Last Updated August 10, 2026 ARTICLE 44:02
CHAPTER 44:02:15
BIOLOGICAL FILTRATION POOLS
Section
44:02:15:01 Definitions.
44:02:15:02 Authority, purpose, and scope.
44:02:15:03 Permit application, fee, and reapplication restrictions.
44:02:15:04 Planning and siting.
44:02:15:05 Infrastructure requirements.
44:02:15:06 Structural and basin design.
44:02:15:07 Diving facilities.
44:02:15:08 Access structures.
44:02:15:09 Decks and shoreline areas.
44:02:15:10 Fencing and barriers.
44:02:15:11 Hydraulics and circulation.
44:02:15:12 Vegetation.
44:02:15:13 Safety, marking, and sign requirements.
44:02:15:14 Signs.
44:02:15:15 Water treatment and water‑quality standards.
44:02:15:16 Operation and maintenance.
44:02:15:17 Visitor load and capacity.
44:02:15:18 Water-quality monitoring.
44:02:15:19 Documentation and operations log.
Last Updated August 10, 2026 44:02:15:20 Safety, supervision, and public information.
44:02:15:21 Inspection, compliance, and enforcement.
Last Updated August 10, 2026 44:02:15:01. Definitions. Terms defined in SDCL 34-18-1 have the same meaning when
used in this chapter. Terms used in this chapter mean:
(1) “Biological filtration pool,” a water recreation facility in which water treatment is
accomplished through biological, physical, and mechanical processes within a regeneration zone
and in which chemical disinfectants are not used;
(2) “Guest,” an occupant of a rental unit of a lodging establishment;
(3) “Inspection,” an objective examination of a lodging establishment by the department
to review the employee practices, sanitary conditions, and health standards in accordance with
SDCL chapter 34-18 and this chapter;
(4) “Regeneration zone,” the portion of a biological filtration pool that contains aquatic
plants and granular or gravel media designed to biologically and physically filter water;
(5) “Turnover period,” the maximum time for the complete volume of the pool to pass
once through the circulation and filtration system;
(6) “Operator,” the individual designated by the licensee to perform daily operational,
safety, and maintenance duties of a biological filtration pool;
(7) “Swimming season,” the period from May 1 through September 30; and
(8) “Rinsing fixture,” a pool‑side rinse device located on the deck or entry path, used to
remove dirt, sand, sunscreen, or sweat before entering the pool. A rinsing fixture is not intended
for bathing, does not require soap, and may be a simple shower head or hose‑fed tap.
Source:
General Authority: SDCL 34-18-10.5, 34-18-22.
Law Implemented: SDCL 34-18-1, 34-18-10.5, 34-18-22, 34-18-24.
Last Updated August 10, 2026 44:02:15:02. Authority, purpose, and scope. This chapter establishes minimum
standards for the planning, siting, design, construction, operation, and maintenance of biological
filtration pools located at lodging establishments regulated under SDCL chapter 34‑18 that
utilize a biological filtration pool instead of chemically disinfected pool.
Source:
General Authority: SDCL 34-18-10.5, 34-18-22.
Law Implemented: SDCL 34-18-10.5, 34-18-22, 34-18-23, 34-18-24.
Last Updated August 10, 2026 44:02:15:03. Permit application, fee, and reapplication requirements. A lodging
establishment shall obtain a permit from the department before constructing or, if it already
exists, before operating a biological filtration pool. An application shall include:
(1) A completed permit application form provided by the department;
(2) Plans and specifications required under §§ 44:02:15:04 to 44:02:15:14, inclusive;
(3) Documentation demonstrating how the biological system will meet department-
established water‑quality outcomes;
(4) An operation and maintenance plan required under § 44:02:15:16; and
(5) Any additional information required by the department to evaluate public‑health
protection.
The nonrefundable permit fee is fifty dollars and shall be submitted with the application.
A permit is valid for one year and shall be renewed annually with the lodging
establishment license. Renewal requires:
(1) A completed renewal form;
(2) Updated water‑quality testing records; and
(3) Operational updates requested by the department.
If an establishment fails an inspection, the department shall revoke the permit. An
establishment that fails an inspection may not reapply for a permit for one year from the date of
the inspection.
Source:
General Authority: SDCL 34-18-10.5, 34-18-22.
Law Implemented: SDCL 34-18-10.5, 34-18-22, 34-18-23, 34-18-24.
