 and November 1 to 1.5 [mgd].” The trial court also found that “[e]xcept for the dam and reservoirs at the head of its west branch, the Shepaug River is unusually free from the effects of human habitation and development.

No highways run along it, and much of the land along its banks is owned by land trusts or public entities or, though privately owned, is wooded and protected by local zoning from development close to its banks. The river is accessible, however, from several public roads, and it is used for hiking, fishing, swimming, seasonal kayaking and canoeing, and scenic enjoyment, especially in the areas owned and reserved for public use by the Steep Rock Association, Inc., and the Roxbury Land Trust, Inc.

Use is not restricted to local residents; the court heard eloquent testimony concerning enjoyment derived from the unspoiled beauty of the river from a truck driver from Wolcott who canoes on the river. The roster of users compiled by the Steep Rock Association, Inc., reveals recreational use by people from many parts of Connecticut and other states, including Boy Scout and Girl Scout camping groups.

The river flows through the town of Washington Depot and is a source of water for extinguishing fires in that town and on property along its banks. “For several years residents of the towns along the river and members of the Steep Rock Association, Inc., the Roxbury Land Trust, Inc., and the Shepaug River Association, Inc., have suspected that the diversion of water by [Waterbury] was causing the river to have extremely low flows in summer months, diminishing its natural beauty, reducing it as a habitat for fish and river organisms, and limiting its value for fishing and other recreation.

They brought their concerns to the attention of the Connecticut department of environmental protection, which regulates various aspects of natural resources, and to the department of public health, which has jurisdiction over many issues concerning public water supplies. The state established a task force to study the issues concerning the Shepaug River, but the work of the task force did not lead to a resolution of the conflict between the municipalities.

Waterbury and three towns (Wolcott, Middlebury and Watertown) that obtain, or seek to obtain, water from the Waterbury water bureau, perceived the rising criticism as a threat, and both sides to the controversy filed suit in late July, 1997, each seeking injunctive and declaratory relief.” Both cases were transferred to the complex litigation docket, and eventually merged into a single case, in which Waterbury’s request to be designated the plaintiff was granted.

Waterbury sought a declar atory judgment that its operation of the Shepaug dam did not: (1) constitute a breach of its 1921 contract with Washington; (2) violate CEPA by impairing the public trust; (3) create a public or private nuisance; and (4) violate any riparian rights of the defendants.

The defendants’ five count counterclaim alleged that Waterbury’s excessive diversions of water from the Shepaug River: (1) violated CEPA by unreasonably polluting, impairing, or destroying the public trust in the water; (2) constituted a public nuisance; (3) constituted a private nuisance; (4) interfered with the riparian rights of the defendants; and (5) constituted a breach of the 1921 contract between Washington and Waterbury. After a court trial, the trial court found for the defendants on the CEPA, riparian rights and contract claims, and for Waterbury on the public and private nuisance claims.

The court then entered an elaborate order for injunctive relief. This appeal and cross appeal followed. Additional facts will be set forth as they pertain to the various claims. I THE CEPA CLAIM Waterbury claims that the trial court improperly concluded that it violated CEPA by its operation of the Shepaug dam.

Specifically, Waterbury asserts that the trial court: (1) lacked subject matter jurisdiction over the CEPA claim because the defendants had failed to exhaust their administrative remedies; (2) improperly declined to apply the minimum flow statute; General Statutes §§ 26-141a through 26-141c; when evaluating the CEPA claim; and (3) improperly concluded that Waterbury’s conduct had resulted in an unreasonable impairment of the public trust under CEPA.

We conclude that: (1) the defendants were not required to exhaust administrative remedies before bringing their CEPA claim in the trial court; (2) the trial court’s finding of an unreasonable impairment is not consistent with the statutory scheme that the legislature has established in the area of watercourse management; and (3) the minimum flow statute governs the substantive analysis of whether Waterbury’s conduct has resulted in the unreasonable impairment of the Shepaug River.

Waterbury sought this declaratory judgment that its operation of the Shepaug dam had “not unreasonably polluted, impaired or destroyed the public trust” in the water of the state under General Statutes § 22a-16 of CEPA. The defendants counterclaimed, asserting that Waterbury’s excessive diversion of water from the Shepaug River unreasonably impaired the public trust in the water, thereby violating CEPA.

Although the defendants did not claim that the existence of the dam itself constituted an unreasonable impairment, they took issue with the manner in which Waterbury operated its water supply system in the summer, specifically its diversion of water via the aqueduct tunnel into the Pitch Reservoir and its effect on the release of water to the Shepaug River.

To resolve the question of whether Waterbury’s diversion of water from the Shepaug River violated CEPA, the trial court was required to determine whether Waterbury’s diversion was of such magnitude that it constituted, not merely an impairment, but an unreasonable impairment of the public trust in the river as a natural resource in violation of § 22a-16.

The trial court concluded that Waterbuiy’s operation of the Shepaug dam constituted an impairment when “the summer flow of water in the river is reduced below its natural flow in the months of May through October.” The trial court next found that “the defendants [had] made a prima facie case of unreasonable impairment of the public trust in the natural resources at issue, a flowing river,” because the impairment was more than de minimis.

Waterbuiy offered several special defenses to Washington’s CEPA claim, which, it argued, prevented the trial court from ordering any injunctive or declaratory relief pursuant to § 22a-16. Among such defenses were the claims that:

(1) No. 252, § 1, of the 1893 Special Acts, which authorized Waterbury to “take and convey from any or all brooks, rivers, springs, ponds, lakes, and reservoirs within the limits of . . . the county of Litchfield, such supply of water as the necessities or convenience of the inhabitants of said city may require,” and No. 252, § 3, which authorized Waterbury “in general, to do any other acts necessary or convenient for accomplishing the purposes contemplated by this act,” vested certain rights in Waterbury to take water from the Shepaug River and that any retroactive application of CEPA would constitute a taking of those vested rights; and

(2) General Statutes § 22a-20 prevented the trial court from granting any relief because there were adequate administrative and regulatory procedures available to the defendants to protect their rights. In support of this second special defense, Waterbury argued that the minimum flow statute established standards for minimum stream flow in stocked streams, which included the Shepaug River. Therefore, Waterbury contended, as long as it maintained flow in the Shepaug River in accordance with the minimum flow standards set forth by the department, it was, as a matter of law, in compliance with CEPA.

Waterbury also argued that, if its diversion amounted to a violation of the minimum flow statute, the defendants could seek the relief afforded under § 26-141c, through the involvement of the department.

The trial court rejected these defenses and determined that Waterbury’s current use of the Shepaug River constituted an “unreasonable impairment of the public trust in the natural resource at issue, a flowing river.” On appeal, Waterbury reasserts the aforementioned defenses, challenges the trial court’s determination of “unreasonable impairment,” and, for the first time, challenges the jurisdiction of the trial court to adjudicate the CEPA claim. We address these claims separately.

