RCW 90.54.020 requires that perennial rivers and streams shall be retained with base flows necessary to provide for preservation of wildlife, fish, scenic, aesthetic, and other environmental values and navigational values. Under this provision, base flows for stream management units of a basin are established which describe discharge rates at stream measurement stations in each unit. The following subsections, WAC 173-559-030 (1) through (4), establish these requirements for WRIA 59:

1. (1) In the Colville River basin, monitoring of base flows will take place at the following control points:

   Table 1

   Stream Management Units

   Stream ManagementUnit and ControlStation Number	Control Station Locationby River-Mile, and Section Township and Range	StreamManagementReach
   Upper Colville RiverNo. 12.4080.00		32.1Sec. 31, T. 33 N., R. 40 E.W.M.	Colville Riverfrom confluence with Stensgar Creek to confluence of Sheep Creek and Deer Creek.
   Lower Colville RiverNo. 12.4090.00		5.0Sec. 29, T. 36 N., R. 38 E.W.M.	Colville River from confluence with Lake Roosevelt to confluence with Stensgar Creek.

2. (2) In the Colville River basin, base flows for the stream management units in WAC 173-559-030(1) are set in Table 2 as follows:

   Table 2

   Base Flows in the Colville River basin

   (in Cubic Feet Per Second)

   Month	Day	UpperColville(12.4080.00)	LowerColville(12.4090.00)
   Jan.	1	30	80
   	15	30	80
   Feb.	1	30	80
   	15	38	100
   Mar.	1	47	124
   	15	59	157
   Apr.	1	76	200
   	15	76	200
   May	1	49	200
   	15	32	135
   Jun.	1	20	90
   	15	17	70
   Jul.	1	15	55
   	15	13	43
   Aug.	1	11	33
   	15	11	33
   Sep.	1	14	40
   	15	18	49
   Oct.	1	22	60
   	15	27	70
   Nov.	1	35	84
   	15	43	100
   Dec.	1	43	100
   	15	36	90

3. (3) Figure 1, base flow hydrographs for selected stations, shall be used to define base flows on those days not identified in WAC 173-559-030(2).

4. (4) All surface water rights, established by appropriation in the Upper Colville and Lower Colville stream management units after adoption of this regulation, shall be subject to the base flows set in WAC 173-559-030 (1) through (3). However, these base flows will not apply to in-house domestic use and stock watering use, if an alternate source is not available to satisfy these uses. If the cumulative impact of numerous single in-house domestic use diversions is determined to substantially affect a stream's base flow or existing rights, then new permits for this use may be denied.

   Figure 1

   base flow hydrograph for selected stations

   [if IE 9]><video style="display: none;"><![endif][if IE 9]></video><![endif]

[Order DE 77-6, § 173-559-030, filed 7/22/77.]