Last Updated August 10, 2026 44:02:15:04. Planning and siting. The proposed site shall support stable ecological and
hydraulic performance. Planning considerations shall include:
(1) Groundwater level, soil structure, and suitability for sealing;
(2) Topography, sun exposure, shading, wind conditions;
(3) Availability of water supply, wastewater disposal, and utility access;
(4) Risk of flooding, noise sensitivity, or interference with surface water drainage; and
(5) Safe access for guests, emergency vehicles, and maintenance equipment.
Biological filtration pools may not be located where uncontrolled stormwater or surface water is
probable to enter the biological filtration pool based on grading, drainage patterns, slope, or
observed runoff behavior.
For purposes of this section, “stable ecological and hydraulic performance” means
aquatic vegetation remains healthy, filtration media remain permeable, water circulation is
evenly distributed, circulation systems maintain the required turnover rate, and overall conditions
do not impair water clarity, biological treatment processes, or public‑health protection.
Source:
General Authority: SDCL 34-18-10.5, 34-18-22.
Law Implemented: SDCL 34-18-10.5, 34-18-22, 34-18-23, 34-18-24.
Last Updated August 10, 2026 44:02:15:05. Infrastructure requirements. The lodging establishment shall provide
the following infrastructure in support of safe operation of the biological filtration pool:
(1) Separate, dedicated toilets and handwashing facilities shall be accessible from the
pool area;
(2) At least one shower or rinsing fixture shall be located near the pool entry to reduce
introduction of dirt, vegetation, and other contaminants;
(3) Pathways to the pool shall be designed to minimize the introduction of soil,
vegetation, or debris into the swimming or regeneration areas;
(4) Adequate waste containers shall be provided and protected from animals; and
(5) Life-saving equipment shall be provided in accordance with § 44:02:02:22.
Source:
General Authority: SDCL 34-18-10.5, 34-18-22.
Law Implemented: SDCL 34-18-10.5, 34-18-22, 34-18-23, 34-18-24.
Last Updated August 10, 2026 44:02:15:06. Structural and basin design. A biological filtration pool shall include a
designated swimming area physically separated from the regeneration zone. Depth indicators
shall be clearly visible at the perimeter. All surfaces include the deck, platforms, and steps shall
be slip-resistant and cleanable. Entry and exit shall be provided by ladders or stairs constructed
with non-skid materials. The regeneration zone substrate shall be granular or gravel not less than
six inches deep. The basin edges and sealing layers shall be protected from damage and prevent
uncontrolled inflow or outflow.
For purposes of this section, “sealing layers” means any impervious or near‑impervious
structural barrier used to prevent water loss or intrusion, including synthetic liners,
geomembranes, compacted clay layers, bentonite‑amended soils, concrete waterproofing
systems, or composite sealing materials installed as part of the pool basin design.
Source:
General Authority: SDCL 34-18-10.5, 34-18-22.
Law Implemented: SDCL 34-18-10.5, 34-18-22, 34-18-23, 34-18-24.
Last Updated August 10, 2026 44:02:15:07. Diving facilities. Only diving facilities with a platform or springboard
height of three feet or less may be installed. Diving facilities shall meet the following
requirements:
(1) A platform or springboard that is three feet high or less shall have a minimum water
depth of eleven feet directly beneath the diving plummet;
(2) Pool ladders located within a diving area shall be positioned at least twenty‑six feet
away from any pool side that contains a diving takeoff point;
(3) Indoor pools shall provide overhead clearance to prevent divers from contacting
structural elements above the platform or springboard;
(4) A lateral clearance of at least twenty‑six feet from the diving axis shall be maintained
to allow safe diver exit without crossing the path of incoming divers;
(5) Guard rails shall be installed on any platform three feet in height; and
(6) Access routes to diving platforms shall be designed to prevent unsafe or rapid entry
and shall be arranged to minimize collision risk.
Diving is prohibited outside the designated diving area.
Source:
General Authority: SDCL 34-18-10.5, 34-18-22.
Law Implemented: SDCL 34-18-10.5, 34-18-22, 34-18-23, 34-18-24.
Last Updated August 10, 2026 44:02:15:08. Access structures. Recessed steps, ladders, or stairs shall be provided at
the shallow end. Ladders or recessed steps shall be provided at the deep end. Pools wider than
thirty feet shall have steps, ladders, or stairs installed on each side. Steps, ladders, and stairs shall
not obstruct circulation patterns or biological filtration zones and shall allow safe movement
without creating slip or entrapment hazards.
Source:
General Authority: SDCL 34-18-10.5, 34-18-22.
Law Implemented: SDCL 34-18-10.5, 34-18-22, 34-18-23, 34-18-24.