A Exhaustion of Administrative Remedies We first address Waterbury’s contention that the trial court lacked subject matter jurisdiction over the CEPA claim because the defendants failed to exhaust their administrative remedies. Specifically, Waterbury argues that the question of how much water it is required to release down the Shepaug River is governed by the minimum flow statutes, §§ 26-141a through 26-141c, which charge the department with enforcement.

General Statutes § 26-141b requires the department to “promulgate regulations establishing instantaneous minimum flow standards and regulations for all stocked river and stream systems.”

Section 26-141c empowers the department to enforce these standards. Waterbury also argues that only the department has jurisdiction to determine whether the minimum flow statute applies to the Shepaug River, rendering the trial court’s consideration of the issue improper. The defendants argue that, because Waterbury was the party that sought a declaratory judgment that it had not violated CEPA, thereby inviting the trial court to decide the issue, Waterbury should now be estopped from asserting this claim on appeal.

The defendants also argue that it would be particularly inappropriate in this case to entertain Waterbury’s jurisdictional claim, where the trial court “[a]t closing argument . . . invited the parties to comment on whether it ha[d] jurisdiction to decide all issues in the case.” The only potential issues so identified for initial agency consideration were two pending water supply applications by Wolcott and Middlebury for water from the Waterbury public water supply.

For the reasons set out in the following discussion, we consider but reject Waterbury’s claim that the trial court lacked subject matter jurisdiction to adjudicate the CEPA claim. “We note at the onset that... a claim that this court lacks subject matter jurisdiction [may be raised] at any time. Subject matter jurisdiction involves the authority of the court to adjudicate the type of controversy presented by the action before it. . . .

The objection of want of [subject matter] jurisdiction may be made at any time . . . and the court or tribunal may act on its own motion, and should do so when the lack of jurisdiction is called to its attention. . . . The requirement of subject matter jurisdiction cannot be waived by any party and can be raised at any stage in the proceedings. ... If at any point, it becomes apparent to the court that such jurisdiction is lacking, the appeal must be dismissed.” (Internal quotation marks omitted.) Dowling v. Slotnik, 244 Conn. 781, 787-88, 712 A.2d 396, cert. denied sub nom. Slotnik v.

Considine, 525 U.S. 1017, 119 S. Ct. 542, 142 L. Ed. 2d 451 (1998). Although we previously have noted “that there are limits to the notion that subject matter jurisdictional defects may be raised at any time”; (internal quotation marks omitted) Gangemi v. Zoning Board of Appeals, 255 Conn. 143, 150, 763 A.2d 1011 (2001); see also Vogel v. Vogel, 178 Conn. 358, 362-63, 422 A.2d 271 (1979); those limits were invoked in cases involving collateral attacks on judgments that had been fully litigated, and which all parties had had the opportunity for appellate review.

Although there may be instances in which a party who has invoked the jurisdiction of the court will not be permitted to claim later that the same court lacked jurisdiction, this is not that case, especially where two of the cases that Waterbury relies on for this claim, namely, Fish Unlimited v. Northeast Utilities Service Co., 254 Conn. 1, 756 A.2d 262 (2000) (Fish I), and Fish Unlimited v. Northeast Utilities Service Co., 254 Conn. 21, 755 A.2d 860 (2000) (Fish II), were decided after the trial court rendered its decision.

Therefore, despite Waterbury’s invocation of the court’s jurisdiction, we are constrained to address its contention that the trial court lacked subject matter jurisdiction over the parties’ CEPA claim. On the merits of the jurisdictional issue, Waterbury argues that our holdings in Fish I, Fish II and Polymer Resources, Ltd. v. Keeney, 227 Conn. 545, 561, 630 A.2d 1304 (1993), required the defendants first to exhaust all administrative remedies before bringing this action.

Waterbury further asserts that the minimum flow statute applies to the Shepaug River, and therefore establishes the amount of water that Waterbury is required to release. Because the department is charged with enforcement of the minimum flow statute, Waterbury contends, the trial court had no jurisdiction over this claim. The defendants argue, to the contrary, that the minimum flow statute does not apply to the Shepaug River. Although Waterbury disagrees, it claims that even this fundamental question is one for the department, not the courts, to resolve.

We disagree with Waterbury’s claim, and conclude that CEPA, as particularly demonstrated by General Statutes § 22a-18, does not embody the exhaustion of administrative remedies doctrine. Therefore, the trial court did have subject matter jurisdiction to entertain the defendants’ CEPA claim. “The doctrine of exhaustion of administrative remedies is well established in the jurisprudence of administrative law. . . . The doctrine provides that no one is entitled to judicial relief for a supposed or threatened injury until the prescribed administrative remedy has been exhausted. . . . McKart v.

United States, 395 U.S. 185, 193, 89 S. Ct. 1657, 23 L. Ed. 2d 194 (1969). . . . Johnson v. Statewide Grievance Committee, 248 Conn. 87, 95, 726 A.2d 1154 (1999). Where a statutory requirement of exhaustion is not explicit, courts are guided by [legislative] intent in determining whether application of the doctrine would be consistent with the statutory scheme. . . . Id., 96; accord McCarthy v. Madigan, 503 U.S. 140, 144, 112 S. Ct. 1081, 117 L. Ed. 2d 291 (1992).

Consequently, [t]he requirement of exhaustion may arise from explicit statutory language or from an administrative scheme providing for agency relief. . . . Howell v. Immigration & Naturalization Service, 72 F.3d 288, 291 (2d Cir. 1995). . . . Johnson v. Statewide Grievance Committee, supra, 97.” (Internal quotation marks omitted.) Hartford v. Hartford Municipal Employees Assn., 259 Conn. 251, 281, 788 A.2d 60 (2002).

Thus, the exhaustion doctrine is based on a judicial determination of a legislative intent that in certain cases the courts do not have initial subject matter jurisdiction because the legislature has committed the initial resolution of the matters in question to an administrative agency. Therefore, this doctrine does not apply when the legislature determines, by appropriate legislation, that a court may exercise subject matter jurisdiction despite the fact that there also may be administrative procedures available that would, absent such legislation, normally deprive the court of jurisdiction.

The defendants argue that CEPA, particularly § 22a-18 (b), is such appropriate legislation. We agree. Whether the legislature intended that the exhaustion doctrine apply to CEPA presents a question of statutory

interpretation. “The process of statutory

interpretation involves a reasoned search for the intention of the legislature. Frillici v. Westport, 231 Conn. 418, 431, 650 A.2d 557 (1994). In other words, we seek to determine, in a reasoned manner, the meaning of the statutory language as applied to the facts of this case, including the question of whether the language actually does apply.

In seeking to determine that meaning, we look to the words of the statute itself, to the legislative history and circumstances surrounding its enactment, to the legislative policy it was designed to implement, and to its relationship to existing legislation and common law principles governing the same general subject matter.” (Internal quotation marks omitted.) Bender v. Bender, 258 Conn. 733, 741, 785 A.2d 197 (2001). We begin our analysis with the text of the statute.

