1. (a) Materials stimulating algal growth shall not be present in concentrations sufficient to cause objectionable algal densities or other nuisance aquatic vegetation or otherwise impair any designated use of the waterbody. Impairment of a waterbody from excess nutrients is dependent on the natural waterbody characteristics such as stream flow, residence time, stream slope, substrate type, canopy, riparian vegetation, primary use of waterbody, season of the year, and ecoregion water chemistry. Because nutrient water column concentrations do not always correlate directly with stream impairments, impairments will be assessed by a combination of factors such as water clarity, periphyton or phytoplankton production, dissolved oxygen values, dissolved oxygen saturation, diurnal dissolved oxygen fluctuations, pH values, aquatic-life community structure, and possibly others. However, when excess nutrients result in an impairment, based upon division assessment methodology or by any Arkansas established numeric water quality criteria, the waterbody will be determined to be impaired by nutrients.
2. (b) Site specific nutrient criteria. Lake Chlorophyll a (ug/L) Secchi Transparency (m) Beaver Lake¹⁵ 8¹⁶ 1.1¹⁷

3. (c)

   1. (1) All point source discharges into the watershed of waters officially listed on Arkansas's impaired waterbody list (Section 303(d) of the Clean Water Act, 33 U.S.C. § 1313(d)) with phosphorus as the major cause shall have monthly average discharge permit limits no greater than those listed below.
   2. (2) Additionally, waters in nutrient surplus watersheds as determined as set forth in Arkansas Code § 15-20-1104, and subsequently designated nutrient surplus watersheds may be included under this part if point source discharges are shown to provide a significant phosphorus contribution to waters within the listed nutrient surplus watersheds.
   3. (3) For discharges from point sources which are greater than fifteen million gallons per day (>15 mgd), reduction of phosphorus below one milligram per liter (1 mg/L) may be required based on the magnitude of the phosphorus load (mass) and the type of downstream waterbodies (e.g., reservoirs, Extraordinary Resource Waters). Additionally, any discharge limits listed above may be further reduced if it is determined that these values are causing impairments to special waters such as domestic water supplies, lakes or reservoirs, or Extraordinary Resource Waters.

Codification Notes: This section contains the following footnotes: Footnote 15 provides as follows: "These criteria are for measurement at the Hickory Creek site over the old thalweg, below the confluence of War Eagle Creek and the White River in Beaver Lake." Footnote 16 provides as follows: "Growing season geometric mean (May - October)." Footnote 17 provides as follows: "Annual Average."