Last Updated August 10, 2026 44:02:15:09. Decks and shoreline areas. Where a deck is installed, it shall be
constructed of slip‑resistant materials suitable for wet environments, be designed to prevent
runoff to the pool, and not interfere with biological filtration zones. Deck drainage shall not
connect directly to circulation or regeneration zones. Decks shall not obstruct visibility of the
water surface. Carpeting is prohibited on pool decks. Where concessions are provided,
concessions shall be located in a separate area from the pool deck and shall be designated for
serving and consuming food or drink.
Source:
General Authority: SDCL 34-18-10.5, 34-18-22.
Law Implemented: SDCL 34-18-10.5, 34-18-22, 34-18-23, 34-18-24.
Last Updated August 10, 2026 44:02:15:10. Fencing and barriers. The pool area shall be enclosed or controlled as
needed to prevent unauthorized access, considering the site's lodging use and safety risks.
Barriers or controlled access points may be required around technical equipment, regeneration
zones, or steep shore areas to prevent entry where hazards exist. Gates or access points shall
prevent unsupervised entry by children or untrained users when the facility is closed. Barriers
shall not obstruct water visibility or interfere with ecological or hydraulic performance.
Source:
General Authority: SDCL 34-18-10.5, 34-18-22.
Law Implemented: SDCL 34-18-10.5, 34-18-22, 34-18-23, 34-18-24.
Last Updated August 10, 2026 44:02:15:11. Hydraulics and circulation. The circulation system shall:
(1) Achieve a turnover period not exceeding twelve hours;
(2) Ensure even flow penetration throughout the swimming area to a depth sufficient to
prevent stagnation which is demonstrated when water movement reaches all areas and depths of
the swimming basin without creating stagnant zones, as verified through visual observation of
circulation patterns, proper functioning and placement of circulation inlets and outlets, and
consistent clarity throughout the swimming area;
(3) Use free-overfall discharge devices installed with consistent overflow height
tolerances;
(4) Arrange discharge equipment circumferentially for even distribution where the
distributing skimmers, overflow edges, or discharge channels are arranged around the perimeter
of the swimming area so that water is removed or directed uniformly from all sides, preventing
uneven circulation or stagnation; and
(5) Provide a retention basin behind discharge equipment for collection of debris.
Source:
General Authority: SDCL 34-18-10.5, 34-18-22.
Law Implemented: SDCL 34-18-10.5, 34-18-22, 34-18-23, 34-18-24.
Last Updated August 10, 2026 44:02:15:12. Vegetation. Regeneration zones shall use marsh plants or submerged
vegetation suitable for biological filtration. Marsh plants shall be installed between April and
September; submerged plants between spring and September. Vegetation shall be maintained to
prevent invasive growth, biomass accumulation, and impairment of filtration including plant
die‑off, clogged substrate, or any vegetative condition that reduces the biological filtering
performance of the regeneration zone.
For purposes of this section, “invasive growth” means vegetation spreading beyond the
intended regeneration zone or obstructing circulation.
For purposes of this section, “biomass accumulation” means excessive buildup of organic
material such as decaying plants or algae that interferes with water movement.
Source:
General Authority: SDCL 34-18-10.5, 34-18-22.
Law Implemented: SDCL 34-18-10.5, 34-18-22, 34-18-23, 34-18-24.
Last Updated August 10, 2026 44:02:15:13. Safety and marking requirements. Depth markings shall be in
accordance with § 44:02:02:22.
Source:
General Authority: SDCL 34-18-10.5, 34-18-22.
Law Implemented: SDCL 34-18-10.5, 34-18-22, 34-18-23, 34-18-24.
Last Updated August 10, 2026 44:02:15:14. Signs. Signs shall be in accordance with § 44:02:02:22.
Source:
General Authority: SDCL 34-18-10.5, 34-18-22.
Law Implemented: SDCL 34-18-10.5, 34-18-22, 34-18-23, 34-18-24.
Last Updated August 10, 2026 44:02:15:15. Water treatment and water‑quality standards. A biological filtration
pool may not use chemical disinfectants as part of routine operation or maintenance. The pool
shall be operated solely through biological, physical, and mechanical treatment processes
consistent with this chapter. The circulation system shall maintain a turnover of twelve hours or
less.
Water quality shall be maintained with a pH between 6.0 and 9.0. If pH exceeds 8.5, the
operator shall immediately conduct ammonia testing, as elevated pH increases ammonia toxicity
in natural water systems. Ammonia testing conducted due to elevated pH is required for
monitoring purposes only and does not establish an enforceable threshold.