Section 22a-18 (

b) provides in relevant part: “If administrative, licensing or other such proceedings are required or available to determine the legality of the defendant’s conduct, the court in its discretion may remand the parties to such proceedings. . . . [T]he court shall retain jurisdiction of the action pending completion of administrative action for the purpose of determining whether adequate consideration by the agency has been given . . . .” (Emphasis added.) The statutory language of § 22a-18 (

b) strongly suggests that CEPA does not embody the exhaustion doctrine. “We have consistently held that may is directory rather than mandatory. See, e.g., Seals v. Hickey, 186 Conn. 337, 345-47, 441 A.2d 604 (1982). The word may, unless the context in which it is employed requires otherwise, ordinarily does not connote a command. Rather, the word generally imports permissive conduct and the conferral of discretion. See id., 345; Ridgeway v. Ridgeway, 180 Conn. 533, 540, 429 A.2d 801 (1980); see also A. Dubreuil & Sons, Inc. v.

Lisbon, 215 Conn. 604, 611, 577 A.2d 709 (1990).” (Internal quotation marks omitted.) Office of Consumer Counsels. Dept. of Public Utility Control, 252 Conn. 115, 122, 742 A.2d 1257 (2000). The legislature’s use of the word “shall” elsewhere in § 22a-18 (b), and the use of both terms throughout CEPA, further support our

interpretation. “The use of the word shall in conjunction with the word may confirms that the legislature acted with complete awareness of their different meanings; Hartford Principals’ & Supervisors’ Assn. v. Shedd, 202 Conn. 492, 506, 522 A.2d 264 (1987); and that it intended the terms to have different meanings. Hinchliffe v. American Motors Corp., 184 Conn. 607, 613, 440 A.2d 810 (1981) (use of different terms within same sentence of statute plainly implies different meanings intended), aff'd, 192 Conn. 252, 470 A.2d 1216 (1984); see also Plourde v.

Liburdi, 207 Conn. 412, 416, 540 A.2d 1054 (1988).” (Internal quotation marks omitted.) Office of Consumer Counsel v. Dept. of Public Utility Control, supra, 122. Thus, the plain language of § 22a-18 gives the trial court discretion on whether to remand an action to an administrative agency that has within its jurisdiction, appropriate “administrative, licensing or other such proceedings . . . .” General Statutes § 22a-18 (b).

Furthermore, as the defendants suggest, to conclude, as Waterbury urges, that the defendants must first turn to the department for a determination of whether the minimum flow statute applies, would render § 22a-18 a nullity. If a party were required to exhaust all administrative remedies before resorting to an independent action under CEPA, § 22a-18 (

b) could never be invoked, because a trial court would never have had jurisdiction in the first place so as to be able to “remand the parties to [administrative, licensing or other] such proceedings.” General Statutes § 22a-18 (b). We ordinarily do not read statutes so as to render parts of them superfluous; Giaimo v. New Haven, 257 Conn. 481, 493-94, 778 A.2d 33 (2001); and we see no compelling reason to do so with respect to § 22a-18. An examination of the legislative history surrounding the enactment of CEPA further reinforces our conclusion that § 22a-18 was meant to trump the exhaustion doctrine.

One of the overriding objectives of CEPA is to “enable persons to seek redress in the court when someone is [polluting] our environment.” Conn. Joint Standing Committee Hearings, Environment, Pt. 1, 1971 Sess., p. 163, remarks of James Wade, counsel for the majority leadership in the House of Representatives.

The bill was intended to “[expand] the right of a person to have access to the courts when property which we might say belongs to all of the public is jeopardized by the alleged polluting activity. [Prior to the enactment of CEPA] a person, unless he [could] show a personal direct ownership or other interests in the land which he claim[ed] as being affected by the alleged activity [did] not have legal standing in the court of law.

Consequently, some of the most beautiful aspects of our environment ... do not lend themselves to a proprietary or a personal interest and [CEPA] makes the guar anteeing and the preservation and the protection of these rights [previously unavailable] available to the general public . . . .” 14 H.R. Proc., Pt. 2, 1971 Sess., p. 739, remarks of Representative John F. Papandrea. Moreover, in enacting CEPA, the legislature realized that it was “granting individual citizens some powerful weapons, the right to seek injunctions, the right to intervene in proceedings.” 14 S.

Proc., Pt. 3, 1971 Sess., p. 1083, remarks of Senator Thomas F. Dowd, Jr. Although there was widespread support for permitting citizen suits concerning the environment, there was considerable debate over whether citizens must first exhaust all administrative remedies before being able to bring a separate action. When the environment committee held hearings on House Bill No. 5037, which, after several modifications, was passed as CEPA, the language of § 5 (1) through (4) was identical to what is now § 22a-18 (

a) through (d). This concerned a number of groups who testified before the committee, and who therefore urged the legislature to modify the bill and require a citizen to turn first to the appropriate administrative agency for relief before bringing suit in the Superior Court. Dale Van Winkle, of United Aircraft Corporation, testified that “we’re not opposed to a citizen-enforcement; however, we would like to see this done in the way that it’s done in other areas of law, and that is that the administrative agencies are exhausted first.

In most instances, you’re not allowed to bring suit unless you have exhausted your administrative remedies]. . . . What I would prefer to have you do is to give the remedy only after the individual has gone to the Water Resources Commission or the Clean Air Commission .... [I]f they get no action out of the Commission, then let them bring their suit.” Conn. Joint Standing Committee Hearings, supra, p. 177.

This concern was reiterated by Henry Darius, on behalf of the Connecticut Light and Power Company and the Hartford Electric Light Company, who stated: “Our concern is that the administrative process be allowed to run its course. . . . We are inclined to believe that a better way to solve the problems that these bills seek to solve is to give whatever additional direction and powers to the agencies. . . . We further would agree with the comments made by Mr. Van Winkle about the exhaustion of administrative] remedies.

We feel that where an administrative agency has jurisdiction over a problem, that agency’s powers should be allowed to be exercised without court interference, until such time as the agency’s actions have been completed. Then they are properly reviewable by the courts.” Id., pp. 204-205. It was not solely business interests that urged the legislature to apply the exhaustion doctrine to CEPA claims. David B. Beizer, the executive director of Connecticut Action Now, stated that “the only good criticism that’s been made of these bills, is that we should rely to the extent we can on the administrative process.

I wholeheartedly agree, and I think with a minor change in wording, this criticism can be taken care of. In other words, where there is an administrative agency . . . that agency should be consulted first, and administrative action should be sought first, prior to the citizen going to court.” Id., p. 216. Despite these suggestions, when the House debated Substitute House Bill No. 5037, § 5 (

b) still contained the permissive language: “If administrative, licensing or other such proceedings are required or available to determine the legality of the defendant’s conduct, the court in its discretion may remand the parties to such proceedings.” (Emphasis added.) It is clear from the debate on the bill that members of the House did not want to require citizens to exhaust their administrative remedies first.

