Missouri Code of State Regulations › Title 10 - DEPARTMENT OF NATURAL RESOURCES › Division 20 - Clean Water Commission › Chapter 7 - Water Quality › Section 10 CSR 20-7.031 - Water Quality Standards

Current through Register Vol. 49, No. 14, July 15, 2024
PURPOSE: The purpose of this amendment is to update
				  the Missouri Water Quality Standards in accordance with federal regulations at
				  40 CFR
				  131.20.
(1) Definitions.
(A) Acute toxicity-Conditions producing
				adverse effects or lethality on aquatic life following short-term exposure. The
				acute criteria in Tables A1, A2, and B1 are maximum concentrations which
				protect against acutely toxic conditions. Acute toxicity is also indicated by
				exceedence of whole-effluent toxicity (WET) test conditions of paragraph
				(4)(J)2. For substances not listed in Tables A1, A2, and B1, three-tenths (0.3)
				of the median lethal concentration, or the no observed acute effect
				concentration for representative species, may be used to determine absence of
				acute toxicity.
(B) Aquifer-A
				subsurface water-bearing bed or stratum which stores or transmits water in
				recoverable quantities that is currently being used or could be used as a water
				source for private or public use. It does not include water in the vadose
				zone.
(C) Biocriteria-Numeric
				values or narrative expressions that describe the reference biological
				integrity of aquatic communities inhabiting waters that have been designated
				for aquatic-life protection.
(D)
				Chronic toxicity-Conditions producing adverse effects on aquatic life or
				wildlife following long-term exposure but having no readily observable effect
				over a short time period. Chronic numeric criteria in Tables A1, A2, B2, and B3
				are maximum concentrations which protect against chronic toxicity; these values
				shall be considered four- (4-) day averages, with the exception of total
				ammonia as nitrogen which shall be considered a thirty- (30-) day average.
				Chronic toxicity is also indicated by exceedence of WET test conditions of
				subsection (5)(Q). For substances not listed in Tables A1, A2, B2, and B3,
				commonly used endpoints such as the no-observed effect concentration or
				inhibition concentration of representative species may be used to demonstrate
				absence of toxicity.
(E) Class-All
				waters in the Missouri Use Designation Dataset at (1)(Q) of this rule shall
				have a hydrologic class. During normal flow periods, some rivers back water
				into tributaries which do not otherwise have a hydrologic class. These
				permanent backwater areas are considered to have the same hydrologic class as
				the water body into which the tributary flows.
1. Class L1-Lakes used primarily for public
				drinking water supply.
2. Class
				L2-Major reservoirs.
3. Class
				L3-Other lakes which are waters of the state. These include both public and
				private lakes. For effluent regulation purposes, publicly-owned L3 lakes are
				those for which a substantial portion of the surrounding lands are publicly
				owned or managed.
4. Class
				P-Streams that maintain permanent flow even in drought periods.
5. Class P1-Standing-water reaches of Class P
				streams.
6. Class C-Streams that
				may cease flow in dry periods but maintain permanent pools which support
				aquatic life.
7. Class E-Streams
				that do not maintain permanent surface flow or permanent pools, but have
				ephemeral surface flow or pools in response to precipitation events.
8. Class W-Wetlands that are waters of the
				state that meet the criteria in the Corps of Engineers Wetlands Delineation
				Manual (January 1987), and subsequent federal revisions and supplements. Class
				W waters do not include wetlands that are artificially created on dry land and
				maintained for the treatment of mine drainage; stormwater control; or drainage
				associated with road construction, industrial, municipal, or agricultural
				waste.
(F) Designated
				uses-Uses specified for each water body whether or not they are being attained.