Water quality shall be maintained with a total phosphorus < 0.01mg/l P. If total
phosphorus exceeds the threshold, the operator shall investigate and correct potential nutrient
sources, including runoff, substrate clogging, vegetation decay, or debris accumulation, and shall
perform follow‑up phosphorus testing at least weekly until results return to acceptable levels.
Elevated phosphorus that results in excessive algae growth or turbidity requiring closure under
this chapter shall be treated as an unsafe condition requiring immediate closure.
Water quality shall be maintained with a turbidity low enough to permit clear visibility of
the pool bottom at its greatest depth.
At least one water sample shall be submitted weekly to an EPA-certified laboratory for
the following microbial parameters:
Parameter Utilization area water
Escherichia coli CFU*/100ml < 100
Enterococci CFU*/100ml < 50
Pseudomonas aeruginosa CFU*/100ml < 10**
Last Updated August 10, 2026 * Colony-forming units
Escherichia coli and enterococci represent indicator organisms which are, as a rule, no
pathogens themselves, but may indicate the presence of pathogenic germs.
** Practice has shown that the sampling and identification of pseudomonas aeruginosa
requires special care.
The regeneration zone shall be maintained to ensure sufficient biological activity is
necessary for filtration. To remain compliant, the regeneration zone shall show: healthy aquatic
vegetation with no significant die‑off; a substrate free of clogging that maintains designed
hydraulic permeability; controlled biomass levels preventing flow obstruction; and verified even
flow penetration throughout the zone, as observed during inspections.
A positive E. coli result requires immediate closure of the pool. The operator shall notify
the department within twenty-four hours of receiving any unsafe water-quality result. The pool
shall remain closed until two consecutive water samples, collected at least twenty-four hours
apart, confirm E. coli levels are within allowable limits.
Conditions that pose a health hazard require immediate closure of the pool. These
conditions include:
(1) Positive E. coli test;
(2) Turbidity preventing the pool bottom from being clearly visible;
(3) Pump or circulation failure;
(4) Significant die-off of biological media or vegetation.
(5) Visible sewage or animal contamination;
(6) Excessive algae growth impairing clarity; or
(7) Any other condition the department determines poses an immediate health risk
Last Updated August 10, 2026 Water-quality testing procedures shall follow department-approved methods.
For purposes of this section, “significant die‑off” means any plant mortality that exceeds
ten percent of vegetation within a defined regeneration zone unit; or causes substrate clogging,
reduced permeability, decreased plant cover density, or diminished biological treatment function
verified through clarity checks, hydraulic observations, or debris accumulation.
Source:
General Authority: SDCL 34-18-10.5, 34-18-22.
Law Implemented: SDCL 34-18-10.5, 34-18-22, 34-18-23, 34-18-24.
Last Updated August 10, 2026 44:02:15:16. Operation and maintenance. The operator shall develop and implement a
written operation and maintenance plan that includes:
(1) Procedures for circulation, skimming, cleaning, and inspection;
(2) Maintenance of aquatic plants and substrate;
(3) A schedule for water‑quality testing; and
(4) Procedures for response to contamination or unsafe conditions.
Only mechanical or manual cleaning methods may be used. Chemical disinfectants,
algicides, or other water‑treatment chemicals may not be introduced into the pool or regeneration
zone.
Daily operational checks shall document water clarity, circulation, water level, and the
condition of the regeneration zone. Weekly water‑quality testing records shall be maintained
on‑site.
Records shall include the daily operational check logs, weekly water‑quality testing
results, documentation of all cleaning and maintenance activities, and all materials required
under the written operation and maintenance plan and shall be retained for at least three years
and made available to the department upon request.
Routine maintenance of the biological filtration system shall be performed as necessary
to preserve biological function, including removal of debris, care of aquatic vegetation, and
maintenance of circulation pathways.
For purposes of this section, “condition of the regeneration zone” means observable
vegetation health without die‑off; substrate that remains unclogged and permeable; absence of
excessive biomass or debris; and circulation patterns that show even flow penetration without
stagnation.
Last Updated August 10, 2026 Source:
General Authority: SDCL 34-18-10.5, 34-18-22.
Law Implemented: SDCL 34-18-10.5, 34-18-22, 34-18-23, 34-18-24.