As Representative Papandrea made clear-, “where administrative procedures are available the court, in its discretion can refer the case to the appropriate administrative agency for action, but once it does so, it will continue to retain jurisdiction over the case. So that if it is simply put to one side and forgotten, or not given the attention that it properly deserves, the plaintiff without incurring additional costs simply must bring this matter to the attention of the court and the court can then prod the agency and impose whatever orders it deems necessary to get the matter rolling.” 14 H.R.

Proc., supra, pp. 742-43. Many representatives felt that the agencies were not policing the environment as aggressively as they should. Representative Francis J. Collins stated: “[T]his is a necessary bill because it may well prod many of our state agencies charged with the protection of the environment . . . into more thorough and responsive carrying out of the legislative programs.” Id., p. 745.

They viewed this bill as intending to permit “an individual or a group to seek redress without waiting to go through the water resources commission or some other commission or board with its necessary delays and staggering along on the complaint.” Id., pp. 746-47, remarks of Representative Howard A. Newman. Although there was some support for the idea to attempt “to strengthen those environmental and ecology agencies that we have, give them the power to move in where there is a complaint and if they feel that the complaint is justified, let them take action”; id., p.764, remarks of Representative Robert D.

King; there was no attempt to amend the bill for that purpose. When the bill reached the Senate, however, Senator Dowd offered Senate Amendment

Schedule A, which would have substituted the word “shall” for “may” in what is now General Statutes §§ 22a-18 (

b) and 22a-20. See 14 S. Proc., supra, p. 1083. As Senator Dowd explained, “before we grant [citizens the right to seek injunctions and intervene in proceedings], which could result in dragging business into court with the exposure to costly time consuming litigations . . . [i]s it not reasonable to require the individuals to at least first exhaust the administrative procedures which we ourselves in this General Assembly have set up? ...

If, after exploring the administrative procedures he’s still unsatisfied, there’s nothing in this amendment to my mind, that would prevent his exercising his full rights which we will be granting under this bill.” Id. Several senators opposed the amendment, however, fearing that “if this amendment were passed, it would effectively emasculate this legislation. ... So often these matters do drag through administrative processes and no action was taken and the citizens [need] and [are] entitled in this bill, some direction. Direct action.” Id., p. 1084, remarks of Senator Roger W.

Eddy. “[0]ne of the problems that we’re having right now is, the fact that the administrative process [takes] so long that I certainly don’t want to give any grounds for them to be dumped back into that merry go round, that we have been having over the past four years.” Id., p. 1085, remarks of Senator George L. Gunther. “[M]y reading of it to changing of this one word, would change this statute from a statute whereby the public can sue to a statute whereby it would be in essence, simply a statute which grants an appeal, from the action of the administrative agencies.

This is certainly not the intent of the full statute.” Id., remarks of Senator James W. Macauley, Jr. This amendment was then defeated. Thus, given the plain language of § 22a-18 and the legislative histoiy of CEPA, the conclusion is inescapable that CEPA does not embody the exhaustion doctrine as a subject matter jurisdictional limit on the court’s entertainment of an action under it. The language is discretionary. The committee reported the bill out with that language unchanged. The legislative history evinces an intent not to incorporate the exhaustion doctrine.

A specific attempt in the Senate to amend it by inserting the exhaustion doctrine was defeated. Therefore, we conclude that, on the facts of this case, the defendants were not required to exhaust their administrative remedies, and that the trial court had subject matter jurisdiction over the defendants’ CEPA claims.

Despite the language of § 22a-18 and its accompanying legislative history, Waterbury, implicating the doctrine of stare decisis, contends that our prior case law requires the defendants to proceed first to the department for, at the very least, a determination of whether the minimum flow statute applies. “[T]he doctrine of stare decisis counsels that a court should not overrule its earlier decisions unless the most cogent reasons and inescapable logic require it.” (Internal quotation marks omitted.) Rivera v.

Commissioner of Correction, 254 Conn. 214, 251, 756 A.2d 1264 (2000). “In assessing the force of stare decisis, our case law has emphasized that we should be especially cautious about overturning a case that concerns statutory construction.” Conway v. Wilton, 238 Conn. 653, 681, 680 A.2d 242 (1996) (Peters, C. J., dissenting). Despite this reluctance, however, we have, on occasion, overruled cases that have involved the

interpretation of a statute. See, e.g., Ferrigno v. Cromwell Development Associates, 244 Conn. 189, 196, 708 A.2d 1371 (1998) (overruling prior inteipretation of General Statutes § 37-9 [3] because it created conflict between civil and criminal provisions of usury law); Santopietro v. New Haven, 239 Conn. 207, 215, 682 A.2d 106 (1996) (concluding that previous statutory analysis of General Statutes § 52-228b was flawed); Conway v. Wilton, supra, 681 (overruling prior

interpretation of General Statutes § 52-557f [3] as applied to municipalities). Thus the fact that there is preexisting case law on point is not, in and of itself, determinative of the issue presently before us. We acknowledge that Waterbury’s position is similar to that of the defendants in Middletown v. Hartford Electric Light Co., 192 Conn. 591, 473 A.2d 787 (1984), and Fish II, supra, 254 Conn. 21, two cases relied upon by Waterbury in advancing the argument that the proper forum for resolution of the CEPA issue was in the first instance, the department. In Middletown v.

Hartford Electric Light Co., supra, 597, and Fish II, supra, 31, we concluded that, pursuant to the doctrine of exhaustion of administrative remedies, the defendants were required to bring their claims to the administrative bodies entrusted with enforcement of the environmental statutes on which their claims were based. In neither of these cases, however, did the parties rely on or draw our attention to the language of § 22a-18 and its effect on our

interpretation of General Statutes §§ 22a-16 and 22a-19. The language of § 22a-18, coupled with the purpose of CEPA, compels us to overrule our prior cases concerning the exhaustion doctrine as applied to CEPA. Although this court has never directly addressed the relationship between the exhaustion doctrine and § 22a-18, we have addressed it in conjunction with §§ 22a-16 and 22a-19. These two sections provide citizens with several avenues with which to seek judicial redress.

Section 22a-16 governs independent court actions under CEPA, and § 22a-19 governs interventions into certain proceedings in order to assert CEPA environmental claims.

Pursuant to § 22a-16, the “Attorney General . . . any person, partnership, corporation, association, organization or other legal entity may maintain an action in the superior court . . . for declaratory and equitable relief against the state, any political subdivision thereof, any instrumentality or agency of the state or of a political subdivision thereof, any person, partnership, corporation, association, organization or other legal entity . . . for the protection of the public trust in the air, water and other natural resources of the state from unreasonable pollution, impairment or destruction . . . .”

Section 22a-19 (

a) permits these same parties, “[i]n any administrative, licensing or other proceeding, and in any judicial review thereof made available by law . . . [to] intervene as a party on the filing of a verified pleading asserting that the proceeding or action for judicial review involves conduct which has, or which is reasonably likely to have, the effect of unreasonably polluting, impairing or destroying the public trust in the air, water or other natural resources of the state.” We previously have addressed the reach of these two provisions in Connecticut Fund for the Environment, Inc. v.