				Uses are designated according to section (2) of this rule and include, but are
				not limited to:
1. Protection and propagation
				of fish, shellfish, and wildlife. Streams will be designated to one (1) of the
				following aquatic habitat protection uses based on watershed size, scale within
				the stream network, and other hydrological and physical data. Lakes and
				reservoirs will be designated to one (1) of the following aquatic habitat
				protection uses based on limnological characteristics (such as temperature) and
				biological assemblages;
A. Warm Water Habitat
				(WWH)-Waters in which naturally-occurring water quality and habitat conditions
				allow the maintenance of a wide variety of warm-water biota-
(I) Great River;
(II) Large River;
(III) Small River;
(IV) Creek;
(V) Headwater; or
(VI) Lake or reservoir;
B. Cool Water Habitat (CLH)-Waters in which
				naturally-occurring water quality and habitat conditions allow the maintenance
				of a wide variety of cool-water biota. These waters can support a sensitive,
				high-quality sport fishery (i.e., smallmouth bass and rock bass)-
(I) Large River;
(II) Small River;
(III) Creek;
(IV) Headwater; or
(V) Lake or reservoir;
C. Cold Water Habitat (CDH)-Waters in which
				naturally-occurring water quality and habitat conditions allow the maintenance
				of a wide variety of cold-water biota. These waters can support a naturally
				reproducing or stocked trout fishery and populations of other cold-water
				species-
(I) Large River;
(II) Small River;
(III) Creek;
(IV) Headwater; or
(V) Lake or reservoir;
D. Ephemeral Aquatic Habitat (EAH)-Waters
				having surface flow or pools in response to precipitation events or snow melt,
				but without permanent surface flow or permanent pools; naturally-occurring
				water quality and habitat conditions may allow the maintenance of a limited or
				transient community of aquatic biota; and
E. Modified Aquatic Habitat (MAH)-Waters in
				which natural habitat conditions have been physically, chemically, or
				biologically modified; habitat and resulting water quality conditions may
				prevent the maintenance of a wide variety or diversity of aquatic
				biota.
F. Limited Aquatic Habitat
				(LAH)-Waters in which natural habitat conditions have been substantially and
				irretrievably altered; habitat and resulting water quality conditions do not
				allow maintenance of aquatic biota, or if present, the community is of poor
				variety or diversity;
2.
				Recreation in and on the water. Assignment of these uses does not grant an
				individual the right to trespass.
A. Whole
				body contact recreation (WBC)-Activities involving direct human contact with
				waters of the state to the point of complete body submergence. The water may be
				ingested accidentally and certain sensitive body organs, such as the eyes,
				ears, and the nose, will be exposed to the water. Although the water may be
				ingested accidentally, it is not intended to be used as a potable supply unless
				acceptable treatment is applied. Waters so designated are intended to be used
				for swimming, water skiing, or skin diving.
(I) Category A (WBC-A)-This category applies
				to waters that have been established by the property owner as public swimming
				areas welcoming access by the public for swimming purposes and waters with
				documented existing whole body contact recreational use(s) by the public.
				Examples of this category include, but are not limited to: public swimming
				beaches and property where whole body contact recreational activity is open to
				and accessible by the public through law or written permission of the
				landowner.
(II) Category B
				(WBC-B)-This category applies to waters designated for whole body contact
				recreation not contained within category A.
B. Secondary contact recreation (SCR)-Uses
				include fishing, wading, commercial and recreational boating, any limited
				contact incidental to shoreline activities, and activities in which users do
				not swim or float in the water. These recreational activities may result in
				contact with the water that is either incidental or accidental and the
				probability of ingesting appreciable quantities of water is minimal;
3. Human health protection
				(HHP)-Criteria to protect this use are based on the assumption of an average
				amount of fish consumed on a long-term basis. Protection of this use includes
				compliance with Food and Drug Administration (FDA) limits for fish tissue,
				maximum water concentrations corresponding to the
				10-6 cancer risk level, and other human health fish
				consumption criteria;
4. Irrigation
				(IRR)-Application of water to cropland or directly to cultivated plants that
				may be used for human or livestock consumption. Occasional supplemental
				irrigation, rather than continuous irrigation, is assumed;
5. Livestock and wildlife protection
				(LWP)-Maintenance of conditions in waters to support health in livestock and
				wildlife;
6. Drinking water supply
				(DWS)-Maintenance of a raw water supply which will yield potable water after
				treatment by public water treatment facilities;
7. Industrial water supply (IND)-Water to
				support various industrial uses; since quality needs will vary by industry, no
				specific criteria are set in these standards;
8. Storm- and flood-water storage and
				attenuation (WSA)- Wetlands and other waters which serve as overflow and
				storage areas during flood or storm events slowly release water to downstream
				areas, thus lowering flood peaks and associated damage to life and
				property;
9. Habitat for resident
				and migratory wildlife species, including rare and endangered species
				(WHP)-Wetlands and other waters that provide essential breeding, nesting,
				feeding, and predator escape habitats for wildlife including waterfowl, birds,
				mammals, fish, amphibians, and reptiles;
10. Recreational, cultural, educational,
				scientific, and natural aesthetic values and uses (WRC)-Wetlands and other
				waters that serve as recreational sites for fishing, hunting, and observing
				wildlife; waters of historic or archaeological significance; waters which
				provide great diversity for nature observation, educational opportunities, and
				scientific study; and
11.