Last Updated August 10, 2026 44:02:15:17. Visitor load and capacity. The operator shall calculate the maximum
nominal number of daily visitors using the following formula: N = 1/k (V_T + V_F + A•q),
where:
(1) N = nominal visitor number;
(2) K = person-related thinning factor (10 m³/person);
(3) V_T = regeneration‑capable water volume of utilization area (m³/d);
(4) V_F = daily filling water (m³/d);
(5) A = treatment‑area size (m²); and
(6) q = raw‑water inflow (m³/m²·day).
The nominal number represents the maximum designed daily visitor capacity of the biological
filtration pool and may not be routinely exceeded.
Temporary exceedance of the nominal number is only permitted when all water-quality
parameters in § 44:02:15:15 remain fully compliant and the exceedance does not impair
hydraulic performance, visible depth, vegetation condition, or biological filtration capacity. Any
exceedance shall be limited to no more than ten percent above the nominal number, consistent
with biological and hydraulic load tolerances established in recognized technical standards for
biological filtration systems. Exceedance above this threshold is prohibited. If any water‑quality
parameter required under § 44:02:15:15 becomes non‑compliant, visitor numbers shall
immediately be reduced to or below the nominal number until full compliance is restored.
The operator shall document daily visitor counts and make records available to the
department upon request.
Source:
General Authority: SDCL 34-18-10.5, 34-18-22.
Last Updated August 10, 2026 Law Implemented: SDCL 34-18-10.5, 34-18-22, 34-18-24.
Last Updated August 10, 2026 44:02:15:18. Water-quality monitoring. During the swimming season, in addition to
required weekly microbial testing, the operator shall perform daily temperature, pH, and
visibility measurements; twice-daily clarity checks; monthly total phosphorus and acid-capacity
testing; and nitrate and ammonia testing twice per season occurring once at the opening of the
pool and once at closing. Temperature, nitrate, and ammonia values are for monitoring purposes
only.
Outside the swimming season, operators shall conduct weekly clarity and circulation
checks and monthly pH and nutrient parameters, unless the pool is closed to guests. If a pool is
closed to guests outside of the swimming season, only monthly monitoring for clarity, pH, and
nutrient stability is required.
Sampling locations shall include the clean-water inlet and the utilization area at
approximately twelve inches in depth and twenty inches from basin edge.
Source:
General Authority: SDCL 34-18-10.5, 34-18-22.
Law Implemented: SDCL 34-18-10.5, 34-18-22, 34-18-24.
Last Updated August 10, 2026 44:02:15:19. Documentation and operations log. The operator shall maintain a daily
log documenting all water-quality data recorded under § 44:02:15:18, the total count of
individual persons who entered the utilization area during operating hours, weather conditions,
filling-water quantity, circulation volume, inspection and maintenance activities, and special
occurrences. Records shall be retained for three years.
For purposes of this section, “special occurrences” means any unusual, unexpected, or
abnormal event that affects water quality, circulation, vegetation condition, biological filtration
function, structural integrity, or public health protection.
Source:
General Authority: SDCL 34-18-10.5, 34-18-22.
Law Implemented: SDCL 34-18-10.5, 34-18-22, 34-18-24.
Last Updated August 10, 2026 44:02:15:20. Safety, supervision, and public information. The operator shall post
signage informing guests that biological filtration pools do not use chemical disinfectants and
may present natural-water health risks. Bathing rules shall be visibly posted. The operator shall
ensure supervision adequate for pool layout, capacity, and use.
Source:
General Authority: SDCL 34-18-10.5, 34-18-22.
Law Implemented: SDCL 34-18-10.5, 34-18-22, 34-18-24.
Last Updated August 10, 2026 44:02:15:21. Inspection, compliance, and enforcement. Biological filtration pools are
subject to inspection as provided in SDCL chapter 34‑18 and ARSD 44:02. An establishment
fails an inspection if during an inspection conducted under SDCL chapter 34-18, the department
identifies one or more critical violations or conditions that pose a risk to public health or safety,
or any violation of this chapter that requires immediate correction, closure, suspension, or other
enforcement action. An establishment fails an inspection if the inspector determines that the
facility is not in compliance with one or more requirements of this chapter, or any condition
defined in ARSD 44:02:15:15 as a health hazard requiring immediate closure.
The department may order corrective action, closure, suspension, or revocation of the
lodging establishment license, until compliance is achieved, or public‑health risks are eliminated.
The operator shall immediately close the pool if conditions pose a risk to public health.
Source:
General Authority: SDCL 34‑18‑10.5, 34-18-22.
Law Implemented: SDCL 34-18-10, 34‑18‑10.5, 34-18-21, 34-18-22, 34-18-24.