Stamford, 192 Conn. 247, 470 A.2d 1214 (1984), and Middletown v. Hartford Electric Light Co., supra, 192 Conn. 591. In Connecticut Fund for the Environment, Inc. v. Stamford, supra, 248, one of the plaintiffs, the Better Neighborhood Association of Stamford (association), intervened in an administrative proceeding conducted by the Stamford inland wetland agency, denominated as the environmental protection board (board), pursuant to § 22a-19 (a), in which the board was reviewing an application for the development of a large tract of land to be used as apostal facility.

After the board approved the project, the association appealed on the ground that the board had excluded certain environmental evidence, even though the evidence was not related to inland wetlands, which was all that the board was charged with addressing. Id., 249-50. In affirming the dismissal of the association’s appeal, this court held: “Section 22a-19 is not intended to expand the jurisdictional authority of an administrative body whenever an intervenor raises environmental issues. Thus, an inland wetland agency is limited to considering only environmental matters which impact on inland wetlands.

Other environmental impacts must be raised before other appropriate administrative bodies, if any, or in their absence by the institution of an independent action pursuant to § 22a-16.” (Emphasis added.) Id., 250-51. We then addressed the reach of § 22a-16 in Middletown v. Hartford Electric Light Co., supra, 192 Conn. 591. In that case, the plaintiffs brought an action in the Superior Court to enjoin the defendants from burning PCB contaminated mineral oil at the defendants’ generating plant. Id., 592-93.

The trial court dismissed the four counts of the complaint that alleged that the defendants had failed to obtain various permits needed to dispose of PCBs, on the ground that the plaintiffs lacked standing. Id., 595.

On appeal, the plaintiffs contended that § 22a-16 gave them standing to bring an action to protect the environment from the damage that the PCB disposal could cause; id., 596-97; because § 22a-16 allowed “any person . . . [to] maintain an action in the superior court ... for the protection of the public trust in the air . . . from unreasonable pollution We affirmed the trial court’s dismissal of the plaintiffs’ action.

In applying our reasoning under § 22a-19, set out in Connecticut Fund for the Environment, Inc., we reaffirmed “that invocation of [CEPA] is not an open sesame for standing to raise environmental claims with regard to any and all environmental legislation. . . . These same principles [as enunciated in Connecticut Fund for the Environment, Inc.] apply to bar the city’s standing under the licensing statutes. The trial court was therefore correct in concluding that § 22a-16 did not provide the plaintiffs with standing under any statute other than [CEPA] itself.” (Citations omitted.) Middletown v.

Hartford Electric Light Co., supra, 192 Conn. 597. As a result of this decision, the plaintiffs in that case would be required to go to each administrative agency charged with issuing the necessary permits and seek redress there. In Polymer Resources, Ltd. v. Keeney, supra, 227 Conn. 545, we returned to the issue of standing, although not in the context of CEPA.

In Polymer Resources, Ltd., the commissioner of the department had issued an ex parte cease and desist order under General Statutes § 22a-7 against the plaintiff ordering it to cease various manufacturing processes until proper corrective action was taken. Id., 549. The plaintiff, although initially agreeing to be bound by the terms of the order, later sought an ex parte restraining order in the Superior Court against the department, preventing it from further interfering in the plaintiffs operation. Id., 555-57.

We held that the trial court did not have jurisdiction to enteitain the plaintiffs application for a temporary injunction against the department because the plaintiff had not first exhausted its administrative remedies by seeking “a declaratory ruling by the commissioner pursuant to General Statutes § 4-176 (a)” that portions of the department’s mandated remedies were improper. Id., 556. If the plaintiff were aggrieved by that decision, we noted, it could then appeal to the Superior Court pursuant to General Statutes § 4-183. Id., 558.

We stated: “It is a settled principle of administrative law that, if an adequate administrative remedy exists, it must be exhausted before the Superior Court will obtain jurisdiction to act in the matter. . . .

When a particular statute authorizes an administrative agency to act in a particular situation it necessarily confers upon such agency authority to determine whether the situation is such as to authorize the agency to act— that is, to determine the coverage of the statute—and this question need not, and in fact cannot, be initially decided by a court.” (Citations omitted; internal quotation marks omitted.) Id., 557-58.

We applied the reasoning of Polymer Resources, Ltd., to a claim brought under CEPA in Fish I, supra, 254 Conn. 7, where the plaintiffs, in addition to intervening in the defendants’ permit renewal proceedings before the department, brought an action in the Superior Court under § 22a-19. Although recognizing the exhaustion doctrine, the plaintiffs contended that “they [were] excused from compliance because the injunctive relief they [sought] was not available through the administrative process.” Id., 14.

Specifically, they argued that resorting “to the administrative remedies would have been futile and inadequate.” Id., 11. We rejected the plaintiffs’ contention that the available administrative remedies would have been futile or inadequate, and ordered the dismissal of the plaintiffs’ complaint on the ground that “the plaintiffs failed to exhaust their administrative remedies . . . .’’Id.

We reasoned that, because the permitting process was still in progress, “by failing to exhaust their administrative remedies, the plaintiffs . . . deprived the department of the opportunity to review a matter within its responsibility and expertise.” Id., 20-21. Argued at the same time was Fish II, supra, 254 Conn. 28, wherein we rejected the plaintiffs’ argument that, despite their failure to exhaust administrative remedies, they could maintain a separate action under § 22a-16.

Although we recognized that “§ 22a-16 abrogates the aggrievement requirement for bringing an action directly in the Superior Court, our case law explains the limitations of § 22a-16, and elaborates why the plaintiffs must pursue their claim by intervening in an administrative hearing before the department pursuant to § 22a-19.” Id., 31.

We declined to allow the plaintiffs to “use § 22a-16 as an ‘open sesame’ to litigate environmental issues that are governed by [General Statutes] § 22a-430, and which clearly have been placed within the exclusive domain of the department”; id., 34; and thus held that the plaintiffs lacked standing under § 22a-16 to bring their action. Id. Waterbury argues that the defendants’ entire complaint is premised on the lack of flow in the Shepaug River due to Waterbury’s diversion.

It contends that the rate of flow is governed by the minimum flow statute, which is enforced by the department, and therefore, like the plaintiffs in Middletown and Fish II, who were not allowed to bring independent actions under CEPA when an appropriate administrative body was available, so should the defendants in the present case be precluded from bringing this action, until the department addresses the minimum flow issue. As we have explained previously, a proper reading of § 22a-18 precludes the application of the exhaustion doctrine.

To continue to apply it to an action brought pursuant to § 22a-16 would be to defy both the language and purpose of § 22a-18. Moreover, in neither Middle-town, Fish I nor Fish II, were we apprised of the interplay among § 22a-18 and §§ 22a-16 and 22a-19. Now that this argument is before us, however, we cannot continue to apply the exhaustion doctrine to claims brought under CEPA. To the extent that this holding conflicts with our previous decisions applying the exhaustion doctrine to an independent action under § 22a-16, namely, Middletown, Fish I and Fish II, we overrule them.