				Hydrologic cycle maintenance (WHC)-Wetlands and other waters hydrologically
				connected to rivers and streams serve to maintain flow conditions during
				periods of drought. Waters that are connected hydrologically to the groundwater
				system recharge groundwater supplies and assume an important local or regional
				role in maintaining groundwater levels.
(G) Early life stages of fish-The pre-hatch
				embryonic period, the post-hatch free embryo or yolk-sac fry, and the larval
				period during which the organism feeds. Juvenile fish, which are anatomically
				rather similar to adults, are not considered an early life stage.
(H) Ecoregion-Ecoregions denote areas of
				general similarity in ecosystems and in the type, quality, and quantity of
				environmental resources. They are designed to serve as a spatial framework for
				the research, assessment, management, and monitoring of ecosystems and
				ecosystem components. By recognizing the spatial differences in the capacities
				and potentials of ecosystems, ecoregions stratify the environment by its
				probable response to disturbance (Bryce, Omernik, and Larsen, 1999).
(I) Epilimnion-Zone of atmospheric mixing in
				a thermostratified lake.
(J)
				Escherichia coli (E. coli)-A type of fecal coliform bacteria found in the
				intestines of animals and humans. The presence of E. coli in water is a strong
				indication of recent sewage or animal waste contamination. Sewage may contain
				many types of disease-causing organisms (pathogens).
(K) Eutrophication-The process by which a
				body of water becomes enriched in dissolved nutrients, such as nitrogen and
				phosphorus, that stimulate the excessive growth of algae and other plants.
				Eutrophication may be accelerated by human activities.
(L) Existing uses-Those uses actually
				attained in the water body on or after November 28, 1975, whether or not they
				are identified in the water quality standards.
(M) Hypolimnion-Zone beneath the zone of atmospheric
				mixing in a thermostratified lake.
(N) Lethal concentration50
				(LC50)-Concentration of a toxicant which would be
				expected to kill fifty percent (50%) of the individuals of the test species
				organisms in a test of specified length of time.
(O) Losing stream-A stream which distributes thirty
				percent (30%) or more of its flow during low flow conditions through natural
				processes, such as through permeable geologic materials into a bedrock aquifer
				within two (2) miles' flow distance downstream of an existing or proposed
				discharge. Flow measurements to determine percentage of water loss must be
				corrected to approximate the 7Q10 stream flow. If a stream bed or drainage way
				has an intermittent flow or a flow insufficient to measure in accordance with
				this rule, it may be determined to be a losing stream on the basis of channel
				development, valley configuration, vegetation development, dye tracing studies,
				bedrock characteristics, geographical data, and other geological factors.
				Losing streams are identified in the digital geospatial dataset 'LOSING_STREAM'
				developed by the Missouri Department of Natural Resources, Missouri Geological
				Survey; additional streams may be determined to be losing by the Missouri
				Department of Natural Resources.
(P) Low-flow conditions-Where used in this regulation
				in the context of mixing zones, the low-flow conditions shall refer to the
				minimum amount of stream flow occurring immediately upstream of a wastewater
				discharge and available, in whole or in part, for attenuation of wastewater
				pollutants.
1. Seven- (7-) day, one- (1-)
				in-ten- (10-) year low flow (7Q10)-The lowest average flow for seven (7)
				consecutive days that has a probable recurrence interval of once-in-ten (10)
				years.
2. Sixty- (60-) day, one-
				(1-) in-two- (2-) year low flow (60Q2)-The lowest average flow for sixty (60)
				consecutive days that has a probable recurrence interval of once-in-two (2)
				years.
3. Thirty- (30-) day, one-
				(1-) in-ten- (10-) year low flow (30Q10)-The lowest average flow for thirty
				(30) consecutive days that has a probable recurrence interval of once-in-ten
				(10) years.
4. One- (1-) day, one-
				(1-) in-ten- (10-) year low flow (1Q10)- The lowest average flow for one (1)
				day that has a probable recurrence interval of once-in-ten (10)
				years.
(Q) Missouri Use
				Designation Dataset-A digital geospatial dataset maintained by the department
				and used in conjunction with geographic information systems. This dataset
				documents the class and locations of designated uses assigned the state's
				rivers, streams, lakes, and reservoirs. The initial version of this dataset,
				8-20-13 MUDD V1.0, was adopted on November 6, 2013, to reflect Tables G and H
				plus any additional presumptive uses described in section (2). The dataset will
				also include information regarding both pending and approved determinations,
				variances, use attainability analyses, and water quality standards revisions.