Our rejection of the applicability of the exhaustion doctrine to CEPA actions brought pursuant to § 22a-16 does not mean, however, that a court having subject matter jurisdiction of such an action is therefore free to disregard any relevant and appropriate administrative scheme.

As we explain more fully in the discussion that follows, under the related doctrine of primary jurisdiction, which is embodied by § 22a-18 of CEPA, the court has discretion, and in certain cases should refer the case, or certain aspects of it, to the administrative agency, yet retain jurisdiction for further action, if appropriate, under that section. B The Minimum Flow Statute Having determined that the trial court had jurisdiction to entertain Waterbury’s declaratory judgment action and the defendants’ counterclaims concerning a potential violation of CEPA, we turn now to the merits of Waterbury’s appeal.

Waterbury claims that the trial court improperly concluded that the operation of the Shepaug dam resulted in an unreasonable impairment of flow in the Shepaug River under CEPA by: (1) applying an improper legal standard in determining whether there was an impairment; and (2) applying an incorrect legal standard in determining whether the impairment was unreasonable, by failing to evaluate the CEPA claim in terms of the minimum flow statute.

We conclude that: (1) the trial court applied the appropriate legal standard in its determination that the Shepaug River was impaired; and (2) it applied an improper legal standard in determining whether the impairment was unreasonable, because under the circumstances of this case, the Shepaug River is a watercourse that is subject to the minimum flow statute, and that statute gives substantive content to the determination of whether the impairment was unreasonable. Before addressing these issues, we briefly set forth the standard by which we review the trial court’s actions.

The meaning of the words impairment and unreasonable impairment, for purposes of CEPA, presents a question of statutoiy

interpretation, over which our review is plenary. State v. Ehlers, 252 Conn. 579, 589, 750 A.2d 1079 (2000). 1 Impairment The trial court, after noting that CEPA does not define the term “impairment,” observed that “the erection of a dam across a river alters that river.” The trial court concluded that, under CEPA, the Shepaug River was impaired during the months of May through October because the actual flow of water down the Shepaug River, as measured by one of Waterbury’s experts, was less than what the median natural flow of water would have been had the Shepaug dam never been built.

We agree with the trial court’s reasoning, and conclude that a dammed watercourse will be considered impaired, for purposes of CEPA, whenever the flow down that watercourse is less than what the natural flow would have been in the absence of the dam. First, the use of the word “impairment,” as applied in the context of a watercourse, suggests some diminution of the natural flow of the watercourse. Furthermore, that linguistic suggestion is consistent with the general legislative scheme of regulation of watercourses.

By enacting other statutes regulating the minimum flow of water in stocked watercourses and creating a permitting scheme for water diversions; see General Statutes §§ 26-141a through 26-141c; General Statutes § 22a-365 et seq.; the legislature has implicitly acknowledged that any diminution of natural flow has environmental consequences. The legislature chose, however, to tolerate a diminution in natural flow under certain conditions, as we discuss in

part I B 2 of this opinion. It is reasonable, therefore, to conclude that the meaning of the concept of impairment of a watercourse should be judged in relation to its natural flow rate. Additionally, as will become evident, this definition is consistent with this court’s

interpretation of the term “unreasonable impairment,” as used in CEPA. See General Statutes §§ 22a-15 through 22a-19. Thus, we conclude that the trial court properly determined that the construction of the dam impaired the Shepaug River, within the meaning of CEPA. 2 Unreasonable Impairment We next determine whether the impairment is unreasonable. The defendants argue that the trial court, relying on certain language in Manchester Environmental Coalition v.

Stockton, 184 Conn. 51, 57-60, 441 A.2d 68 (1981), properly concluded that any impairment that was more than de minimis, or not “so negligible that [it] would be asserted only for reasons of spite or for harassment,” constituted an unreasonable impairment.

The trial court then concluded: “The impairment of the river’s flow identified by the defendants is not so minor that invoking it can only proceed from spite or a desire to harass .... [T]he defendants have made a prima facie case of unreasonable impairment of the public trust in the natural resource at issue, a flowing river.” Waterbury argues that Manchester Environmental Coalition addressed only the issue of unreasonable pollution, not unreasonable impairment, and that our decision in Fish II requires us to make an unreasonableness inquiry with reference to the substantive law of the case, here, the minimum flow laws.

We agree with Waterbury, albeit for different reasons, and we conclude that the trial court’s

interpretation oí Manchester Environmental Coalition as standing for the proposition that the only meaning of the term “unreasonable impairment” is something more than de minimis was improper. On the facts of the present case, the term “unreasonable impairment” must be evaluated through the lens of the entire statutory scheme, if any, that the legislature has created to regulate the conduct underlying the impairment. What constitutes an unreasonable impairment for purposes of deciding whether a violation of CEPA has occurred in the Shepaug River is a question of statutory construction.

As previously stated, the term “impairment” is undefined in CEPA, as are the express eircumstances in which such impairment may be termed “unreasonable.” The other provisions of CEPA, however, aid in the ascertainment of the meaning of the term “unreasonable impairment.” General Statutes § 22a-17 sets the hurdles one must overcome in order to satisfy the burden of proof requirements set under CEPA. Pursuant to § 22a-17, “[although the ultimate burden of proof never shifts from the plaintiff, [CEPA] contemplates a shifting of the burden of production. See Ray v.

Mason County Drain Commissioner, 393 Mich. 294, 311, 224 N.W.2d 883 (1975). The plaintiff must first make a prima facie showing that the conduct of the defendant, acting alone, or in combination with others, has, or is reasonably likely unreasonably to pollute, impair, or destroy the public trust in the air, water or other natural resources of the state . . . .” (Emphasis added; internal quotation marks omitted.) Manchester Environmental Coalition v. Stockton, supra, 184 Conn. 57-58. “Once a prima facie case is shown, the burden of production shifts to the defendant.

Under § 22a-17, the defendant may rebut the prima facie showing by the submission of evidence to the contrary.” (Internal quotation marks omitted.) Id., 60. In addition to submitting contrary evidence, § 22a-17 (

a) permits a defendant to “prove, by way of an affirmative defense, that, considering all relevant surrounding circumstances and factors, there is no feasible and prudent alternative to the defendant’s conduct and that such conduct is consistent with the reasonable requirements of the public health, safety and welfare.” (Emphasis added.) For us to conclude, as the trial court did in this case, that unreasonable means only some level more than de minimis, the only evidence a defendant would be able to offer to rebut a prima facie case would be evidence that there was no pollution, impairment, or destruction of the natural resource.

Thus, in many circumstances, particularly when dealing with a dammed watercourse where some level of impairment is practically assured, the defendant’s only defense would be the separate affirmative defense that, “considering all relevant surrounding circumstances and factors, there is no feasible and prudent alternative to the defendant’s conduct and that such conduct is consistent with the reasonable requirements of the public health, safety and welfare.” General Statutes § 22a-17 (a).

An examination of the legislative history of CEPA, however, reveals that § 22a-17 was not meant to relegate a defendant to disproving a CEPA violation solely by resorting to this affirmative defense. Representative Papandrea, when explaining the burden shifting mechanism of CEPA, stated: “Once having brought the law suit, the plaintiff, the person who brings the law suit, [has] the burden of proving not just the fact that pollution has, or is about to occur. He must prove that the pollution complainfed] of is unreasonable and unavoidable. . . .

Since unreasonableness is a matter of fact to be determined by the judge after listening to both sides and all of the evidence which they have to present, there is no question that the judge will have access to all of the merits, to all of the implications, to all of the potential problems before he is called upon to make a decision.” 14 H.R. Proc., supra, pp.741-42.

This suggests that the legislature intended that a court would be called upon to consider much more than whether a party has brought a suit simply for purposes of spite or harassment or whether the conduct complained of was merely more than de minimis. If a court were, in fact, so limited in its determination of unreasonableness, the need for this level of evidentiary review would be obviated. The argument that unreasonable means anything more than de minimis is further undercut by the legislators’ belief that CEPA would not unduly interfere with business operations.

When some legislators expressed concern that CEPA could prevent a farmer from spraying his crop with pesticides, Representative John G. Matthews commented: “[T]he Bill in my estimation would not prohibit him from using a spray, he has the right to earn his living in his profession or occupation, and certainly unless he sprays indiscriminately all over and destroys things well beyond his own property line, there is certainly no restriction on it.” Id., p. 750.

This comment was echoed by Representative Papandrea whenhe stated: “[T]his [bill] does not in any way expand the present common law right of any individual in the state of Connecticut to bring a lawsuit in nuisance against anyone who is directly damaging him or his property by way of pollution. . . . [T]here is already in this state an action at law available to an abutting property owner.” Id., pp. 738-39. Moreover, some legislators expressed concern that CEPA could be used as a mechanism to drive away businesses.

In fact, at least in the eyes of one legislator, “[t]he Bill has been presented by the majority leadership as being so protective to the business community, to the farmer, as to make the Bill [innocuous]. The protective measures are such that we are lead to believe that technically no action would be taken under it. . . .

If it is not correct, and if there will be and can be under the Bill . . . harassment, suits, self seeking publicity suits, then the Bill is a bad one particularly bad at this time, where Connecticut is having financial and economic difficulties, it needs business, it needs jobs.” Id., p. 752, remarks of Representative Abijah U. Fox.

Yet, if any level of pollution, impairment, or destruction above what would be considered de minimis were sufficient to establish a prima facie violation of CEPA, then there would seem to be nothing to prevent such suits against groups such as farmers, where the neighboring land belongs to the public trust. It is clear that the legislature did not intend for a plaintiff to be able to establish a prima facie case under CEPA on the sole basis that the defendant’s conduct was causing something more than a de minimis impairment.

Despite this statutory text and legislative history, the defendants urge us to reaffirm our conclusion in Manchester Environmental Coalition v. Stockton, supra, 184 Conn. 58, that the “word ‘unreasonabl[e]’ [in the context of pollution] was added as a means of preventing lawsuits directed solely for harassment purposes.” In that case, we stated that “[t]he defendants argue that the word unreasonable was intended to permit the balancing of major state policies and competing interests. The clear legislative history shows that this was not the intent. . . .

The trial court found that the plaintiffs were not solely motivated by harassment purposes.” (Citation omitted; internal quotation marks omitted.) Id., 58-59 n.10. Therefore, we concluded, “the plaintiffs presented a prima facie case by showing a protectible natural resource (air) and that the action of the defendants would impair this resource.” Id., 58. We reached this conclusion based solely on the comments of Attorney Wade.

While discussing the differences between House Bill No. 5037, which included the word “unreasonably” and was enacted into law, and Senate Bill No. 400, which did not contain the word “unreasonably,” Wade stated: “Now in framing this legislation, it was our judgment that all of us pollute the environment to one degree or another, simply by breathing, obviously we introduce elements into the environment which are not natural.

And therefore, if we are going to permit the use of the courts by citizens to bring law suits against those who do pollute the environment, we believe there must be a check to prevent those suits which are brought simply for harassment, and for no other purpose.

Therefore, [House Bill No.] 5037, which Speaker [William R.] Ratchford has introduced, permits law suits against those who unreasonably pollute the environment. . . . [I]f [Senate Bill No.] 400 were passed with no check, then you might wind up with spite suits between neighbors and that sort of thing over conditions that are nothing more than spite between neighbors. We feel our bill, which imposes the reasonable standard, would be such as to eliminate that possibility.” Conn. Joint Standing Committee Hearings, supra, p. 162.

Although, taken in isolation, these comments may suggest that the term “unreasonable” meant only any impairment more than de minimis, Wade’s next comments contradict that meaning. Immediately after Wade made his comments explaining the insertion of the word “unreasonable” into House Bill No. 5037, he stated: “I recognize the fact that a person or company or corporation could be polluting the environment, andhispollu tion alone is not unreasonable.

But when his pollution is introduced into the environment in combination with others, it does become unreasonable, and the best example might be if someone is pouring filth or pollution into the Connecticut River. A large body of water, which standing alone would not be unreasonable, but when you combine it with everybody upstream, his little bit add[ed] thereto, makes it unreasonable.” (Emphasis added.) Id., pp. 162-63. If the term “unreasonable” meant only anything more than de minimis, the act of dumping any filth or pollution into a watercourse necessarily would be unreasonable.

It could not be contended that the suit was being brought solely for harassment purposes, and unless we were to subscribe to the notion that it would be permissible to dump pollution in small quantities and let the water dilute it, this polluting activity would likely cause more than a de minimis effect on the watercourse. Thus, if one can “pollut[e] the environment, and [that] pollution alone is not unreasonable”; id., p. 162; then the word “unreasonable” must have some meaning other than anything more than de minimis.

Even Manchester Environmental Coalition itself, despite its language to the contrary, envisioned a scheme in which a prima facie case consisted of more than the mere production of evidence illustrating something more than de minimis pollution, impairment or damage. In that case we stated: “Once a prima facie case is shown, the burden of production shifts to the defendant. Under § 22a-17, ‘the defendant may rebut the prima facie showing by the submission of evidence to the contrary.’ As stated in Ray v.

Mason County Drain Commissioner, supra, [393 Mich.] 311-12, ‘[t]he nature of the evidence necessary to rebut [the] plaintiffs showing will vaiy with the type of environmental pollution, impairment or destruction alleged and with the nature and amount of the evidence proffered by the plaintiff. In some cases, no doubt, testimony by expert witnesses may be sufficient to rebut [the] plaintiffs prima facie showing.

While in other actions the defendant may find it necessary to bring forward field studies, actual tests, and analyses which support his contention that the environment has not or will not be polluted, impaired or destroyed by his conduct. Such proofs become necessary when the impact upon the environment resulting from the defendants’ conduct cannot be ascertained with any degree of reasonable certainty absent empirical studies or tests.’ ” Manchester Environmental Coalition v. Stockton, supra, 184 Conn. 60.