				The dataset uses the geospatial framework provided by the National Hydrography
				Dataset and is enhanced and supported by hydrological and physical information
				obtained through the Missouri Resource Assessment Partnership and other
				scientific sources. The dataset is limited in geographic extent to the state of
				Missouri. Current versions of the Missouri Use Designation Dataset are titled
				'STRM_CLS_USE' and 'LAKE_CLS_USE' dated December 30, 2020.
(R) Mixing zone-An area of dilution of effluent in the
				receiving water beyond which chronic toxicity criteria must be met.
(S) National Hydrography Dataset (NHD)-A
				digital vector dataset used in conjunction with geographic information systems
				to describe the location of rivers, streams, lakes, reservoirs, and other
				surface water features. This dataset provides the geospatial framework for the
				Missouri Use Designation Dataset.
(T) Outstanding national resource waters-Waters which
				have outstanding national recreational and ecological significance. These
				waters shall receive special protection against any degradation in quality.
				Congressionally-designated rivers, including those in the Ozark national scenic
				riverways and the wild and scenic rivers system, are so designated (see Table
				D).
(U) Outstanding state resource
				waters-High quality waters with a significant aesthetic, recreational, or
				scientific value which are specifically designated as such by the Clean Water
				Commission (see Table E).
(V)
				Ozark streams-Streams lying within the Ozark faunal region as described in the
				Aquatic Community Classification System for Missouri, 1989, Aquatic Series No.
				19, Missouri Department of Conservation, Jefferson City, MO 65109, which is
				hereby incorporated by reference and does not include any later amendments or
				additions. The department shall maintain a copy of the referenced documents and
				shall make them available to the public for inspection and copying at no more
				than the actual cost of reproduction.
(W) Reference lakes or reservoirs-Lakes or reservoirs
				determined by Missouri Department of Natural Resources to be the best available
				representatives of ecoregion waters in a natural condition with respect to
				habitat, water quality, biological integrity and diversity, watershed land use,
				and riparian conditions.
(X)
				Reference stream reaches-Stream reaches determined by the department to be the
				best available representatives of ecoregion waters in a natural condition, with
				respect to habitat, water quality, biological integrity and diversity,
				watershed land use, and riparian conditions.
(Y) Regulated-flow streams-A stream that derives a
				majority of its flow from an impounded area with a flow-regulating
				device.
(Z) Use Attainability
				Analysis (UAA)-A structured scientific assessment of the factors affecting the
				attainment of the use which may include physical, chemical, biological, and
				economic factors as described in
				40 CFR
				131.10(g).
(AA) Variance-A temporary modification to 10
				CSR 20-7.031 that is deemed necessary in accordance with section (12) of this
				rule.
(BB) Water effect
				ratio-Appropriate measure of the toxicity of a material obtained in a site
				water divided by the same measure of the toxicity of the same material obtained
				simultaneously in a laboratory dilution water.
(CC) Water hardness-The total concentration of calcium
				and magnesium ions expressed as calcium carbonate. For purposes of this rule,
				hardness will be the median value of a representative number of samples from
				the water in question or from similar waters at the appropriate stream flow
				conditions within the same ecoregion.
(DD) Water quality criteria-Chemical,
				physical, and biological properties of water that are necessary to protect
				designated uses.
(EE) Waters of
				the state- As defined in section
				644.016, RSMo.
(FF) Wetlands-Those areas that
				are inundated or saturated by surface or groundwater at a frequency and
				duration sufficient to support, and that under normal circumstances do support,
				a prevalence of vegetation typically adapted for life in saturated soil
				conditions. Wetlands generally include swamps, marshes, bogs, and similar
				areas. This definition is consistent with both the United States Army Corps of
				Engineers wetlands definition at
				33
				CFR 328.3(b) and the United
				States Environmental Protection Agency wetlands definition at
				40
				CFR 232.2(r).
(GG) Whole effluent toxicity tests-A
				toxicity test conducted under specified laboratory conditions on specific
				indicator organisms. To estimate chronic and acute toxicity of the effluent in
				its receiving stream, the effluent may be diluted to simulate the computed
				percent effluent at the edge of the mixing zone or zone of initial
				dilution.
(HH) Zone of initial
				dilution-A small area of initial mixing below an effluent outfall beyond which
				acute toxicity criteria must be met.
(II) Zone of passage-A continuous water route
				necessary to allow passage of organisms with no acutely toxic effects produced
				on their populations.
(JJ) Other
				definitions as set forth in the Missouri Clean Water Law and
				10 CSR 20-2.010 shall
				apply to terms used in this rule.