If the only way to rebut a prima facie case were to offer evidence that the pollution, impairment or destruction, if it existed at all, was de minimis, then the quantity and quality of rebuttal evidence envisioned by this court in Manchester Environmental Coalition would be excessive and unnecessary. Rather, the previous quote, taken from Ray v. Mason County Drain Commissioner, supra, 294, envisions a scenario in which the rebutting party may offer evidence demonstrating that the degree of pollution, impairment or destruction does not rise to such a level as to require judicial intervention.

Therefore, to the extent that Manchester Environmental Coalition limits the meaning of the word “unreasonable,” in the context of an independent suit under CEPA, to anything that is more than de minimis, we are constrained to abandon that suggestion. Having determined that the term “unreasonable” as used in the context of an independent action under CEPA does not mean something more than de minimis, we next turn to the question of what it does mean, at least in the context of this case.

We conclude that when, as in the present case, as we discuss in more detail later in this opinion, the legislature has enacted an environmental legislative and regulatory scheme specifically designed to govern the particular conduct that is the target of the action, that scheme gives substantive content to the meaning of the word “unreasonable” as used in the context of an independent action under CEPA.

Put another way, when there is an environmental legislative and regulatory scheme in place that specifically governs the conduct that the plaintiff claims constitutes an unreasonable impairment under CEPA, whether the conduct is unreasonable under CEPA will depend on whether it complies with that scheme. We draw this conclusion from the overriding principle that statutes should be construed, where possible, so as to create a rational, coherent and consistent body of law. See, e.g., Doe v.

Doe, 244 Conn. 403, 428, 710 A.2d 1297 (1998) (“we read related statutes to form a consistent, rational whole, rather than to create irrational distinctions”); In re Valerie D., 223 Conn. 492, 524, 613 A.2d 748 (1992) (“ ‘[statutes are to be interpreted with regard to other relevant statutes because the legislature is presumed to have created a consistent body of law’ ”).

It would be inconsistent with that principle to conclude, absent some clear indication to the contrary, that the legislature intended that the same conduct that complies with an environmental legislative and regulatory scheme specifically designed to govern it, nonetheless could be deemed by a court to be an unreasonable impairment of the environment.

Put still another way, it would be anomalous to conclude that the legislature has, as a general matter, enacted an environmental regulatory scheme that runs on two different tracks with respect to the same conduct: one that requires compliance with specific criteria promulgated by a regulatoiy agency pursuant to a specific legislative enactment; and a second that lodges in a court the determination of whether the same conduct comes within the very general standard of reasonableness, irrespective of whether it is in compliance with those specific criteria.

Thus, in the present case, because we conclude, as the following discussion indicates, that, because the trial court found in effect that the Shepaug River is a stocked watercourse, and because both the defendants and the department have in this appeal assumed the propriety of that finding, the minimum flow statute and the regulations adopted pursuant to it apply to the Shepaug River. Therefore, the question of whether the impairment of the Shepaug River is unreasonable depends on whether its impaired flow meets the requirements of that statute and those regulations.

In this connection, we acknowledge that, as our previous discussion regarding the legislative rejection under CEPA of the exhaustion doctrine demonstrates, when CEPA was enacted there was significant legislative skepticism regarding the efficacy of the environmental regulatory agencies and, therefore, the legislature evinced an attitude favoring initial judicial, as opposed to initial regulatory, determinations of whether specific questioned conduct constituted unreasonable pollution, impairment or destruction of a natural resource.

Concurrent with and subsequent to that enactment, however, the legislature also has enacted numerous environmental regulatory programs, and it can hardly be said that our environmental regulatory agencies have lain dormant in implementing those programs.

In order to read our environmental protection statutes so as to form a consistent and coherent whole, we infer a legislative purpose that those other enactments are to be read together with CEPA, and that, when they apply to the conduct questioned in an independent action under CEPA, they give substantive content to the meaning of the word “unreasonable” in the context of such an independent action.

Furthennore, a contrary conclusion would also mean that, in defending against what a court deems to be a prima facie case of unreasonable conduct under CEPA, the only defense that could be offered would be the affirmative defense that there was no feasible and prudent alternative to the defendant’s conduct. As will be seen in our subsequent discussion of the minimum flow statute, however, in numerous areas the legislature has chosen to enact detailed regulatory schemes circumscribing a party’s conduct.

There is nothing in CEPA, or in its legislative history, to suggest that CEPA was intended to trump more specific statutes reflecting the legislature’s environmental policy in a specific area. It is reasonable to conclude, therefore, that when the legislature has enacted a specific statutory scheme concerning conduct that is later complained of, it also intended that a party be able to offer evidence of compliance with that statute which, if believed, would rebut a prima facie showing under CEPA.

Therefore, we do not interpret the term “unreasonable” in such a way as to relegate defendants in CEPA actions to the sole affirmative defense that there was no feasible and prudent alternative to their conduct. 3 The Minimum Flow Statute Having concluded that whether a watercourse has been unreasonably impaired may depend on a relevant regulatory scheme established by the legislature, we turn to Waterbury’s claim regarding the minimum flow statute. Waterbury claims that flow in the Shepaug River is regulated by the minimum flow statute.

Therefore, Waterbury asserts, as long as it was in compliance with that statute and its accompanying regulations, it could not be in violation of CEPA. The defendants argue that, assuming that the minimum flow statute applies to the Shepaug River, the trial court correctly concluded that the minimum flow statute was not intended to define “unreasonable impairment” of the river, because the minimum flow statute is concerned only with the protection of fish.

We agree with Waterbury, and conclude that the minimum flow statute is the standard by which the trial court must evaluate whether Waterbury has unreasonably impaired the Shepaug River. We first turn to the question of whether the minimum flow statute applies to the Shepaug River. “Because statutory

interpretation is a question of law, our review is de novo.” Andover Ltd. Partnership I v. Board of Tax Review, 232 Conn. 392, 396, 655 A.2d 759 (1995).

The trial court held, on Waterbury’s motion for reconsideration, that the minimum flow statute did not apply to releases from the Shepaug dam because the only indication of stocking was “evidence that relates to stream flow at a point in Roxbury, where the flow is a combination of the west branch of the Shepaug River and of the contribution of the Bantam River.” There was “no evidence of stocking of the stream primarily affected by [Waterbury’s] diversion of water, that is, the river between the dam and the confluence of the Bantam River.” Because the trial court only referred to the stocking in terms of evidence as opposed to fact, it is unclear whether the trial court made a finding that there was stocking of the Shepaug River at Roxbury.

We note, however, that the evidence reviewed by the court in this regard was undisputed at trial, and it is not challenged on appeal; only the legal consequences resulting from the alleged stocking are challenged. Moreover, on appeal, the defendants, the department and the attorney general all assume that the Shepaug River is a stocked river, but nevertheless argue, for reasons that we w

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